Fundamental Philosophy Surgery Series

Fundamental Philosophy Surgery Series | Head and Neck

Fundamental Philosophy Anatomy Dictionary: Head and Neck

Preface

To start, this text has been one which has served well in the way of being a milestone for the overarching project at hand that can be rightly titled as the Fundamental Philosophy Library, and accomplishing its completion has done much to warm my spirit regarding this endeavor. I would like to say that the motivations behind undertaking this adventure have been the true source of inspiration for this work and others, but that would be an understatement considering the joy I feel with the completion of each work, text, piece, or volume. The rudimentary nuances of the whole of the body of literature, at this point, has also rang many notions with my person, and I feel as though, given time, the future will hold an inviting array of improvements to be made. In the light of that revelation, though, I would like to spell many ‘pats on the back’ for the project as it currently stands, as it is gearing well toward completion and consistently tackling each step with determination, effort, perseverance, and tenacity will assuredly see to the larger objective being achieved. That project, again, being the completion of a working library model built on education, medicine, and law to the degree of philosophy’s fundamental observance. The pathway for which being one that resides along the road of books, art, and principled study. However, with the intents and purposes of the Fundamental Philosophy series being built upon the aforewritten triumvirate of education, medicine, and law, there exists also the capacity to expound upon and develop the principles of the library’s works through the cultivation of my own personal narrative. It is one that sees to the principled study of family, community, and togetherness through the lens of personal reflection and relentless contribution wherein there is seeded a powerful sentiment of victory which is attained through work and honest effort. It is by that notion, in honest mention, that this work finds a resonant place at the beginning of a journey to be defined by principle, and the song which is made from that air of decisive exploration is one that echoes volumes for what can be taught along its telling. From these rooted givings, then, I call upon this project to be one that expresses an adept encouragement for those who are seeking to not only begin but also advance their own studies through journey thereupon finding a treasure that is to be heralded above all others in the way of family and friendship. Community is what builds further that dynamic, and the complexity of that relationship is no more profound than the effort one contributes to surmounting the goal of salutation. It is a careful word toward one’s betterment, and I would like to say that it is one that assuredly gifts one a warm contentment of good, the same.

Knowing the above, then, to be a word toward one’s own enrichment and fostered prosperity, the work set below is one that can be rightly viewed as a fundamental construction to be positioned within a larger, more inclusive scope of gradated thought. One that will gift the keys necessary to unlocking the secrets to a richer and more fulfilling life. Without the fundamental building blocks of education, medicine, and law articulated in alphabetic succession below, there would be no world known by its modernity or contemporary measure. There would be only darkness, and it is from that spark of radiant revelation that the below seeds light and life in one’s journey.

Introduction

Shoutout to ChatGPT as well as Frank H. Netter and his team! Without their work, this text series would not be possible.

There is a serial purpose and fitting principle to this text. It is one that is based squarely in the cyclicality of the university’s educational curriculum, and it is also one that is compounded further by the general mission of this body of literature titled under the Fundamental Philosophy banner. That purpose is to integrate the practices, disciplines, and understandings of humanity into a surgical context, so as to see to an enriched clarity regarding the relevant knowledges associated with their relevant doctoral wisdom and surgical principle. The founding basis for this objective is rooted in the general objective and purpose ascribed to any curriculum, and that is one which sees to the holistic connection of its working doctrine as being possible from the introduction of its cycled machinations. The mechanics surrounding the Fundamental Philosophy curriculum are built upon the aforescribed notion along the inclusive axes of medicine and education. From the duality of that poignant connection, there exists naturally the principled fielding of law whereupon there is found furthered the surgical purpose of humanity’s doctoral mission. This text is charged with that mission, and it accomplishes that goal by serving as a reference piece to the larger Fundamental Philosophy collection. Prior to the beginning of the text, then, as a conclusive point of example and reference, consider the overarching curriculum to be inherently understood as a natural part and holistic medium for this work and its associated volumes. Fledgling philosophical understanding of the medical terms found in this work can be had with the associated preparatory text of this series as well as the conclusive encyclopedia series which accompanies the medical philosophy of the Fundamental Philosophy library and curriculum. Starting with the Fundamental Philosophy Preparatory Text, then, and moving onward to the Fundamental Philosophy Encyclopedia series, the precepts for medical philosophy which can be found in the two prior examples are ones which naturally lead one’s person to the need for greater clarity along the axes of serial interpretation. This work and the larger series of which it is a part is to serve as the answer for that clarity. Through the use of its definitions and termings, there is a means by which to understand the anatomy of the human body via lens of whole inspection. That principled arrangement is what, then, places human identity and subsequently humanity into greater context because of the ability to make sense of the human body at a level which is not only conclusive but also inclusive considering the connection one’s person maintains with humanity as a whole. Knowing the human body at a surgical level serves the resonant purpose of making sense of existence due to the inevitability to see one’s self as a part of creation through serial instrumentations and devices. Anatomy is the gateway to a larger and more worldly understanding, and the propensity to seed its blossoming knowledges within the prose of a curriculum’s narrative is one that invites inclusion along the dimensions of humanity’s all encompassing narrative. Allow, then, this work to be one that spells greatly for the others of surgical and doctoral design which are to follow.

Abducent nerve

The abducent nerve is the 6th cranial nerve (CN VI). It is a purely motor nerve whose main job is to move the eye laterally.

Abducent nucleus

The abducent nucleus is the motor nucleus of the abducent nerve (cranial nerve VI).

Accessory meningeal artery

The accessory meningeal artery is a small branch of the maxillary artery that mainly supplies the dura mater and nearby structures at the skull base.

Accessory muscle bundle

The accessory muscle bundle refers to an anomalous or extra slip of skeletal muscle fibers that occurs in addition to the normal, expected muscles of a region. These are considered anatomical variants.

Accessory nasal cartilage

The accessory nasal cartilages are small paired cartilages of the external nose that serve as transitional elements between the major nasal cartilages.

Accessory nerve

The accessory nerve is the 11th cranial nerve (CN XI). It is a motor nerve with two roots: a cranial part and a spinal part.

Accessory oculomotor (Edinger-Westphal) nucleus

The accessory oculomotor nucleus, more commonly called the Edinger–Westphal nucleus, is the parasympathetic nucleus of the oculomotor nerve (cranial nerve III).

Accessory parotid gland

The accessory parotid gland is a small, separate lobe of salivary tissue associated with the main parotid gland. It is a normal anatomical variant found in many people.

Accessory vertebral vein

The accessory vertebral vein is a variable tributary of the vertebral venous system that provides an additional pathway for venous drainage of the neck.

Acromion

The acromion is a bony projection on the scapula (shoulder blade) that forms the highest point of the shoulder.

Adenohypophysis

The adenohypophysis is the anterior lobe of the pituitary gland — the part responsible for producing and secreting hormones that regulate many endocrine glands and body functions.

Afferent fiber

An afferent fiber is a nerve fiber that carries sensory information toward the central nervous system (CNS) — that is, from receptors to the brain or spinal cord.

Agger nasi

The agger nasi is a small ridge or elevation on the lateral wall of the nasal cavity, located anterior and superior to the middle nasal concha. It is an important surgical and anatomical landmark in the nasal cavity and paranasal sinus region.

Airway to nasopharynx

The airway to the nasopharynx refers to the uppermost part of the respiratory passage — the portion of the pharynx that lies behind the nasal cavity and above the soft palate. It serves as the pathway for inspired and expired air traveling between the nasal cavity and the oropharynx/larynx.

Ala of nose

The ala of the nose (plural: alae) refers to the flaring, curved outer part of the nostril — the lateral wall that forms the rounded contour of the nose’s base.

Alar branches of lateral nasal branch (of facial artery)

The alar branches of the lateral nasal branch of the facial artery are small arterial branches that supply the ala (wing) of the nose — particularly the lateral and inferior parts of the nostril.

Alar fascia

The alar fascia is a thin layer of deep cervical fascia located in the neck, forming part of the deep cervical fascial system. It plays an important role in separating and defining the deep spaces of the neck — especially in the spread of infections.

Alar fibrofatty tissue

The alar fibrofatty tissue is a specialized soft tissue component of the external nose, located within the ala of the nose (the lateral “wing” of each nostril). It plays a key role in nasal shape, mobility, and airway patency.

Alar ligament

The alar ligaments are strong, paired ligaments of the craniovertebral junction that play a critical role in stabilizing the skull on the cervical spine, particularly by limiting excessive rotation.

Alar part of nasalis muscle

The alar part of the nasalis muscle is a small muscle of facial expression located on the side of the nose, primarily responsible for widening (flaring) the nostrils.

Alveolar process of maxilla

The alveolar process of the maxilla is the bony ridge of the maxilla that contains the sockets (alveoli) for the upper teeth. It plays a critical role in supporting the teeth and forming the dental arch.

Alveolar foramina

The alveolar foramina are small openings in the alveolar processes of the jawbones (maxilla and mandible) that allow passage of nerves and blood vessels supplying the teeth and surrounding tissues.

Alveolar part (crest)

The alveolar part (alveolar crest) of the jawbone refers to the ridge of bone that contains the tooth sockets (alveoli) in the maxilla and mandible. It is the most superior portion of the alveolar process and plays a key role in supporting the teeth.

Alveolar periosteum

The alveolar periosteum is the fibrous connective tissue layer that covers the alveolar process of the jawbones (maxilla and mandible), playing a key role in tooth support, bone remodeling, and periodontal health.

Alveolar process

The alveolar process is the bony ridge of the maxilla or mandible that contains the tooth sockets (alveoli), providing support and stability for the teeth. It is a key part of the dental arch and periodontium.

Alveolar recesses of maxillary sinus

The alveolar recesses of the maxillary sinus are inferior extensions of the maxillary sinus that project into the alveolar process of the maxilla, lying above the roots of the upper teeth.

Alveus of hippocampus

The alveus of the hippocampus is a thin layer of white matter on the ventricular surface of the hippocampus that contains axons projecting from the hippocampal pyramidal neurons to other brain regions, forming the initial part of the fornix pathway.

Amacrine cells

Amacrine cells are interneurons in the retina that play a crucial role in modulating visual signals between bipolar cells and ganglion cells, particularly in temporal and spatial processing of visual information.

Ampulla of lateral semicircular duct

The ampulla of the lateral semicircular duct is an expanded region at the base of the lateral (horizontal) semicircular canal in the inner ear, which contains the crista ampullaris, the sensory organ responsible for detecting rotational movements (angular acceleration) of the head.

Ampulla of posterior semicircular duct

The ampulla of the posterior semicircular duct is an enlarged portion at the base of the posterior semicircular canal in the inner ear that contains the crista ampullaris, the sensory organ responsible for detecting angular acceleration (rotational movements) in the vertical plane.

Ampulla of superior semicircular duct

The ampulla of the superior semicircular duct (also called the anterior semicircular canal) is an expanded portion at the base of the superior semicircular canal in the inner ear, containing the crista ampullaris, which is the sensory structure responsible for detecting angular acceleration in the vertical plane.

Ampullae

The term “ampullae” (plural of ampulla) generally refers to expanded or dilated regions of tubular structures in the body. In anatomy, ampullae are important as sensory, transport, or storage structures, depending on the system.

Amygdaloid bodies

The amygdaloid bodies, commonly called the amygdala, are paired almond-shaped clusters of nuclei located in the temporal lobes of the brain, forming a key part of the limbic system. They are deeply involved in emotional processing, memory, and behavior.

Anastomose

The term “anastomose” (verb) refers to the connection or joining of two tubular structures such as blood vessels, lymphatic vessels, or nerves, allowing communication or alternative pathways for flow.

Angle of jaw (mandible)

The angle of the jaw (also called the angle of the mandible or gonial angle) is the posteroinferior corner of the mandible where the body of the mandible meets the ramus. It is an important landmark for muscle attachment, facial contour, and clinical procedures.

Angular artery

The angular artery is the terminal branch of the facial artery, supplying the side of the nose and the medial (inner) angle of the eye. It plays an important role in facial blood supply and in anastomoses between branches of the external and internal carotid arteries.

Angular gyrus of inferior parietal lobule

The angular gyrus is a convoluted cortical region located in the posterior part of the inferior parietal lobule of the brain. It plays a key role in language, reading, writing, number processing, and spatial cognition, and serves as an important association area connecting visual, auditory, and somatosensory information.

Angular vein

The angular vein is a facial vein located near the medial angle (inner corner) of the eye. It is formed by the union of veins from the forehead and nose, and it serves as an important connection between superficial facial veins and the deep venous system, including intracranial veins.

Anomalous (retroesophageal) right subclavian artery

The anomalous (retroesophageal) right subclavian artery — also known as arteria lusoria — is a common vascular anomaly where the right subclavian artery arises abnormally from the aortic arch, distal to the left subclavian artery, and passes behind the esophagus (retroesophageal) to reach the right upper limb.

Anomalous right inferior laryngeal nerve

The anomalous right inferior laryngeal nerve (also known as the non-recurrent laryngeal nerve) is a rare anatomical variation of the recurrent laryngeal nerve—a branch of the vagus nerve (cranial nerve X)—in which the nerve does not loop around the subclavian artery as it normally does.

Ansa cervicalis

The ansa cervicalis is a loop of nerves in the neck that is part of the cervical plexus. It provides motor innervation to most of the infrahyoid muscles, which are involved in swallowing and movements of the larynx.

Ansa of galen

The Ansa of Galen (also called Ansa lenticularis) is a loop-shaped fiber tract in the brain that is part of the basal ganglia circuitry, involved in motor control.

Ansa subclavia

The ansa subclavia is a nerve loop found in the lower neck, associated with the sympathetic nervous system, not the somatic motor system like the ansa cervicalis.

Ansacervicalis (C1, C2, C3)

The ansa cervicalis is a nerve loop in the neck that provides motor innervation to most of the infrahyoid muscles (the "strap muscles")—important for swallowing and speaking.

The term "anterior" is an anatomical directional term used to describe the front or forward-facing side of the body or a body part.

Anterior and posterior branches of inferior laryngeal nerve

The inferior laryngeal nerve is the terminal branch of the recurrent laryngeal nerve, which itself is a branch of the vagus nerve (CN X). After entering the larynx, it divides into anterior and posterior branches that innervate the intrinsic muscles of the larynx (except one).

Anterior and posterior cochlear nuclei

The anterior and posterior cochlear nuclei are the first central relay stations in the auditory pathway. They are located in the brainstem, specifically at the junction of the pons and medulla, and they receive input directly from the cochlear (auditory) nerve, which is part of the vestibulocochlear nerve (cranial nerve VIII).

Anterior and posterior intercavernous sinuses

The anterior and posterior intercavernous sinuses are venous channels located at the base of the brain. They are part of the cerebral venous sinus system and specifically help interconnect the right and left cavernous sinuses across the midline, around the pituitary gland.

Anterior and posterior meningeal branches of vertebral artery

The vertebral artery gives off anterior and posterior meningeal branches that supply the meninges (protective coverings of the brain and spinal cord), particularly in the posterior cranial fossa.

Anterior antlantoocipital membrane

The anterior atlanto-occipital membrane is a ligamentous membrane that connects the base of the skull to the first cervical vertebra (atlas) on the anterior (front) side of the neck. It plays an important role in stabilizing the craniovertebral junction and limiting excessive movement.

Anterior arch

The anterior arch refers primarily to the anterior arch of the atlas (C1 vertebra), which is a crucial bony structure in the upper cervical spine.

Anterior articular facet (for anterior arch of atlas)

The anterior articular facet is a specific smooth surface located on the dens (odontoid process) of the axis (C2 vertebra).

Anterior atlantooccipital membrane

The anterior atlanto-occipital membrane is a thin, fibrous ligament that connects the front (anterior) part of the base of the skull (specifically, the anterior margin of the foramen magnum) to the front of the first cervical vertebra, called the atlas (C1). It lies over the atlanto-occipital joint, which is the joint where the skull meets the spine.

Anterior auricular arteries

The anterior auricular arteries are small branches of the superficial temporal artery, which itself is a terminal branch of the external carotid artery.

Anterior auricular nerves of mandibular nerve

The anterior auricular nerves of the mandibular nerve (CN V₃) are sensory nerve branches that supply the anterior part of the external ear (auricle) and adjacent regions. These nerves are branches of the auriculotemporal nerve, which is itself a branch of the mandibular division of the trigeminal nerve.

Anterior belly

An anterior belly generally refers to the front part of a muscle that has two parts (bellies)—an anterior (front) and a posterior (back) belly.

Anterior cerebellar notch

The anterior cerebellar notch is a specific anatomical feature on the clivus, a part of the basilar part of the occipital bone at the base of the skull.

Anterior cerebral arteries

The anterior cerebral arteries (ACAs) are paired arteries that supply blood to the medial portions of the frontal lobes and superior medial parietal lobes of the brain.

Anterior cerebral vein

The anterior cerebral veins are veins that drain blood from the medial surfaces of the frontal lobes of the brain.

Anterior chamber of eye

The anterior chamber of the eye is a key anatomical space involved in maintaining eye pressure and health.

Anterior choroidal artery

The anterior choroidal artery is a small but important artery that arises from the internal carotid artery inside the brain.

Anterior ciliary artery

The anterior ciliary artery is a small artery that supplies blood to the front (anterior) part of the eye and its surrounding tissues.

Anterior ciliary vein

The anterior ciliary veins are veins that drain blood from the front (anterior) part of the eye and its surrounding structures.

Anterior clinoid process

The anterior clinoid process is a small, bony projection located at the base of the skull, near the center of the cranial cavity.

Anterior cochlear nuclei

The anterior cochlear nucleus is one of the two main divisions of the cochlear nucleus, which is the first central relay station in the auditory pathway where signals from the ear are processed in the brainstem.

Anterior commissure

The anterior commissure is a bundle of nerve fibers (white matter) in the brain that connects the two cerebral hemispheres, specifically linking parts of the temporal lobes, including the olfactory (smell) areas.

Anterior communicating artery

The anterior communicating artery (AComA) is a short but critically important artery in the brain that connects the left and right anterior cerebral arteries. It is a central part of the Circle of Willis, a ring-like arterial system that helps ensure consistent blood flow to the brain.

Anterior cranial fossa

The anterior cranial fossa is the front part of the floor of the skull that supports the frontal lobes of the brain.

Anterior deep cervical nodes

The anterior deep cervical lymph nodes are a group of lymph nodes located deep in the neck, along the anterior (front) aspect of the internal jugular vein, beneath the sternocleidomastoid muscle.

Anterior deep temporal arteries and nerves

The anterior deep temporal arteries and nerves are structures that supply and innervate the temporalis muscle, a key muscle involved in chewing (mastication).

Anterior division

The term "anterior division" is often used in anatomy to describe a branch of a nerve or blood vessel that splits toward the front (anterior) part of the body. It appears in multiple contexts depending on the system or region being discussed.

Anterior ethmoidal artery

The anterior ethmoidal artery is a small but important artery in the head, particularly in the orbit and nasal cavity.

Anterior ethmoidal cells

The anterior ethmoidal cells are part of the ethmoid sinus system, which itself is a component of the paranasal sinuses. These small air-filled cavities are located between the nose and the eyes and play a role in respiratory function, mucus drainage, and lightening the weight of the skull.

Anterior ethmoidal foramen

The anterior ethmoidal foramen is a small opening in the skull that serves as a passage for neurovascular structures between the orbit, cranial cavity, and nasal cavity.

Anterior ethmoidal nerve

The anterior ethmoidal nerve is a sensory nerve in the face and nasal region. It is a branch of the nasociliary nerve, which comes from the ophthalmic division (V1) of the trigeminal nerve (cranial nerve V).

Anterior ethmoidal vein of anterior ethmoidal foramen

The anterior ethmoidal vein is a small but important venous structure that accompanies the anterior ethmoidal artery and nerve through the anterior ethmoidal foramen. It plays a role in venous drainage of the orbit, anterior cranial fossa, and nasal cavity.

Anterior external vertebral venous plexus

The anterior external vertebral venous plexus is part of the vertebral venous system, a complex network of interconnected valveless veins surrounding and within the vertebral column. This specific plexus is located anterior (in front of) the vertebral bodies, outside the spinal canal.

Anterior fontanelle

The anterior fontanelle is the largest and most clinically important fontanelle in a newborn's skull. It’s a soft spot where several cranial bones haven't yet fused, allowing for brain growth and skull flexibility during birth.

Anterior inferior cerebellar artery

The anterior inferior cerebellar artery (AICA) is one of the three main arteries that supply the cerebellum, alongside the superior cerebellar artery (SCA) and the posterior inferior cerebellar artery (PICA).

Anterior intercostal arteries

The anterior intercostal arteries are branches of arteries in the thoracic wall that supply blood to the intercostal spaces (the spaces between the ribs). They are part of the thoracic wall’s vascular supply, complementing the posterior intercostal arteries.

Anterior internal (epidural) vertebral venous plexus

The anterior internal (epidural) vertebral venous plexus is a key component of the vertebral venous system, which is a complex network of valveless veins located within and around the vertebral column. This plexus plays an important role in venous drainage of the spine and surrounding structures.

Anterior jugular vein

The anterior jugular vein is a superficial vein of the neck that plays an important role in venous drainage of the anterior neck region.

Anterior lateral nasal branch of anterior ethmoidal artery

The anterior lateral nasal branch of the anterior ethmoidal artery is a small but important vessel supplying part of the external nose and nasal cavity.

Anterior ligament of malleus

The anterior ligament of malleus is a small but important ligament within the middle ear that helps stabilize the malleus, one of the three auditory ossicles.

Anterior limb of internal capsule

The anterior limb of the internal capsule is a crucial white matter structure in the brain, containing important neural pathways.

Anterior lobe of cerebellum

The anterior lobe of the cerebellum is a major division of the cerebellum that plays a vital role in coordinating body movements, especially related to posture and gait.

Anterior longitudinal ligament

The anterior longitudinal ligament (ALL) is a strong, important ligament running along the front (anterior) surface of the vertebral bodies.

Anterior mallear fold

The anterior mallear fold is a small anatomical structure in the middle ear, important for its role in the anatomy of the tympanic cavity.

Anterior medial frontal branches

The anterior medial frontal branches generally refer to the small arterial branches supplying the medial frontal region of the brain, typically arising from the anterior cerebral artery (ACA).

Anterior membranous ampulla

The anterior membranous ampulla is a structure in the inner ear associated with the vestibular system, which helps maintain balance and spatial orientation.

Anterior meningeal artery

The anterior meningeal artery is a small but important artery that supplies the meninges, the protective coverings of the brain.

Anterior meningeal branch of anterior ethmoidal artery

The anterior meningeal branch of the anterior ethmoidal artery is a small but important vessel supplying the meninges in the anterior cranial fossa.

Anterior meningeal branch of vertebral artery

The anterior meningeal branch of the vertebral artery is a small but important artery that supplies parts of the meninges in the posterior cranial fossa.

Anterior nares (nostril)

The anterior nares (also called nostrils) are the external openings of the nasal cavity.

Anterior nasal spine

The anterior nasal spine is an important bony landmark located at the base of the nasal cavity.

Anterior olfactory nucleus

The anterior olfactory nucleus is an important structure in the olfactory (smell) pathway of the brain.

Anterior parietal (postcentral sulcal) artery

The anterior parietal artery, also called the postcentral sulcal artery, is a branch of the middle cerebral artery (MCA) supplying the parietal lobe of the brain.

Anterior parietal artery

The anterior parietal artery is a key branch of the middle cerebral artery (MCA) supplying part of the parietal lobe.

Anterior perforated substance

The anterior perforated substance is an important area at the base of the brain involved in vascular and neural functions.

Anterior pontomesencephalic vein

The anterior pontomesencephalic vein is a cerebral vein involved in venous drainage of the brainstem region.

Anterior process of malleus

The anterior process of the malleus is a small bony projection of the malleus bone in the middle ear.

Anterior ramus of lateral sulcus (of Sylvius)

The anterior ramus of the lateral sulcus (of Sylvius) is a key anatomical feature of the brain’s surface involved in dividing important cortical regions.

Anterior scalene muscles

The anterior scalene muscles are key muscles in the neck involved in movement and respiration.

Anterior semicircular canal and duct

The anterior semicircular canal and duct are key components of the inner ear’s vestibular system, which helps with balance and spatial orientation.

Anterior semicircular canals

The anterior semicircular canal is one of the three semicircular canals in the inner ear that play a crucial role in balance and spatial orientation.

Anterior semicircular duct

The anterior semicircular duct is part of the membranous labyrinth inside the anterior semicircular canal in the inner ear.

Anterior septal branch of anterior ethmoidal artery

The anterior septal branch of the anterior ethmoidal artery is a small but important artery supplying the nasal septum.

Anterior spinal artery

The anterior spinal artery is a crucial blood vessel that supplies the spinal cord.

Anterior spinal vein

The anterior spinal vein is one of the longitudinal veins that drain blood from the spinal cord, working alongside the anterior spinal artery in the anterior median fissure of the spinal cord.

Anterior superficial cervical nodes (anterior jugular nodes)

The anterior superficial cervical lymph nodes, also known as anterior jugular nodes, are part of the superficial lymphatic system of the neck.

Anterior superior alveolar arteries

The anterior superior alveolar arteries are small but vital branches that supply the upper (maxillary) front teeth, part of the maxillary sinus, and adjacent structures.

Anterior superior alveolar nerve

The anterior superior alveolar nerve is a sensory branch of the infraorbital nerve, which itself comes from the maxillary nerve (CN V2) — part of the trigeminal nerve (cranial nerve V).

Anterior temporal branch

The anterior temporal branch refers to a branch of the superficial temporal artery or sometimes the facial nerve, depending on the context. Here's a breakdown of both interpretations:

Anterior temporal diploic vein

The anterior temporal diploic vein is one of the diploic veins located within the diploë (the spongy bone) of the cranial bones. These veins are part of the venous drainage system of the skull and communicate with both intracranial and extracranial veins.

Anterior tributaries of a vorticose vein

The anterior tributaries of a vorticose vein (also called vortex veins or vorticose tributaries) are small choroidal veins in the eye that drain the anterior part of the choroid and ultimately contribute to the venous outflow of the eyeball.

Anterior tubercle

The anterior tubercle is a term used in anatomy to describe a prominent bony projection found in several locations, depending on context.

Anterior tympanic artery

The anterior tympanic artery is a small but important artery involved in supplying the middle ear.

Anterior vagal trunk

The anterior vagal trunk is a branch of the vagus nerve (cranial nerve X) that plays a key role in parasympathetic innervation of abdominal organs, especially around the foregut.

Anterior vein of caudate nucleus

The anterior vein of the caudate nucleus is a small but important deep cerebral vein that drains part of the caudate nucleus, a key structure of the basal ganglia involved in motor control, learning, and cognition.

Anterior vein of septum pellucidum

The anterior vein of the septum pellucidum is a small deep cerebral vein that drains the septum pellucidum, a thin membrane separating the lateral ventricles in the brain.

Anterior vertebral veins

The anterior vertebral veins are part of the vertebral venous system, a complex network of interconnected valveless veins that provide venous drainage from the spinal cord, vertebrae, and surrounding structures.

Anterolateral central (lenticulostriate) arteries

The anterolateral central arteries, also known as the lenticulostriate arteries, are small but critically important perforating arteries that arise from the middle cerebral artery (MCA) and supply deep structures in the brain.

Anteromedial central arteries

The anteromedial central arteries are a group of small perforating arteries that supply deep, midline brain structures. These arteries are crucial for the vascularization of parts of the basal ganglia, hypothalamus, and anterior limb of the internal capsule.

Anteromedian medullary vein

The anteromedian medullary vein is part of the venous drainage system of the brainstem, specifically the medulla oblongata.

Anteroposterior

The term anteroposterior (often abbreviated AP) describes a directional orientation or plane in anatomy and imaging. It is the forward region of a rear sectioning, space, locale, or plane.

Antihelix

The antihelix is a prominent anatomical feature of the external ear (auricle).

Antitragus

The antitragus is a small but important anatomical feature of the external ear (auricle).

Anulus fibrosus

The anulus fibrosus (or annulus fibrosus) is a key structural component of an intervertebral disc in the spine.

Aorta

The aorta is the largest artery in the human body. It plays a critical role in the circulatory system by transporting oxygen-rich blood from the left ventricle of the heart to the rest of the body.

Aortic arch

The aortic arch is the curved, middle portion of the aorta that connects the ascending aorta (which comes out of the heart) to the descending aorta (which runs down through the chest and abdomen).

Apex of cuneus

The apex of the cuneus refers to the front (anterior) tip of the cuneus, which is a wedge-shaped region of the occipital lobe in the brain.

Apex of tongue

The apex of the tongue is the tip or frontmost part of your tongue.

Apical collecting vessels

The term apical collecting vessels refers to lymphatic vessels that drain lymph (a clear fluid containing immune cells and waste products) from the apex (top region) of an organ or structure.

Apical foramina

The apical foramen (plural: apical foramina) is an important structure at the tip (apex) of the root of a tooth.

Apical ligament of dens

The apical ligament of the dens is a small but important ligament located deep in the upper part of your neck, inside the skull base region. It helps stabilize the connection between the skull and the top of the spine.

Appendix

The appendix — more precisely called the vermiform appendix — is a small, narrow, tube-shaped pouch attached to the beginning of the large intestine (the cecum) in the lower right part of your abdomen.

Arachnoid

The arachnoid (or arachnoid mater) is one of the three protective membranes, called the meninges, that surround your brain and spinal cord.

Arachnoid granulation

An arachnoid granulation (also called an arachnoid villus when small) is a small, mushroom-shaped projection of the arachnoid mater (the middle meningeal layer) that extends into the dural venous sinuses, especially the superior sagittal sinus of the brain.

Arachnoid-dura interface (site of subdural hematoma)

The arachnoid–dura interface (also called the subdural space or dural–arachnoid junction) is the potential space and connection between the dura mater (the tough outer meningeal layer) and the arachnoid mater (the delicate middle layer) that cover the brain and spinal cord.

Arch of cricoid cartilage

The arch of the cricoid cartilage is a specific part of the cricoid cartilage, which is a ring-shaped structure in the larynx (voice box).

Arcuate (infundibular) nuclei of hypothalamus

The arcuate nucleus (also called the infundibular nucleus) is a cluster of neurons in the hypothalamus that plays a crucial role in regulating appetite, metabolism, and hormone secretion.

Arcuate eminence of petrous part of temporal bone

The arcuate eminence is a prominent, rounded elevation on the superior surface of the petrous part of the temporal bone. It is an important anatomical landmark in the middle cranial fossa of the skull.

Area for articulation of left uncinate process of C4

The uncinate process is a hook-like projection found on the lateral edges of the superior surface of the cervical vertebral bodies (C3–C7).

Arterial supply of face

The arterial supply of the face comes mainly from branches of the external carotid artery, with a smaller contribution from the internal carotid artery via the ophthalmic artery.

Arteries of iris

The arteries of the iris are small branches that supply blood to the iris.

Arteries of orbit and eyelids

The arteries of the orbit and eyelids are small branches that supply blood to the orbit and eyelids.

Arteries of brain

The brain’s blood supply comes from two main pairs of arteries. They are the internal carotid arteries, or the ICA, and the vertebral arteries. The ICA comes from the anterior circulation of the brain, and the vertebral arteries come from the posterior circulation of the brain.

Arteries of nasal cavity

The nasal cavity has a rich arterial blood supply coming from both the internal carotid and external carotid systems.

Arteries of posterior cranial fossa

The arteries of the posterior cranial fossa supply the brainstem, cerebellum, meninges, and bone of the posterior part of the skull base.

Arteries to brain

The arteries that lead to the brain are the main blood vessels that bring oxygenated blood into the cranial cavity to supply the entire brain.

Arteries to meninges

The arteries to the meninges (the coverings of the brain and spinal cord) supply blood mainly to the dura mater, since the arachnoid has no blood vessels and the pia mater receives small branches from brain and spinal arteries.

Artery of pterygoid canal

The artery of the pterygoid canal (also called the Vidian artery) is a small but important branch associated with the pterygoid canal in the base of the skull.

Artery of trabecula

The artery of the trabecula is a blood passage that leads from the heart to the trabeculae. A trabecula, itself, is a small, beam-like structure that appears in various organs and tissues. It usually refers to a supporting or structural element within a spongy or mesh-like tissue.

Artery to frenulum

The frenulum is a small fold of tissue that connects a mobile structure (like the tongue, lips, or prepuce) to the underlying tissue. Its blood supply comes from nearby arteries that serve the associated region.

Articular branch of mandibular nerve

The articular branch of the mandibular nerve is a small sensory nerve branch that supplies part of the temporomandibular joint (TMJ).

Articular cartilage on dens for median atlanto axial joint complex

The median atlanto-axial joint is a pivot-type synovial joint between the dens (odontoid process) of the axis (C2), and the anterior arch of the atlas (C1). This joint allows the rotation of the head (shaking the head “no”). The dens of the second cervical vertebrae possesses a smooth, convex articular surface on its forward face, and along that face there is cartilage (hyaline cartilage) that serves to reduce friction and allow for smooth movement of the head.

Articular disc

An articular disc is a fibrocartilaginous structure found within certain synovial joints.

It divides the joint cavity partially or completely into two separate spaces, improving the fit between the articulating bones and helping the joint move smoothly.

Articular disc of temporomandibular joint

The articular disc of the TMJ is a thin, oval plate of fibrocartilage that lies between the mandibular condyle and the mandibular fossa of the temporal bone. It divides the TMJ cavity into two separate synovial compartments: upper (superior) compartment - for gliding (translation) movements and lower (inferior) compartment - for hinge (rotation) movements.

Articular facet for dens

The articular facet for the dens (also called the facet for the odontoid process) is a smooth, oval surface located on the posterior aspect of the anterior arch of the atlas (C1).

Articular pillar formed by articular processes and interarticular parts

The articular pillar is a vertical column of bone on the lateral part of a vertebra, formed by the superior and inferior articular processes and the bone between them (the pars interarticularis or interarticular part).

Articular surface

An articular surface is the smooth area of a bone that comes into contact with another bone at a joint (articulation).

Articular surface of uncinate processes

The uncinate process is a hook-like bony projection found on the superolateral margin (upper side edge) of the body of a cervical vertebra (typically C3–C7). Each cervical vertebral body has two uncinate processes — right and left. These processes curve upward from the lateral edges of the superior surface of the vertebral body.

Articular tubercle

The “articular tubercle” (also called the articular eminence) is an important structure of the temporal bone, especially in the temporomandibular joint (TMJ).

Aryepiglottic fold

The aryepiglottic fold is a very important structure in the larynx (voice box) and is key to understanding how the laryngeal inlet is formed and protected during swallowing.

Aryepiglottic muscle

The aryepiglottic muscle is a small but very important intrinsic muscle of the larynx, closely related to the aryepiglottic.

Arytenoid articular surface of cricoid cartilage

The arytenoid articular surface of the cricoid cartilage is an important part of laryngeal cartilage anatomy, especially for understanding how the arytenoid cartilages move on the cricoid cartilage during speech and breathing.

Arytenoid cartilage

The arytenoid cartilages are paired, small, pyramid-shaped cartilages in the larynx. They sit on the posterior, upper border of the cricoid cartilage and are essential for controlling the vocal cords.

Ascending aorta

The ascending aorta is the first portion of the aorta, the largest artery in the body, that arises from the left ventricle of the heart.

Ascending cervical artery

The ascending cervical artery is a small artery in the neck that supplies muscles and vertebral structures of the cervical region. It is usually a branch of the inferior thyroid artery, which itself comes from the thyrocervical trunk (branch of the subclavian artery).

Ascending colon

The ascending colon is the first main portion of the large intestine that rises on the right side of the abdomen. It connects the cecum to the transverse colon and is part of the colon (large intestine) responsible for absorbing water and electrolytes and storing fecal matter.

Ascending palatine artery

The ascending palatine artery is a small branch of the facial artery that ascends along the side of the pharynx and palate, supplying palatine muscles, soft palate, and pharyngeal walls. It is important in blood supply to the palate and pharynx and participates in anastomoses with other arteries of the region.

Ascending pharyngeal artery

The ascending pharyngeal artery is a small but important branch of the external carotid artery. It ascends along the pharynx and supplies the pharyngeal wall, prevertebral muscles, meninges, and surrounding structures. It is one of the deepest branches of the external carotid artery.

Ascending ramus of lateral sulcus (of Sylvius)

The ascending ramus of the lateral sulcus is a neuroanatomical structure in the cerebral cortex.

Atlantoaxial joint

The atlantoaxial joint is a synovial joint between the first cervical vertebra (atlas, C1) and the second cervical vertebra (axis, C2). It allows rotation of the head.

Atlas (C1)

The atlas is the first cervical vertebra (C1) of the spine.

Atrium of middle nasal meatus

The atrium of the middle nasal meatus is a small recessed area in the lateral wall of the nasal cavity, located anterior to the ethmoidal bulla. It serves as a passageway or “entry hall”” for drainage from the frontal sinus and anterior ethmoidal air cells into the middle nasal meatus.

Auditory (pharyngotympanic, Eustachian) tube

The auditory tube is a canal connecting the middle ear cavity to the nasopharynx. Its main function is to equalize air pressure on both sides of the tympanic membrane (eardrum) and to drain secretions from the middle ear into the nasopharynx.

Auditory tube lumen

The auditory tube lumen is the internal cavity or passageway of the auditory (Eustachian) tube through which air and secretions pass between the middle ear and nasopharynx.

Auricle

The auricle is the external, visible part of the ear that projects from the side of the head. Its main function is to collect and funnel sound waves into the external auditory canal toward the tympanic membrane (eardrum).

Auricular branch of vagus nerve

The auricular branch of the vagus nerve (also called Arnold’s nerve) is a small sensory branch of the vagus nerve (cranial nerve X). It supplies sensation to part of the external ear, external auditory canal, and part of the tympanic membrane.

Auricular cartilage

The auricular cartilage is the elastic cartilage that forms the framework of the auricle (external ear/pinna). It gives the auricle its shape, flexibility, and resilience, while supporting the external auditory canal.

Auricular tubercle (of Darwin)

The auricular tubercle (also called tubercle of Darwin) is a small, congenital elevation on the outer rim (helix) of the auricle.

Auricularis anterior muscle

The auricularis anterior is a small, thin muscle of the scalp and ear. It attaches the auricle (external ear) to the temporal region of the head and helps move the auricle slightly forward.

Auricularis posterior muscle

The auricularis posterior is a small, thin muscle located behind the auricle (external ear). It connects the auricle to the mastoid region of the skull and pulls the ear backward. It is one of the three auricular muscles (anterior, superior, posterior), most humans have minimal voluntary control over it.

Auricularis superior muscle

The auricularis superior is a thin, small muscle located above the auricle (external ear). It connects the upper part of the auricle to the epicranial aponeurosis and elevates the ear slightly. It is one of the three auricular muscles (anterior, superior, posterior), and in humans, it has minimal voluntary movement compared to some animals.

Auriculotemporal nerve

The auriculotemporal nerve is a branch of the mandibular nerve (V3, the third division of the trigeminal nerve, CN V). It is primarily a sensory nerve, but also carries postganglionic parasympathetic fibers to the parotid gland. It supplies sensation to the temple, external ear, anterior auricle, external acoustic meatus, tympanic membrane, and temporomandibular joint.

Autonomic innervation of nasal cavity

The nasal cavity receives both sympathetic and parasympathetic fibers, which control: glandular secretion (mucus production) and vasoconstriction and vasodilation (blood flow to nasal mucosa - affecting congestion). The sympathetic fibers are mainly vasomotor, and the parasympathetic fibers are mainly secretomotor.

Autonomic nerves in head

The head receives autonomic (sympathetic and parasympathetic) innervation that controls: lacrimal glands, salivary glands, nasal glands, and palatal glands as well as vasoconstriction blood vessels, vasodilation blood vessels and the smooth muscles of the iris, ciliary body, and piloerector muscles. The parasympathetic fibers mainly control the secretomotor glands and also constrict the pupils. The sympathetic fibers mainly control the vasomotor glands and also dilate the pupils, raise the eyelids, and innervate the sweat glands.

Autonomic nerves in neck

The neck receives autonomic innervation that controls the smooth muscles of blood vessels (vasoconstriction/vasodilation), glands (salivary, thyroid, parathyroid, mucous glands of pharynx), and visceral functions (heart, trachea, esophagus, thoracic inlet structures). Parasympathetic fibers mainly come from cranial nerves (IX and X), and sympathetic fibers come from cervical sympathetic ganglia.

Axillary artery

The axillary artery is a continuation of the subclavian artery that runs through the axilla (armpit region). It supplies blood to the shoulder, axilla, and upper limb. It is the main artery of the axilla, giving off multiple branches to muscles, shoulder, chest wall, and humerus.

Axis (C2)

The axis is the second cervical vertebra (C2) of the spine.

Axis of lens

The axis of the lens refers to an imaginary line that passes through the center of the lens of the eye, extending from the anterior surface to the posterior surface. It helps describe the orientation of the lens relative to the optical axis of the eye.

Basal collecting vessels

The basal collecting vessels are lymphatic vessels that drain lymph from the base of an organ or tissue, particularly from glands or epithelial surfaces.

Basal nuclei (ganglia)

The basal nuclei, also called the basal ganglia, are collections of gray matter (neuronal cell bodies) located deep within the cerebral hemispheres.

Basal vein

The basal vein, also known as the basal vein of Rosenthal, is a deep cerebral vein that drains deep structures of the cerebral hemisphere, especially around the base of the brain.

Base of mandible

The base of the mandible is the lower border of the mandibular body, forming the inferior margin of the jawbone.

Base of skull

The base of the skull (cranial base or skull base) is the lower part of the skull that forms the floor of the cranial cavity and separates the brain from the structures of the face and neck.

Base of stapes in fossa of oval (vestibular) window

The base (footplate) of the stapes fits into the fossa ovalis, also called the oval window (vestibular window) — a small opening on the medial wall of the middle ear that leads into the vestibule of the inner ear.

Basilar artery

The basilar artery is a midline artery located on the anterior (ventral) surface of the pons. It is formed by the union of the two vertebral arteries at the lower border of the pons and supplies blood to the pons, cerebellum, and posterior part of the brain.

Basilar membrane

The basilar membrane is a flexible, fibrous membrane inside the cochlea of the inner ear that separates the scala media (cochlear duct) from the scala tympani.

Basilar part of occipital bone

The basilar part of the occipital bone is the thick, quadrilateral portion of the occipital bone that lies in front of the foramen magnum.

Basilar venous plexus

The basilar venous plexus is a network of interconnected veins located on the anterior (basilar) surface of the clivus — the part of the basilar occipital bone and upper sphenoid.

Basivertebral vein

The basivertebral vein is a vein located within the body of a vertebra that plays an important role in the venous drainage of the vertebral column.

Bed of parotid gland

The bed of the parotid gland refers to the structures that lie deep to (beneath) the parotid gland, forming the surface on which the gland rests in the parotid region of the face.

Bifid spinous process

The bifid spinous process is a split (forked) posterior projection of a vertebra that serves as an attachment point for muscles and ligaments of the neck.

Bipolar cells

Bipolar cells are a type of neuron that serve as interneurons, connecting sensory receptor cells to ganglion cells (or other neurons) — they act as a relay in the transmission of sensory information.

Biventer lobule of posterior lobe of cerebellum

The biventer lobule (also called the biventer lobule of the posterior lobe of the cerebellum) is a distinct part of the cerebellar hemisphere located on the inferior surface of the posterior lobe of the cerebellum.

Blood vessels of ciliary body

The blood vessels of the ciliary body form an important part of the uveal circulation of the eye (which also includes the iris and choroid). They supply nutrients to the ciliary processes, ciliary muscle, and are responsible for aqueous humor formation.

Bodies of cervical vertebrae

The bodies of the cervical vertebrae are a key part of the vertebral column, especially in supporting the head and allowing neck mobility.

Body

The body of something is its general structure or form.

Body of axis (C2)

The body of the axis, also called the body of the second cervical vertebra (C2), is the large, strong, anterior portion of the C2 bone.

Body of C3

The body of C3 is the anterior, weight-bearing portion of the third cervical vertebra. It forms part of the cervical spine and helps support the head, transmit weight, and protect the spinal cord.

Body of caudate nucleus

The body of the caudate nucleus is the middle portion of the caudate nucleus, one of the major basal nuclei (basal ganglia) of the brain.

Body of fornix

The body of the fornix is the central part of the fornix, a C-shaped bundle of white matter fibers in the brain that connects the hippocampus to other structures of the limbic system, especially the mammillary bodies and septal area.

Body of hyoid bone

The body of the hyoid bone is the central and largest part of the hyoid bone, which lies in the anterior neck at the level of the C3 vertebra, between the mandible and the thyroid cartilage.

Body of mandible

The body of the mandible is the horizontal, curved portion of the mandible (lower jawbone) that forms the base of the lower face. It holds the lower teeth and gives attachment to several facial and masticatory muscles.

Body of sphenoid bone

The body of the sphenoid bone is the central part of the sphenoid bone, located in the middle cranial fossa.

Body of tongue

The body of the tongue is the anterior two-thirds (front part) of the tongue, located in the oral cavity proper.

Bone

A bone is a rigid organ that forms part of the skeletal system. It is made of living tissue that provides support, protection, movement, and mineral storage for the body.

Bones of nasal cavity

The nasal cavity is a pyramid-shaped space within the skull, extending from the nostrils (anteriorly) to the choanae (posteriorly).

Bony and membranous labyrinths

The bony and membranous labyrinths are key structures of the inner ear responsible for hearing and balance.

Bony canal

A bony canal is a tubular passage or tunnel-like channel within bone through which nerves, blood vessels, or other structures pass.

Bony spicule dividing foramen transversarium

A bony spicule dividing the foramen transversarium refers to a thin bony ridge or bar that partially or completely subdivides the foramen transversarium into two compartments.

Brachia of superior and inferior colliculi

The brachia of the superior and inferior colliculi are key fiber tracts in the midbrain (mesencephalon) that connect the colliculi (reflex centers for vision and hearing) with higher sensory nuclei.

Brachial plexus

The brachial plexus is a network of nerves formed by the ventral rami of the spinal nerves C5–T1, which supplies the shoulder, arm, forearm, and hand. It allows motor control of muscles and sensory perception from the upper limb.

Brachiocephalic trunk

The brachiocephalic trunk (also called brachiocephalic artery or innominate artery) is the first and largest branch of the aortic arch. It supplies blood to the right side of the head, neck, and right upper limb.

Brachiocephalic veins

The brachiocephalic veins (also called innominate veins) are paired veins — right and left — that are formed by the union of the internal jugular vein and subclavian vein on each side.

Brachium of inferior colliculus

The brachium of the inferior colliculus (also called inferior brachium) is a bundle of nerve fibers that connects the inferior colliculus (midbrain) with the medial geniculate body (thalamus).

Brachium of superior colliculus

The brachium of the superior colliculus (also called superior brachium) is a bundle of nerve fibers connecting the superior colliculus (midbrain) with the lateral geniculate body and other visual centers.

Brain

The brain is the central organ of the nervous system located in the cranial cavity, protected by the skull, meninges, and cerebrospinal fluid (CSF). It controls voluntary and involuntary actions, senses, thoughts, memory, and emotions.

Brainstem

The brainstem is the posterior part of the brain that connects the cerebrum with the spinal cord. It controls vital autonomic functions, cranial nerve functions, and acts as a conduit for ascending (sensory) and descending (motor) pathways.

Branch to angular gyrus

The angular gyrus is a region in the inferior parietal lobule of the dominant (usually left) hemisphere, near the junction of the parietal, temporal, and occipital lobes. It is primarily involved in language, number processing, reading, and spatial cognition. The ‘branches’ which supply it with functionality come from the arterial, veinal, and nervous systems of the body.

Branch to thyrohyoid muscle

The thyrohyoid muscle is a small infrahyoid (strap) muscle that runs from the thyroid cartilage to the hyoid bone. Its main action is to depress the hyoid bone or elevate the larynx during swallowing. The ‘branches’ which supply it with functionality come from the arterial, veinal, and nervous systems of the body.

Branches from cervical plexus

The cervical plexus is a key network of nerves in the neck, formed by the ventral rami of C1–C4 spinal nerves. The ‘branches’ which supply it with functionality come from the arterial, veinal, and nervous systems of the body.

Branches of facial nerve

The facial nerve (cranial nerve VII) is one of the most important mixed cranial nerves, responsible for facial expression, taste, and glandular secretion. The ‘branches’ which supply it with functionality come from the arterial, veinal, and nervous systems of the body.

Branches of middle meningeal artery

The middle meningeal artery is one of the most important arteries of the cranial cavity, because it supplies the dura mater and calvaria. The ‘branches’ which supply it with functionality come from the arterial, veinal, and nervous systems of the body.

Branches to auricular muscles

The auricular muscles are small muscles around the external ear (auricle or pinna). Though they are often rudimentary in humans, they are more functional in many animals (for ear movement). The ‘branches’ which supply it with functionality come from the arterial, veinal, and nervous systems of the body.

Branches to inferior and medial rectus muscles of the eye

The inferior rectus and medial rectus muscles of the eye are two of the six extraocular muscles that control eye movement. The ‘branches’ which supply it with functionality come from the arterial, veinal, and nervous systems of the body.

Bregma

The bregma is the point on the skull where the coronal and sagittal sutures meet. It marks the junction of the two parietal bones with the frontal bone.

Bridging vein

Bridging veins are thin-walled veins that connect the superficial cerebral veins (on the surface of the brain) to the dural venous sinuses (mainly the superior sagittal sinus and others).

Bronchi

The bronchi (singular: bronchus) are air-conducting tubes that branch from the trachea and deliver air to each lung. They form part of the lower respiratory tract, along with the trachea, bronchioles, and lungs.

Buccal artery

The buccal artery (also called the buccinatory artery) is a small branch of the maxillary artery, one of the terminal branches of the external carotid artery. It primarily supplies blood to the cheek region, especially the buccinator muscle and oral mucosa.

Buccal branches

The buccal branches are the arterial, veinal, and nervous connections which stem from the maxillary artery - a terminal branch of the external carotid artery.

Buccal nerve

The buccal nerve, also known as the long buccal nerve, is an important sensory branch of the mandibular nerve (CN V₃) that supplies the cheek region.

Buccinator

The buccinator muscle is a thin, flat muscle in the cheek, forming the muscular part of the cheek wall. It’s a facial expression muscle but also plays an important role in mastication (chewing).

Buccinator crest of mandible

The buccinator crest of the mandible is a small but important bony ridge related to the buccinator muscle.

Buccinator facial nodes

The buccinator (facial) nodes — also called facial lymph nodes or buccal lymph nodes — are small superficial lymph nodes located on the cheek, associated with the buccinator muscle and facial vein.

Buccopharyngeal fascia

The buccopharyngeal fascia is a thin but important connective tissue layer in the neck and face, forming part of the deep cervical fascia. It covers the buccinator and pharyngeal muscles, creating a smooth surface that allows structures in the mouth and pharynx to move easily during swallowing and speaking.

Bulb of vorticose (choroid) vein

The bulb of the vorticose vein is a small anatomical feature associated with the vorticose veins (vortex veins) of the eye.

Bulbar conjunctiva

The bulbar conjunctiva is a key part of the conjunctiva, the thin, transparent membrane that lines the inside of the eyelids and covers the white part of the eye.

Bulbar conjunctival vessels

The bulbar conjunctival vessels are the blood vessels located in the bulbar conjunctiva, the thin membrane covering the anterior part of the sclera.

Bulging septum

The bulging septum refers to the localized protrusion or convexity of the nasal septum into one of the nasal cavities. Essentially, part of the septum — the cartilage and bone that divides the nose into left and right sides — bulges inward, narrowing the airway.

The C1 is the first cervical vertebra of the spine, also called the atlas. It is a ring-shaped bone located at the very top of the vertebral column, just below the skull, and it plays a vital role in supporting the head and allowing nodding and rotation movements.

C1 spinal nerve

The C1 spinal nerve is the first cervical spinal nerve, and it’s the highest (most superior) spinal nerve in the body. It plays a crucial role in the motor control of neck muscles - particularly those near the base of the skull.

The C2 (second cervical vertebra) — also called the axis — is the second bone in the cervical spine, located just below the atlas (C1) and above the C3 vertebra. It plays a key role in allowing the head to rotate from side to side.

C2 spinal nerve

The C2 spinal nerve is the second cervical spinal nerve, emerging from the spinal cord between the first (C1, atlas) and second (C2, axis) cervical vertebrae. It is a mixed nerve, meaning it carries both sensory and motor fibers, and it plays an important role in neck movement and sensation to the scalp and upper neck.

The C3 is the third cervical vertebra of the spinal column — part of the neck (cervical) region. It lies below C2 (the axis) and above C4, forming part of the upper cervical spine that supports the head, allows neck movement, and protects the spinal cord.

C3 inferior aspect

The inferior aspect of the C3 vertebra refers to the lower surface and structures on the underside of the third cervical vertebra — the part that connects it to the C4 vertebra below. It includes features that allow articulation, support, and passage of nerves and blood vessels between the vertebrae.

C3 spinal nerve

The C3 spinal nerve is the third cervical spinal nerve, one of the eight cervical nerves (C1–C8) that emerge from the spinal cord in the neck region. It exits the spinal canal between the C2 and C3 vertebrae, and like all spinal nerves, it is a mixed nerve — carrying both motor (movement) and sensory (sensation) fibers.

The C4 is the fourth cervical vertebra in the spine, located in the middle of the neck. It lies below C3 and above C5, forming part of the cervical spine (C1–C7) — the most flexible region of the vertebral column, responsible for supporting the head and allowing neck movement.

C4 spinal nerve

The C4 spinal nerve is the fourth cervical spinal nerve, one of the eight cervical nerves (C1–C8) that emerge from the spinal cord in the neck region. It exits the spinal canal between the C3 and C4 vertebrae, and like all spinal nerves, it is a mixed nerve — carrying both motor (movement) and sensory (sensation) fibers.

C4 Superior aspect

The superior aspect of the C4 vertebra refers to the top surface of the fourth cervical vertebra, which articulates with the inferior aspect of the C3 vertebra above. This surface is important for spinal stability, weight transmission, and movement of the neck.

The C5 is the fifth cervical vertebra in the neck portion of the spinal column. It lies below C4 and above C6, forming part of the cervical spine (C1–C7). Like other cervical vertebrae, it supports the head, allows neck movement, and protects the spinal cord.

C5 spinal nerve

The C5 spinal nerve is the fifth cervical spinal nerve, one of the eight cervical nerves (C1–C8) that emerge from the spinal cord in the neck. It exits the spinal canal between the C4 and C5 vertebrae. Like all spinal nerves, it is a mixed nerve, carrying both motor and sensory fibers. It is especially important because it contributes to the brachial plexus, which innervates the upper limb.

The C6 is the sixth cervical vertebra of the spinal column — part of the cervical (neck) spine, which includes seven vertebrae (C1–C7). It lies below C5 and above C7, forming a crucial link between the upper and lower neck. C6 is considered a typical cervical vertebra, though it has one distinctive landmark: the carotid tubercle, a prominent feature on its anterior transverse process.

The C7 is the seventh cervical vertebra, the lowest vertebra in the cervical (neck) spine. It lies below C6 and above the first thoracic vertebra (T1). It is also known as the vertebra prominens, because its long spinous process can be easily felt through the skin at the base of the neck — making it a key anatomical landmark.

Calcar avis

The calcar avis is a ridge (internal elevation) on the medial wall of the posterior horn of the lateral ventricle in the brain. It is formed by the indentation of the calcarine sulcus — a deep groove on the medial surface of the occipital lobe — pushing into the ventricular cavity from the outside.

Calcarine branch

The calcarine branch (or calcarine artery) is an important terminal branch of the posterior cerebral artery (PCA) that supplies the primary visual cortex in the occipital lobe.

Calcerine sulcus

The calcarine sulcus (also called the calcarine fissure) is a deep groove on the medial surface of the occipital lobe of the brain. It is one of the most important sulci because it houses the primary visual cortex (Brodmann area 17) — the brain’s main visual processing center.

Callosomarginal artery

The callosomarginal artery is one of the major branches of the anterior cerebral artery (ACA). It runs along the cingulate sulcus and supplies blood to the medial surface of the frontal and parietal lobes, especially regions involved in motor control of the lower limbs.

Calvaria

The calvaria (also called the skullcap) is the upper part of the skull that encloses and protects the brain. It forms the roof of the cranial cavity, and includes portions of several cranial bones that are tightly joined by sutures.

Capillary plexus of infundibular process

The capillary plexus of the infundibular process refers to the rich network of fenestrated capillaries located in the posterior pituitary (neurohypophysis)—specifically within the infundibular process, which is the lower, bulbous part of the pituitary stalk.

Capsule of atlantoocipital joint

The capsule of the atlanto-occipital joint is a thin, loose, fibrous articular capsule that surrounds and encloses each atlanto-occipital joint (there is one on the left and one on the right).

Capsule of lateral atlantoaxial joint

The capsule of the lateral atlanto-axial joint is the fibrous articular capsule that encloses each of the two synovial joints between the inferior articular facets of the atlas (C1) and the superior articular facets of the axis (C2).

Capsule of lens

The capsule of the lens is a smooth, transparent, highly elastic basement membrane that completely surrounds the lens of the eye.

Capsule of zygapophyseal joint (C2-3)

The capsule of the zygapophyseal (facet) joint between C2 and C3 is the fibrous articular capsule that encloses the synovial joint formed by the inferior articular process of C2 and the superior articular process of C3.

Capsule of zygapophyseal joint (C3-4)

The capsule of the zygapophyseal (facet) joint between C3 and C4 is a fibrous articular capsule that encloses the synovial joint formed by the inferior articular process of C3 and the superior articular process of C4.

Cardiac plexus

The cardiac plexus is the autonomic nerve network located at the base of the heart that regulates heart rate, conduction, and coronary vessel tone. It is formed by sympathetic and parasympathetic fibers that converge and then distribute along the coronary arteries and conduction system.

Caroticotympanic branch of internal carotid artery

The caroticotympanic branches of the internal carotid artery (ICA) are small, delicate arterial branches that arise from the petrous segment of the ICA and enter the tympanic cavity.

Caroticotympanic nerve

The caroticotympanic nerve is a small sympathetic branch that enters the tympanic cavity and participates in forming the tympanic plexus.

Carotid autonomic plexus of carotid canal

The carotid autonomic plexus of the carotid canal refers to the internal carotid plexus, the sympathetic nerve network that surrounds the internal carotid artery (ICA) as it travels through the carotid canal in the petrous temporal bone.

Carotid body

The carotid body is a small, highly vascular chemoreceptor organ located at the bifurcation of the common carotid artery. Its primary function is to detect changes in blood oxygen, carbon dioxide, and pH and regulate respiratory and cardiovascular responses.

Carotid branch of glossopharyngeal nerve

The carotid branch of the glossopharyngeal nerve is also called Hering’s nerve. It is a small, specialized branch of cranial nerve IX (glossopharyngeal nerve) that provides sensory innervation to the carotid sinus and carotid body.

Carotid branch of glossopharyngeal nerve (IX)

Carotid canal

The carotid canal is a bony passage in the temporal bone that allows the internal carotid artery (ICA), along with accompanying sympathetic nerves, to pass from the neck into the cranial cavity. It is a key anatomical landmark in the skull base.

Carotid canal (external opening) of temporal bone

The external opening of the carotid canal is the inferior (external) entry point of the carotid canal on the undersurface of the temporal bone, allowing the internal carotid artery (ICA) to enter the skull.

Carotid canal for internal carotid artery

The carotid canal is the bony passage in the petrous part of the temporal bone through which the internal carotid artery (ICA) enters the cranial cavity from the neck, along with accompanying sympathetic nerves.

Carotid canal for internal carotid nerve plexus

The carotid canal not only transmits the internal carotid artery (ICA) but also carries the internal carotid nerve plexus, a network of postganglionic sympathetic fibers from the superior cervical ganglion. These fibers travel with the artery through the canal to reach the cranial cavity and distribute to head structures.

Carotid groove for internal carotid artery of sphenoid bone

The carotid groove of the sphenoid bone (also called the sulcus for the internal carotid artery) is a shallow groove on the body of the sphenoid bone that accommodates the intracranial portion of the internal carotid artery (ICA) as it passes through the middle cranial fossa.

Carotid nerve (IX) and carotid body

The carotid nerve is a branch of the glossopharyngeal nerve (CN IX), usually from the inferior (petrosal) ganglion, and a carotid body is a small, highly vascular chemoreceptor organ located at the bifurcation of the common carotid artery into the internal and external carotid arteries.

Carotid sheath

The carotid sheath is a tubular fascial compartment in the neck that encloses the major neurovascular structures supplying the head and neck. It extends from the base of the skull to the root of the neck.

Carotid sinus

The carotid sinus is a dilated, baroreceptor-rich segment of the internal carotid artery located at the carotid bifurcation. It is a crucial sensor for arterial blood pressure regulation.

Carotid tubercle

The carotid tubercle (also called Chassaignac’s tubercle) is an important anatomical landmark on the transverse process of the C6 vertebra.

Cartilage of auditory tube

The cartilage of the auditory tube (also called the cartilage of the pharyngotympanic tube or eustachian tube) forms the supporting skeletal framework of the medial two-thirds of the tube that connects the nasopharynx to the middle ear cavity.

Cartilages of larynx

The cartilages of the larynx form the structural framework of the larynx and enable airway protection, phonation, and respiration. There are nine laryngeal cartilages: three unpaired (single) and three paired.

Cartilaginous part of auditory (pharyngotympanic, Eustachian) tube

The cartilaginous part of the auditory tube (also called the pharyngotympanic or Eustachian tube) forms the medial two-thirds of the tube and provides its functional support, shape, and valve mechanism.

Caudate nucleus

The caudate nucleus is one of the major basal ganglia structures of the brain and plays key roles in motor control, learning, habit formation, reward, and several cognitive processes.

Cavernous plexus

The cavernous plexus is a venous network associated with the cavernous sinus located on either side of the sella turcica within the middle cranial fossa. It is made of a dense meshwork of interconnected veins and communicates widely with cranial, orbital, and extracranial venous systems.

Cavernous sinus

The cavernous sinus is a large, dural venous sinus situated on either side of the sella turcica in the middle cranial fossa. It is unique among venous sinuses because it contains major arteries and cranial nerves within its lumen or walls, making it a highly clinically significant structure.

Cavernous sinus branches of meningohypophyseal trunk

The meningohypophyseal trunk (MHT) is a constant branch of the cavernous segment of the internal carotid artery (ICA). It gives rise to several small but clinically important arterial branches that supply the dura, cranial nerves, and pituitary region.

These are collectively called the cavernous sinus branches of the meningohypophyseal trunk.

Cecum

The cecum is the first and widest part of the large intestine, located at the junction of the small and large intestines. It plays a minor role in digestion but is important as a landmark in gastrointestinal anatomy and surgery.

Celiac branches from anterior and posterior vagal trunks to celiac plexus

The vagus nerve (CN X) provides parasympathetic input to the celiac plexus via its anterior and posterior vagal trunks. These fibers travel along the esophagus into the abdomen to influence the foregut and part of the midgut.

Celiac ganglia

The celiac ganglia are the largest prevertebral sympathetic ganglia in the abdomen and serve as a major hub for autonomic innervation of the foregut and part of the midgut. They are closely associated with the celiac plexus.

Celiac plexus

The celiac plexus, also called the solar plexus, is a large autonomic nerve network in the upper abdomen that integrates sympathetic and parasympathetic fibers to innervate most foregut and some midgut organs.

Cement

In anatomy and histology, cement (or cementum) refers to the calcified connective tissue that covers the roots of teeth. It is part of the periodontium, which anchors the tooth to the alveolar bone via the periodontal ligament (PDL).

Central canal of spinal cord

The central canal of the spinal cord is a small, cerebrospinal fluid (CSF)-filled channel that runs along the longitudinal axis of the spinal cord. It is a remnant of the neural tube lumen.

Central collecting vessels

In anatomy and lymphatic terminology, central collecting vessels usually refer to the major lymphatic trunks or vessels that drain lymph from peripheral collecting lymphatics toward the central lymphatic system, such as the thoracic duct or right lymphatic duct. They are part of the central lymphatic pathway.

Central lobule of superior vermis

The central lobule of the superior vermis is a part of the cerebellum, specifically located in the vermal region of the anterior lobe.

Central lobule of vermis of cerebellum

The central lobule of the vermis of the cerebellum is a midline structure in the superior (anterior) vermis, important for truncal coordination and posture.

Central part of left lateral ventricle

The central part of the lateral ventricle is one of the main regions of the lateral ventricles, which are cavities within the cerebral hemispheres that contain cerebrospinal fluid (CSF).

Central retinal artery

The central retinal artery (CRA) is the main arterial blood supply to the inner layers of the retina, entering the eye through the optic nerve. It is a vital vessel for retinal function and vision.

Central retinal vein

The central retinal vein (CRV) is the main venous drainage of the retina, running alongside the central retinal artery through the optic nerve and exiting the eye to drain into the cavernous sinus via the ophthalmic veins.

Central sulcal artery

The central sulcal arteries (plural) are the small cortical branches of the middle cerebral artery (MCA) that penetrate the central sulcus (Rolandic fissure) to supply the primary motor and sensory cortices. They are crucial in maintaining contralateral voluntary motor and somatosensory functions.

Central sulcus (of Rolando)

The central sulcus, also called the fissure of Rolando, is a prominent landmark of the cerebral cortex that separates the frontal and parietal lobes and divides motor and sensory cortical areas.

Central sulcus of insula (island of Reil)

The central sulcus of the insula (also called the insular central sulcus or central insular sulcus) is a sulcus within the insular cortex, which is located deep within the lateral sulcus (Sylvian fissure). It divides the insula into anterior and posterior regions and serves as an important anatomical and functional landmark.

Centromedian

It is an intralaminar thalamic nucleus located within the internal medullary lamina of the thalamus.

Cerebellar nuclei

The cerebellar nuclei (also called the deep cerebellar nuclei) are the major output centers of the cerebellum. They lie deep within the white matter of each cerebellar hemisphere.

Cerebellar peduncles

The cerebellar peduncles are three paired bundles of white-matter fibers that connect the cerebellum to the brainstem. They serve as the major input and output pathways of the cerebellum.

Cerebellar tonsillar branch of posterior inferior cerebellar artery

The cerebellar tonsillar branch of the posterior inferior cerebellar artery (PICA) is a small artery that supplies the cerebellar tonsil, a portion of the inferior cerebellum. It is a branch of PICA, which itself arises from the vertebral artery.

Cerebellum

The cerebellum is a major brain structure located in the posterior cranial fossa, behind the brainstem. Its primary roles are coordination of movement, balance, posture, motor learning, and the timing/precision of voluntary actions. It also participates in cognitive and emotional processing.

Cerebral aqueduct

The cerebral aqueduct (also called the aqueduct of Sylvius or mesencephalic aqueduct) is a narrow channel within the midbrain that connects the third ventricle to the fourth ventricle, allowing cerebrospinal fluid (CSF) to flow between them.

Cerebral arterial circle (of Willis)

The Cerebral Arterial Circle (Circle of Willis) is a ring-like arterial anastomosis located at the base of the brain that provides collateral blood flow between the major arteries supplying the brain.

Cerebral artery

In anatomy, the term cerebral artery refers broadly to any artery that supplies blood to the brain. Usually, it refers to one of the major paired arteries (branches of the internal carotid and vertebrobasilar systems) that distribute oxygenated blood to the cerebral hemispheres.

Cerebral crus

The cerebral crus (plural: crura cerebri) refers to the large fiber bundles on the ventral (anterior) surface of the midbrain that carry descending motor pathways from the cerebral cortex to the brainstem and spinal cord.

Cerebral hemisphere

The cerebral hemispheres are the two large, paired halves of the cerebrum, forming the largest part of the human brain. They are responsible for higher cognitive functions, sensory perception, motor control, language, memory, and emotion.

Cerebral peduncle

The cerebral peduncle is a major structure of the midbrain that connects the cerebrum to the brainstem, serving as a highway for descending motor fibers and some ascending sensory fibers. It is composed of two parts: the cerebral crus (crura cerebri) anteriorly and the tegmentum posteriorly.

Cerebral vein (bridging vein)

The cerebral bridging veins are superficial veins of the brain that connect cortical veins on the surface of the cerebral hemispheres to the dural venous sinuses, traversing the subdural space. They are clinically important because they are thin-walled, valveless, and vulnerable to rupture, which can cause subdural hematomas.

Cerebrospinal fluid

Cerebrospinal fluid (CSF) is a clear, colorless body fluid that circulates within the ventricular system of the brain, the central canal of the spinal cord, and the subarachnoid space. It plays essential roles in protection, nutrition, and homeostasis of the central nervous system (CNS).

Cerebrum

The cerebrum is the largest part of the human brain, located in the anterior and superior portions of the cranial cavity. It is responsible for higher brain functions, including conscious thought, voluntary movement, sensory perception, language, memory, and emotion.

Cervical branch

The term “cervical branch” is an anatomical descriptor that usually refers to a branch of a nerve or artery supplying structures in the neck (cervical region). Its precise identity depends on the context (arterial, venous, or neural).

Cervical curvature

The cervical curvature refers to the natural inward (concave) curve of the cervical spine in the sagittal plane. It is one of the primary spinal curvatures that allow for flexibility, shock absorption, and balanced posture.

Cervical plexus

The cervical plexus is a network of nerve fibers in the neck formed by the ventral rami of the first four cervical spinal nerves (C1–C4). It supplies sensory, motor, and autonomic fibers to the neck, upper shoulder, and diaphragm.

Cervical spine

The cervical spine is the uppermost segment of the vertebral column, consisting of seven vertebrae (C1–C7) in the neck. It provides support for the head, mobility for neck movements, and protection for the spinal cord and vertebral arteries.

Cervical sympathetic trunk

The cervical sympathetic trunk is part of the autonomic nervous system, running along the neck lateral to the vertebral column, and is composed of sympathetic fibers and ganglia that supply head, neck, thoracic viscera, and some upper limb structures.

Cervical vertebra

A cervical vertebra is one of the seven vertebrae (C1–C7) of the cervical spine, forming the neck portion of the vertebral column. These vertebrae are specialized to provide support for the head, protection of the cervical spinal cord, and extensive mobility for the neck.

Cervicofacial division

The cervicofacial division refers to a division of the facial nerve (cranial nerve VII) after it exits the parotid gland, responsible for motor innervation to the lower face and neck muscles.

Cervicothoracic (stellate) ganglion

The cervicothoracic ganglion, also called the stellate ganglion, is a sympathetic ganglion formed by the fusion of the inferior cervical ganglion and the first thoracic (T1) ganglion. It is part of the cervical sympathetic trunk and is located in the lower neck/upper thoracic region, providing sympathetic innervation to the head, neck, upper limbs, and thoracic viscera.

Check ligament of lateral rectus muscle

The check ligament of the lateral rectus muscle (also called the lateral rectus–lateral orbital wall ligament) is a fibrous structure in the orbit that limits excessive abduction of the eyeball and stabilizes the lateral rectus muscle.

Check ligament of medial rectus muscle

The check ligament of the medial rectus muscle (also called the medial rectus–medial orbital wall ligament) is a fibrous band in the orbit that limits excessive adduction of the eyeball and stabilizes the medial rectus muscle.

Chiasmatic cistern

The chiasmatic cistern is a subarachnoid cistern in the brain that surrounds the optic chiasm. It is a CSF-filled space that serves as a pathway for cerebrospinal fluid (CSF) and important blood vessels) in the suprasellar region.

Choana

The choana (plural: choanae) is the posterior nasal aperture that forms the internal opening of the nasal cavity into the nasopharynx. It acts as the passageway for air from the nasal cavity into the pharynx, connecting the respiratory tract.

Chorda tympani nerve

The chorda tympani nerve is a branch of the facial nerve (cranial nerve VII) that carries special sensory (taste) fibers from the anterior two-thirds of the tongue and parasympathetic fibers to the submandibular and sublingual salivary glands.

Chorda tympani of facial nerve (VII) of petrotympanic fissure

The chorda tympani nerve is indeed a branch of the facial nerve (cranial nerve VII), and the petrotympanic fissure is the bony opening in the temporal bone through which it exits the middle ear to enter the infratemporal fossa.

Choroid

The choroid is a vascular layer of the eye located between the sclera and the retina. It plays a key role in supplying blood to the outer layers of the retina and in light absorption to improve visual clarity.

Choroid plexus

The choroid plexus is a network of specialized ependymal cells and blood vessels within the ventricular system of the brain that produces cerebrospinal fluid (CSF). It plays a central role in CSF secretion, composition, and circulation.

Choroid plexus of 3rd ventricle

The choroid plexus of the third ventricle is a specialized vascular structure within the roof of the third ventricle that produces cerebrospinal fluid (CSF). It is continuous with the lateral ventricle choroid plexus via the foramina of Monro.

Choroid plexus of 4th ventricle

The choroid plexus of the fourth ventricle is a vascular, CSF-secreting structure located within the roof of the fourth ventricle, continuous with the lateral recesses of the ventricle. It produces cerebrospinal fluid (CSF) and is an important landmark in neurosurgery.

Choroid plexus of lateral ventricle

The choroid plexus of the lateral ventricle is a highly vascular structure within the lateral ventricles of the brain that produces cerebrospinal fluid (CSF). It is continuous with the choroid plexus of the third ventricle via the foramen of Monro.

Choroidal branch to 4th ventricle

The choroidal branch to the fourth ventricle refers to the arterial supply to the choroid plexus of the fourth ventricle. These branches arise from nearby arteries and provide vascularization to the fourth ventricle’s choroid plexus, which produces cerebrospinal fluid (CSF).

Choroid plexus of 4th ventricle

The choroid plexus of the fourth ventricle is a highly vascularized structure within the roof and lateral recesses of the fourth ventricle that produces cerebrospinal fluid (CSF). It is part of the ventricular system and continuous with CSF pathways to the subarachnoid space.

Ciliary body

The ciliary body is a circular, muscular, and vascular structure in the eye located behind the iris. It is part of the uvea (middle layer of the eye) and plays a key role in aqueous humor production, accommodation, and lens stabilization.

Ciliary ganglion

The ciliary ganglion is a small parasympathetic ganglion located in the orbit that mediates autonomic control of the eye, specifically pupil constriction and lens accommodation.

Ciliary muscle

The ciliary muscle is a smooth muscle within the ciliary body of the eye that plays a central role in accommodation (focusing the lens for near vision) and helps regulate aqueous humor flow.

Ciliary part of retina

The ciliary part of the retina is the portion of the retina that lines the inner surface of the ciliary body. It is part of the non-visual (pars non-photosensitive) retina and is continuous anteriorly with the iris and ciliary body and posteriorly with the ora serrata, where it meets the visual retina.

Ciliary process

The ciliary processes are folded structures of the ciliary body in the eye that produce aqueous humor and serve as the attachment points for the suspensory ligaments (zonules) of the lens.

Cingular branches

The cingular branches generally refer to branches of cerebral arteries that supply the cingulate gyrus of the brain. The cingulate gyrus is part of the limbic lobe, located above the corpus callosum, and these branches provide its vascular supply.

Cingulate gyrus

The cingulate gyrus is a curved, cortical structure of the medial cerebral hemisphere that lies above the corpus callosum and is a major component of the limbic system, playing a key role in emotion, behavior, autonomic regulation, and cognition.

Cingulate sulcus

The cingulate sulcus is a prominent groove on the medial surface of the cerebral hemisphere that runs parallel and superior to the cingulate gyrus, separating it from the superior parts of the frontal and parietal lobes.

Circular esophageal muscle

The circular esophageal muscle is one of the two muscular layers of the esophagus that surrounds the lumen and is primarily responsible for propelling food toward the stomach via peristalsis.

Circular sulcus of insula (island of Reil)

The circular sulcus of the insula (also called the insula sulcus) is a prominent groove that surrounds the insular cortex (island of Reil) and separates it from the adjacent frontal, parietal, and temporal opercula.

Circumflex scapular artery

The circumflex scapular artery is a branch of the subscapular artery that supplies the posterior scapular region, including the scapular muscles and participates in the scapular anastomosis.

Cistern of corpus callosum

The cistern of the corpus callosum (also called the cistern of the lamina terminalis or sometimes referred to as the callosal cistern) is a subarachnoid cistern in the brain that lies around the anterior part of the corpus callosum, containing cerebrospinal fluid (CSF) and important blood vessels.

Claustrum

The claustrum is a thin, irregular sheet of gray matter located in the deep cerebral hemisphere, between the insular cortex and the putamen, and is thought to be involved in interhemispheric communication and integration of cortical information.

Clavicle

The clavicle, commonly known as the collarbone, is a long, S-shaped bone that serves as a strut connecting the upper limb to the axial skeleton. It plays a key role in shoulder mobility and stability.

Clavicular head of sternocleidomastoid muscle

The clavicular head of the sternocleidomastoid (SCM) muscle is one of the two heads of the SCM, the other being the sternal head. It is important for head and neck movements and acts as a key anatomical landmark in the neck.

Cleft

In anatomy, a cleft generally refers to a narrow fissure, groove, or split in a tissue, organ, or structure. It can be a normal anatomical feature or a congenital malformation depending on the context.

Cleft for internal capsule

The cleft for the internal capsule is an anatomical groove or space on the medial surface of the lentiform nucleus that accommodates the internal capsule, a major white matter structure carrying motor and sensory fibers between the cerebral cortex and subcortical structures.

Cleft formation

In anatomy and embryology, cleft formation refers to the developmental process in which grooves, fissures, or separations appear in tissues or organs, often as part of normal morphogenesis or, if incomplete, resulting in congenital malformations.

Clivus of occipital bone

The clivus is a sloping bony surface of the skull base formed by the occipital and sphenoid bones, located posterior to the dorsum sellae and anterior to the foramen magnum. It supports parts of the brainstem and is an important landmark in neurosurgery.

Clivus of sphenoid bone

The clivus of the sphenoid bone is the anterior part of the clivus, formed by the body of the sphenoid, which slopes posteriorly to join the clivus of the occipital bone at the spheno-occipital synchondrosis, forming a continuous bony surface supporting the brainstem.

Cochlear duct containing spiral organ (of Corti) of Cochlea

The cochlear duct, also called the scala media, is the endolymph-filled central duct of the cochlea in the inner ear. It contains the spiral organ (organ of Corti), which is the sensory organ for hearing.

Cochlea

The cochlea is the spiral-shaped, auditory portion of the inner ear responsible for converting sound vibrations into nerve impulses that the brain interprets as hearing.

Cochlear (spiral) ganglion

The cochlear (spiral) ganglion is the sensory ganglion of the cochlea, containing the cell bodies of bipolar neurons that transmit auditory information from the hair cells of the organ of Corti to the brainstem.

It is essential for hearing.

Cochlear aqueduct

The cochlear aqueduct is a narrow bony canal in the temporal bone that connects the perilymphatic space of the cochlea to the subarachnoid space around the brain.

Cochlear cupula

The cochlear cupula (also called the cupula cochleae) is the apex or tip of the bony cochlea. It is the central, highest, and innermost point of the cochlear spiral.

Cochlear duct (basal turn)

The cochlear duct (basal turn) refers to the first, lowest, and widest turn of the membranous cochlea as it spirals around the modiolus. This basal segment is especially important for hearing high-frequency sounds.

Cochlear nerve

The cochlear nerve is the auditory division of the vestibulocochlear nerve (cranial nerve VIII) and carries hearing information from the inner ear to the brain.

Cochlear nuclei

The cochlear nuclei are the first central auditory processing stations in the brainstem. They receive all incoming auditory information from the cochlear nerve (CN VIII) and begin detailed analysis of sound frequency, timing, and intensity.

Cochlear recess of vestibule

The cochlear recess of the vestibule (also called the recessus cochlearis) is a small indentation in the medial wall of the bony vestibule that forms the entrance to the cochlea.

Collateral eminence

The collateral eminence is an elongated ridge on the floor of the body of the lateral ventricle, produced by the underlying collateral sulcus of the temporal lobe.

Collateral sulcus

The collateral sulcus is a deep groove on the basal (inferior) surface of the temporal lobe of the brain. It plays a key role in forming the collateral eminence in the floor of the lateral ventricle.

Collateral trigone

The collateral trigone (also called the atrium of the lateral ventricle) is a triangular area of the lateral ventricle where the body, occipital horn, and temporal (inferior) horn meet.

Column of fornix

The column of the fornix is a bundle of white matter fibers in the brain that forms part of the fornix, the major output pathway of the hippocampus to subcortical structures such as the mammillary bodies.

Commissure of fornix

The commissure of the fornix (also called the hippocampal commissure) is a bundle of transverse fibers connecting the left and right fornical columns (or hippocampi), allowing interhemispheric communication between the two hippocampi.

Commissure of lips

The commissure of the lips (also called the oral commissure) is the corner or angle where the upper and lower lips meet on each side of the mouth.

Common bony and membranous limbs

In anatomical terminology, “common bony and membranous limbs” usually refers to structures that have both a bony (osseous) part and a membranous part forming a continuous anatomical feature. This term is most often used in ear and embryological anatomy, such as the ossicular chain of the middle ear or the cochlear and vestibular labyrinth.

Common carotid artery

The common carotid artery (CCA) is a major paired artery in the neck that supplies blood to the head and neck. It divides into the internal carotid artery (ICA) and external carotid artery (ECA).

Common carotid plexus

The common carotid plexus is a network of sympathetic nerve fibers that runs along the common carotid artery in the neck. It is part of the cervical sympathetic system and contributes to autonomic innervation of the head and neck.

Common facial vein

The common facial vein is a venous channel in the face that serves as a major connection between the facial vein and the internal jugular vein, providing an important pathway for venous drainage of the face.

Common membranous ampulla

The common membranous ampulla refers to a dilated portion of the membranous labyrinth in the inner ear, where the semicircular ducts open into the utricle. It is part of the vestibular system responsible for detecting angular acceleration.

Common tendinous ring

The common tendinous ring (also called the annulus of Zinn) is a fibrous ring in the orbit that serves as the origin for the four rectus muscles of the eye. It is an important anatomical landmark for the extraocular muscles and orbital nerves.

Common trunk for facial, retromandibular and lingual veins (common facial vein)

The “common trunk for facial, retromandibular, and lingual veins” refers to a venous convergence in the face and neck where these veins join to form or drain into the common facial vein.

This term is used to describe an anatomic variant or descriptive configuration of the common facial vein.

Common trunk receiving anterior branch of retromandibular vein

The common trunk receiving the anterior branch of the retromandibular vein refers to the venous channel that becomes the common facial vein after it receives the anterior branch of the retromandibular vein.

This is a standard and important venous configuration in the face and neck.

Common trunk receiving facial vein

The “common trunk receiving the facial vein” refers to the venous segment into which the facial vein drains before that trunk continues toward (or becomes) the internal jugular vein.

This structure depends on the local venous configuration, because the facial vein may join different partners.

Common trunk receiving facial, anterior branch of retromandibular, and lingual veins (common facial vein)

The common trunk receiving the facial vein, the anterior branch of the retromandibular vein, and the lingual vein refers to a triple-vein confluence that forms a large venous channel commonly identified as the common facial vein (or a variant of it).

This is an anatomical variant, but a well-recognized one.

Common trunk receiving lingual vein

The “common trunk receiving the lingual vein” refers to the venous channel that the lingual vein drains into before that trunk continues toward the internal jugular vein.

Communicating branch

A communicating branch is a nerve or vessel connection that links two larger structures to allow communication, meaning the passage of nerve impulses or blood flow between them.

Communicating branch of vagus nerve to carotid branch of glossopharyngeal nerve

The communicating branch of the vagus nerve to the carotid branch of the glossopharyngeal nerve is a small autonomic nerve connection found in the upper neck, within the carotid sheath region.

Communicating vein

A communicating vein is a general anatomical term describing any vein that connects one venous system or venous segment to another. It differs from a perforating vein, which specifically connects superficial to deep veins.

Communication between greater palatine and nasopalatine nerves at incisive canal

Communication between the greater palatine nerve and the nasopalatine nerve at the incisive canal refers to a small but consistent neural connection on the hard palate.

Communication to anterior jugular vein

Communication to the anterior jugular vein refers to one or more venous connections that link the anterior jugular vein with neighboring veins in the neck. This is a common feature of the superficial venous network.

Communication to auricular branch of vagus nerve

Communication to the auricular branch of the vagus nerve refers to a small neural connection from another cranial nerve or plexus that joins the auricular branch of the vagus nerve (Arnold’s nerve) as it travels toward the external ear.

Communication to brachial plexus

Communication to the brachial plexus refers to any nerve connection (communicating branch) that joins another nerve or plexus into the brachial plexus, supplementing its motor or sensory fibers.

Because the brachial plexus is a major neural hub, several small but important communicating branches join it from nearby cervical nerves, cranial nerves, and sympathetic fibers.

Communication to facial nerve

Communication to the facial nerve refers to any nerve branch from another cranial or peripheral nerve that joins the facial nerve (CN VII) or one of its branches. These communicating fibers help form mixed sensory, parasympathetic, and motor pathways around the face, ear, parotid region, and skull base.

Communication to opposite side

“Communication to opposite side” is an anatomical term used in neuroanatomy and vascular anatomy to describe a connection (nerve, vessel, or duct) that crosses the midline to join its contralateral counterpart.

It does not refer to one specific structure; it is a general descriptor applied in dissection guides, anatomical atlases, and radiologic landmarks.

Communication to vagus nerve

Communication to the vagus nerve refers to any nerve branch from another nerve or plexus that joins the vagus nerve (cranial nerve X) or one of its branches.

These communications usually provide sensory, parasympathetic, or sympathetic fibers.

Complete transverse cleft in intervertebral disc

A complete transverse cleft in an intervertebral disc refers to a horizontal splitting of the disc—usually through the annulus fibrosus and sometimes extending into the nucleus pulposus.

Concha of auricle

The concha of the auricle is the deep, bowl-shaped depression located just outside the external acoustic meatus (ear canal). It is the central hollow of the outer ear that helps funnel sound into the ear canal.

Condylar canal

The condylar canal (also called the condyloid canal) is a small bony canal located in the occipital bone, posterior and lateral to the occipital condyles.

Condylar emissary vein

The condylar emissary vein is a small venous channel that passes through the condylar canal of the occipital bone. It forms an important communication between intracranial and extracranial venous systems.

Condylar process

The condylar process (also called the condyloid process) is the posterior process of the mandible that participates in forming the temporomandibular joint (TMJ).

Condyle of mandible

The condyle of the mandible—also called the mandibular condyle—is the rounded articular head of the mandible that forms the movable portion of the temporomandibular joint (TMJ).

Condyle of occipital bone

The condyle of the occipital bone, also called the occipital condyle, is one of the two oval, convex articular processes on the inferior surface of the occipital bone. These structures form the primary joint between the skull and the vertebral column.

Cone of light

The cone of light (also called the light reflex or triangular cone of light) is a normal otoscopic finding seen when examining the tympanic membrane (eardrum).

Cones

In anatomy, cones generally refer to cone-shaped structures, but most commonly the term is used in neuroscience and vision to describe a specific type of retinal photoreceptor.

Confluence of sinuses

The confluence of sinuses (also called the torcular Herophili) is a dural venous sinus meeting point located at the internal occipital protuberance on the inner surface of the occipital bone.

Conjunctiva

The conjunctiva is a thin, transparent mucous membrane that lines the inner surface of the eyelids and covers the anterior surface of the sclera (but not the cornea).

Continuation of ophthalmic artery

The continuation of the ophthalmic artery is the supratrochlear artery (also called the frontal artery).

Contralateral olfactory bulb

Contralateral olfactory bulb refers to the olfactory bulb on the opposite side of the brain relative to a given structure, stimulus, or lesion.

Conus elasticus

The conus elasticus is a cone-shaped fibroelastic membrane in the larynx that forms the lateral and inferior walls of the laryngeal airway and contributes to the vocal ligament.

Cornea

The cornea is the transparent, avascular, anterior part of the fibrous layer of the eyeball. It forms the main refractive surface of the eye.

Corneoscleral junction (corneal limbus)

The corneoscleral junction, also called the corneal limbus, is the anatomical border where the transparent cornea meets the opaque sclera of the eye. It is a key transitional zone between these two structures.

Corniculate cartilage

The corniculate cartilage is a small, paired, conical elastic cartilage of the larynx that sits on the apex of each arytenoid cartilage.

Corniculate tubercle

The corniculate tubercle is an anatomical landmark in the larynx associated with the corniculate cartilage.

Coronal plane

The coronal plane is one of the standard anatomical planes used to describe the body in three dimensions.

Coronal suture

The coronal suture is a major fibrous joint (suture) of the skull that connects the frontal bone with the parietal bones.

Coronoid process of mandible

The coronoid process of the mandible is a thin, triangular, anterior projection of the ramus of the mandible, serving as an important attachment site for muscles involved in mastication.

Corpus callosum

The corpus callosum is the largest commissural fiber bundle in the brain, connecting the left and right cerebral hemispheres and allowing interhemispheric communication.

Corpus striatum

The corpus striatum is a major subcortical structure of the basal ganglia involved in motor control, procedural learning, and certain cognitive functions.

Corrugator super cilii

The corrugator supercilii is a small, narrow facial muscle located at the medial end of the eyebrow. It is primarily involved in drawing the eyebrows together and downward, producing vertical wrinkles over the glabella (“frowning”).

Cortex of lens

The cortex of the lens refers to the outer layer of the crystalline lens of the eye, surrounding the central nucleus.

Costal facets (for 1st rib)

The costal facets for the 1st rib are specific articular surfaces on the thoracic vertebrae where the head of the 1st rib articulates.

Costal lamella

The costal lamella is a thin plate of bone connecting the rib to the vertebra, forming part of the costovertebral articulation.

Costocervical trunk

The costocervical trunk is a short branch of the subclavian artery that supplies upper posterior thoracic wall and deep neck muscles.

Cranial base

The cranial base (or base of the skull) is the inferior part of the cranium that forms the floor of the cranial cavity and supports the brain. It differs from the cranial vault, which forms the rounded upper part of the skull.

Cranial nerve nuclei in brainstem

The cranial nerve nuclei in the brainstem are clusters of neurons where the cell bodies of cranial nerves reside. These nuclei are located in the midbrain, pons, and medulla, and each serves sensory, motor, or parasympathetic functions.

Cranial nerves

The cranial nerves are 12 pairs of nerves that emerge directly from the brain or brainstem, rather than from the spinal cord. They carry sensory, motor, or both types of information between the brain and structures of the head, neck, and some internal organs.

Cranial root of accessory nerve

The cranial root of the accessory nerve (part of cranial nerve XI) is one of the two roots that form the accessory nerve, the other being the spinal root. It is small, motor, and often considered functionally part of the vagus nerve (X).

Crest of sphenoid bone

The crest of the sphenoid bone refers to the ridge-like structures on the sphenoid that serve as attachment points for membranes or ligaments, or form boundaries between adjacent bones.

Cribriform plate

The cribriform plate is a horizontal part of the ethmoid bone that forms a portion of the anterior cranial fossa floor and allows passage of the olfactory nerves from the nasal cavity to the brain.

Cricoid attachment of longitudinal esophageal

The cricoid attachment of the longitudinal esophageal muscle refers to the uppermost (cervical) portion of the esophagus where its longitudinal muscle layer attaches to the cricoid cartilage of the larynx.

Cricoid cartilage

The cricoid cartilage is a ring-shaped cartilage of the larynx located just below the thyroid cartilage and above the trachea. It forms the complete cartilaginous ring of the airway, providing support and attachment points for muscles, ligaments, and the esophagus.

Cricopharyngeal muscle (part of inferior pharyngeal constrictor)

The cricopharyngeal muscle is the uppermost part of the esophagus and the inferior pharyngeal constrictor, forming the upper esophageal sphincter (UES). It plays a key role in swallowing and preventing regurgitation.

Cricopharyngeus muscle

The cricopharyngeus muscle is the main component of the upper esophageal sphincter (UES) and forms the posterior and lateral part of the inferior pharyngeal constrictor. It plays a critical role in swallowing and preventing reflux into the pharynx.

Cricothyroid artery

The cricothyroid artery is a small artery that supplies the larynx, particularly the cricothyroid region, and is important in laryngeal surgeries and emergency airway procedures.

Cricothyroid joint

The cricothyroid joint is a synovial joint between the cricoid and thyroid cartilages of the larynx. It plays a crucial role in tension and length adjustment of the vocal cords, which is essential for voice pitch modulation.

Cricothyroid ligament

The cricothyroid ligament is a fibrous structure connecting the cricoid and thyroid cartilages of the larynx. It is clinically important as the site for emergency airway access (cricothyrotomy).

Cricothyroid muscle

The cricothyroid muscle is an intrinsic muscle of the larynx that tenses and elongates the vocal cords, playing a key role in pitch modulation during phonation.

Crista galli

The crista galli is a vertical, midline bony ridge of the ethmoid bone that projects superiorly into the anterior cranial fossa. It serves as an attachment point for the falx cerebri, a dural fold that separates the two cerebral hemispheres.

Crown of tooth

The crown of a tooth is the visible part of the tooth that projects above the gum line (gingiva). It is primarily responsible for biting, cutting, or grinding food.

Cruciate ligament

The cruciate ligament refers to a ligament in the knee joint that stabilizes the femur and tibia. There are actually two cruciate ligaments: anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), forming a cross (X) within the knee joint, hence the name “cruciate.”

Crura of antihelix

The crura of the antihelix are part of the auricle (external ear) and form the Y-shaped ridge of the antihelix. They help give shape to the ear and support the conchal bowl.

Crus of fornix

The crus of the fornix is a posterior portion of the fornix, a C-shaped bundle of white matter fibers in the brain that connects the hippocampus to the mammillary bodies and other limbic structures.

Crux of helix

The crux of the helix is a prominent bend or point on the auricular helix of the external ear. It serves as a landmark separating different parts of the helix and contributes to the overall shape of the auricle.

Crypt

In anatomy, a crypt is a small tubular invagination or pit in the epithelial surface of an organ, often increasing surface area or providing a site for secretion, immune activity, or cell renewal.

Culmen of superior vermis

The culmen of the superior vermis is a prominent anterior portion of the superior (upper) part of the cerebellar vermis. It plays a role in coordination and posture as part of the cerebellum.

Culmen of vermis of cerebellum

The culmen of the vermis is a lobule of the anterior part of the superior vermis of the cerebellum. It is part of the midline cerebellar structure that connects the two cerebellar hemispheres and contributes to coordination of posture and movement.

Cuneate fasciculus

The cuneate fasciculus is a bundle of sensory nerve fibers in the dorsal (posterior) column of the spinal cord that carries fine touch, vibration, and proprioceptive information from the upper body (above T6) to the brain.

Cuneate tubercle

The cuneate tubercle is a small elevation on the dorsal surface of the medulla oblongata, formed by the underlying cuneate nucleus, which is part of the dorsal column–medial lemniscus system. It plays a key role in processing fine touch, vibration, and conscious proprioception from the upper body.

Cuneiform tubercle

The cuneiform tubercle is a small elevation on the lateral aspect of the vestibular area of the larynx, located in the aryepiglottic fold, overlying the cuneiform cartilage. It helps support the aryepiglottic fold and maintain the opening of the laryngeal inlet.

Cuneus

The cuneus is a wedge-shaped region of the occipital lobe of the brain, located superior to the calcarine sulcus. It is primarily involved in visual processing.

Cupula (dome) of pleura

The cupula (dome) of pleura, also called the cervical pleura, is the superior-most portion of the parietal pleura that extends into the root of the neck above the first rib.

Cutaneous branch of lacrimal nerve

The cutaneous branch of the lacrimal nerve is a small sensory branch that supplies the lateral part of the upper eyelid and adjacent skin of the temple region. It is part of the ophthalmic division (V₁) of the trigeminal nerve (CN V).

Cutaneous nerves of head and neck

The cutaneous nerves of the head and neck are responsible for sensory innervation of the skin in these regions. They arise mainly from cranial nerves (especially the trigeminal nerve, CN V) and the cervical plexus (C2–C4).

Declive of superior vermis

The declive is a lobule of the superior vermis of the cerebellum, located posterior to the culmen. It is part of the posterior superior vermis and contributes to coordination and balance.

Declive of vermis of cerebellum

The declive of the vermis is a lobule of the posterior part of the superior vermis of the cerebellum, situated posterior to the culmen. It is involved in coordination of posture and movement.

Decussation of pyramids

The decussation of pyramids is the point where most of the motor fibers from the cerebral cortex cross from one side to the opposite side. These fibers are primarily part of the corticospinal tract, specifically the lateral corticospinal tract.

Decussation of superior cerebellar peduncle

The decussation of the superior cerebellar peduncle is another crucial crossing point in the brainstem, but it’s involved in cerebellar output, not corticospinal motor fibers.

Deep auricular artery

The deep auricular artery is a small but important branch of the maxillary artery, primarily supplying the ear and surrounding structures.

Deep branch of transverse cervical artery (dorsal scapular artery)

The deep branch of the transverse cervical artery, more commonly called the dorsal scapular artery, is an important vessel supplying muscles of the posterior scapular region.

Deep cervical artery

The deep cervical artery is a branch of the costocervical trunk (from the subclavian artery) that supplies the deep muscles of the posterior neck.

Deep cervical muscles

The deep cervical muscles are a group of muscles located posterior and lateral to the cervical vertebrae, lying deep to the trapezius, splenius, and other superficial muscles of the neck. They are mainly responsible for posture, head and neck movement, and stabilization of the cervical spine.

Deep cervical vein

The deep cervical vein is a vein of the posterior neck that runs alongside the deep cervical artery, draining the deep muscles and posterior structures of the neck.

Deep facial vein

The deep facial vein (also called the posterior facial vein) is an important vein of the face that connects the facial venous system to the pterygoid venous plexus. It is clinically significant because it forms part of the “danger triangle of the face” venous connections, which can allow infections to spread from the face to the cavernous sinus.

Deep lateral cervical (internal jugular) nodes

The deep lateral cervical lymph nodes, also called the internal jugular lymph nodes, are a group of deep cervical lymph nodes that lie along the internal jugular vein. They are clinically important because they are the primary lymphatic drainage nodes for the head and neck.

Deep layer of temporal fascia

The deep layer of the temporal fascia is an important anatomical structure over the temporal region of the skull, providing support for muscles and forming part of the temporo-parietal fascial layers.

Deep lingual artery

The deep lingual artery is a branch of the lingual artery that supplies the anterior part of the tongue.

Deep lingual nerve

The deep lingual nerve is the terminal portion of the lingual nerve, which is itself a branch of the mandibular nerve (V3, the third division of the trigeminal nerve). It provides sensory innervation to the anterior tongue.

Deep lingual veins

The deep lingual veins are the primary veins draining the anterior part of the tongue, running on its ventral (underside) surface. They are clinically important because they are readily visible through the mucosa and used for sublingual drug administration.

Deep middle cerebral vein

The deep middle cerebral vein (also called the deep Sylvian vein) is one of the deep veins of the brain, specifically associated with the lateral (Sylvian) fissure. It plays an important role in draining the deep structures of the cerebral hemisphere.

Deep part of masseter muscle

The deep part of the masseter muscle is the smaller, deeper, and more vertically oriented portion of the masseter, one of the primary muscles of mastication.

Deep petrosal nerve

The deep petrosal nerve is a postganglionic sympathetic nerve that carries sympathetic fibers from the superior cervical ganglion to the pterygopalatine fossa and eventually to the mucosa and vasculature of the nasal cavity, palate, and lacrimal gland region. It joins the greater petrosal nerve to form the nerve of the pterygoid canal (Vidian nerve).

Deep superficial cerebral veins

The term “deep superficial cerebral veins” refers to a group of veins that bridge the superficial and deep venous drainage systems of the brain. They are not purely superficial or purely deep, but occupy the deep portions of the superficial venous network, especially around the Sylvian fissure.

These veins include major channels that collect blood from deep cortical and subcortical regions and drain toward the superficial middle cerebral vein or the basal vein system.

Deep temporal arteries

The deep temporal arteries are two major arteries—anterior and posterior—that supply the temporalis muscle and parts of the temporal fossa. They are important branches of the maxillary artery and play key roles in mastication anatomy.

Deep temporal nerves

The deep temporal nerves are motor branches of the mandibular nerve (CN V3) that supply the temporalis muscle. They run with the deep temporal arteries in the temporal fossa.

Deep temporal veins

The deep temporal veins are paired venous channels—anterior and posterior—that drain the temporalis muscle and communicate between the superficial temporal venous system and the pterygoid venous plexus. They closely accompany the deep temporal arteries.

Deep veins of brain

The deep veins of the brain are the major venous channels that drain the deep internal structures—including the deep white matter, basal ganglia, diencephalon, and parts of the ventricular system. They ultimately converge into the great cerebral vein (of Galen) and then the straight sinus

Deeper (accessory) part of tectorial membrane

The deeper (accessory) part of the tectorial membrane is a thin, deep lamina of the tectorial membrane located at the craniovertebral junction. It is anatomically distinct from—but closely associated with—the stronger superficial part of the tectorial membrane.

Deformed vertebral bodies

Deformed vertebral bodies refers to any abnormal shape, height, contour, or alignment of one or more vertebrae. This is a descriptive term, not a specific diagnosis. Deformation can occur from congenital, developmental, traumatic, infectious, metabolic, or neoplastic causes.

Deltoid fascia

The deltoid fascia is the deep fascia covering the deltoid muscle. It plays an important role in compartmentalization of the shoulder region, muscle support, and surgical anatomy.

Deltoid muscle

The deltoid muscle is the large, triangular muscle covering the shoulder joint, responsible for most movements of the arm at the shoulder. It is a key landmark in both anatomy and clinical practice.

Dens

The dens, also known as the odontoid process, is a bony projection of the axis (C2 vertebra) that forms the pivot around which the atlas (C1) rotates, enabling the head to turn from side to side. It is a key structure in cervical spine anatomy and stability.

Dens superior articular facet for atlas

The superior articular facet of the dens is a small, smooth surface on the tip of the odontoid process (dens) of C2 (axis) that articulates with the anterior arch of the atlas (C1). This facet is part of the atlanto-odontoid articulation, allowing controlled rotation of the head.

Dental and gingival branches

The dental and gingival branches are branches of the trigeminal nerve (CN V), specifically from its maxillary (V2) and mandibular (V3) divisions, which supply the teeth, their supporting structures, and the surrounding gingiva. They include both sensory nerves and accompanying blood vessels.

Dental pulp containing vessels and nerves

The dental pulp is the soft connective tissue inside the tooth that contains blood vessels, lymphatics, and nerves, providing nutrition, sensation, and defense for the tooth.

Dentate cerebellar nuclei

The dentate cerebellar nuclei are the largest and most lateral of the deep cerebellar nuclei. They are crucial relay stations in the cerebellar circuitry, involved in planning and coordination of voluntary movements.

Dentate gyrus

The dentate gyrus is a key part of the hippocampal formation in the medial temporal lobe, playing a crucial role in memory formation, learning, and neurogenesis.

Dentate nucleus of cerebellum

The dentate nucleus of the cerebellum is the largest and most lateral of the deep cerebellar nuclei, embedded in the white matter of the lateral cerebellar hemisphere. It plays a key role in planning, initiation, and coordination of voluntary movements, especially fine motor control.

Dentine and dentinal tubules

The dentine (or dentin) is the calcified tissue forming the bulk of a tooth, lying beneath enamel and cementum, and surrounding the pulp cavity. It contains dentinal tubules, which are microscopic channels critical for sensation, nutrition, and dentin repair.

Depressor anguli oris

The depressor anguli oris is a facial muscle involved in frowning, responsible for pulling down the corners of the mouth. It is a key muscle of facial expression.

Depressor labii inferioris

The depressor labii inferioris is a facial muscle that depresses the lower lip, contributing to expressions such as sadness or doubt. It lies in the lower face and works in coordination with other perioral muscles.

Depressor septi nasi

The depressor septi nasi is a small facial muscle that acts on the nasal septum and nostrils, helping in nasal movements during facial expression.

Descending aorta

The descending aorta is the part of the aorta that continues from the aortic arch and runs down through the thorax and abdomen, supplying most of the thoracic and abdominal organs.

Descending branch of occipital artery

The descending branch of the occipital artery is a branch of the occipital artery (itself a branch of the external carotid artery) that descends in the posterior neck to contribute to the posterior cervical blood supply.

Descending palatine artery

The descending palatine artery is a branch of the maxillary artery (a terminal branch of the external carotid artery) that supplies the palate and adjacent structures.

Descending palatine nerves

The descending palatine nerves are branches of the maxillary nerve (CN V2) that descend through the palatine canal to supply the palate, gingiva, and tonsils. They travel together with the descending palatine artery.

Digastric fossa

The digastric fossa is an anatomical landmark on the mandible that serves as the origin site for the anterior belly of the digastric muscle.

Digastric muscle (posterior belly)

The posterior belly of the digastric muscle is one of the two bellies of the digastric muscle, a suprahyoid muscle that helps in depressing the mandible and elevating the hyoid during swallowing and speech.

Digastric muscle

The digastric muscle is a suprahyoid muscle with two bellies (anterior and posterior) connected by an intermediate tendon. It plays a key role in depressing the mandible, elevating the hyoid bone, and stabilizing the floor of the mouth.

Digastric muscle (anterior belly)

The anterior belly of the digastric muscle is one part of the digastric muscle, a suprahyoid muscle that assists in depressing the mandible and elevating the hyoid bone.

Dilator pupillae muscle

The dilator pupillae muscle is a radially arranged smooth muscle of the iris that dilates the pupil, controlling the amount of light entering the eye. It is part of the autonomic control of the eye.

Diploe

The diploë is a specialized anatomical feature of the flat bones of the skull, particularly the cranial vault. It is the spongy, cancellous bone layer sandwiched between the outer and inner cortical tables of the skull.

Diploic vein

The diploic veins are valveless veins located within the diploë of the cranial bones that play a role in venous drainage of the skull and communication with intracranial venous sinuses.

Distal medial striate artery

The distal medial striate artery is a branch of the anterior cerebral artery (ACA) that supplies parts of the basal ganglia and internal capsule. It is part of the medial striate artery system (recurrent artery of Heubner).

Dorsal branch to corpus callosum

The dorsal branch to the corpus callosum is a branch of the anterior cerebral artery (ACA) that supplies parts of the corpus callosum, particularly its dorsal (superior) aspect.

Dorsal lateral geniculate nucleus

The dorsal lateral geniculate nucleus (dLGN) is a thalamic relay nucleus that plays a key role in visual processing, transmitting signals from the retina to the primary visual cortex (V1).

Dorsal lingual artery and vein

The dorsal lingual artery and vein are the main vascular structures supplying and draining the dorsum of the tongue, particularly its posterior and middle parts.

Dorsal lingual vein coursing medial to hyoglossus muscle

The dorsal lingual vein is a venous structure that drains the dorsum of the tongue, and its course medial to the hyoglossus muscle is clinically and anatomically significant.

Dorsal longitudinal fasciculus

The dorsal longitudinal fasciculus (DLF) is a longitudinal bundle of fibers in the brainstem that plays a key role in autonomic and visceral regulation by connecting the hypothalamus, brainstem, and spinal autonomic centers.

Dorsal median sulcus

The dorsal median sulcus is a key anatomical feature of the spinal cord, marking its midline on the posterior (dorsal) surface.

Dorsal nasal artery

The dorsal nasal artery is a terminal branch of the ophthalmic artery that supplies the nose and surrounding structures.

Dorsal nasal vein

The dorsal nasal vein is a venous structure that drains blood from the bridge and dorsum of the nose and communicates with both facial and ophthalmic venous systems.

Dorsal rami of cervical spinal nerves

The dorsal rami of the cervical spinal nerves are branches of the cervical spinal nerves that primarily innervate the deep muscles and skin of the posterior neck and scalp.

Dorsal root

The dorsal root is a key component of a spinal nerve that carries sensory (afferent) information from the periphery into the spinal cord.

Dorsal scapular artery

The dorsal scapular artery is an artery that primarily supplies the medial border of the scapula and adjacent muscles of the back. It is an important vessel in the posterior shoulder and scapular region.

Dorsal vagal nucleus

The dorsal vagal nucleus (DVN) is a cranial nerve nucleus in the medulla oblongata that is a major source of parasympathetic output via the vagus nerve (cranial nerve X). It plays a key role in autonomic control of thoracic and abdominal organs.

Dorsal vein of corpus callosum

The dorsal vein of the corpus callosum is one of the superficial cerebral veins that drains blood from the corpus callosum and adjacent medial cerebral cortex into the deep venous system.

Dorsomedial nuclei of hypothalamus

The dorsomedial nucleus (DMN) of the hypothalamus is a key hypothalamic nucleus involved in autonomic regulation, feeding, circadian rhythms, and emotional behavior.

Dorsum of tongue

The dorsum of the tongue refers to the upper (superior) surface of the tongue, which is highly specialized for taste, sensation, and mechanical functions in speech, mastication, and swallowing.

Dorsum sellae of sella turcica of sphenoid bone

The dorsum sellae is a bony landmark of the sphenoid bone, forming part of the sella turcica, which houses the pituitary gland.

Duct of gland

The term “duct of a gland” refers to a tubular structure that conveys secretions from a gland to its target site, whether that be the surface of an epithelium, a body cavity, or another organ.

Ductus reuniens

The ductus reuniens is a small but important structure in the inner ear, connecting the cochlear duct (scala media) of the cochlea with the saccule of the vestibular system.

Duodenum

The duodenum is the first part of the small intestine, connecting the stomach to the jejunum. It plays a critical role in digestion and absorption by mixing chyme with bile and pancreatic secretions.

Dura mater

The dura mater is the tough, outermost layer of the meninges that surrounds and protects the brain and spinal cord. It consists of two layers - the periosteal layer and the meningeal layer, and it provides structural support, protection, and venous drainage pathways.

Dura-skull interface (site of epidural hematoma)

The dura-skull interface is the anatomical plane between the periosteal layer of cranial dura mater and the inner table of the cranial bones, and it is the classic site for epidural (extradural) hematomas.

Dural venous sinuses

The dural venous sinuses are endothelial-lined channels located between the periosteal and meningeal layers of the cranial dura mater that drain venous blood from the brain, skull, and meninges into the internal jugular veins. They are key components of cerebral venous circulation.

Efferent fiber

An efferent fiber is a nerve fiber that carries impulses away from the central nervous system (CNS) to the periphery, typically to muscles or glands, to produce a response.

Efferent fibers to olfactory bulb

The efferent fibers to the olfactory bulb are less commonly discussed than afferent fibers from the olfactory epithelium, but they exist as part of centrifugal fibers that modulate olfactory processing.

Efferent hypophyseal vein to cavernous sinus

The efferent hypophyseal veins are the venous channels that drain blood from the pituitary gland (hypophysis) into the cavernous sinus.

Efferent hypophyseal veins

The efferent hypophyseal veins are the venous channels that drain blood from the pituitary gland (hypophysis) into the systemic venous system, primarily the cavernous sinus.

Elliptical recess of vestibule

The elliptical recess (recessus ellipticus) of the vestibule is a small anatomical feature of the inner ear, specifically part of the vestibular system, which contributes to the sense of balance.

Emboliform cerebellar nuclei

The emboliform nucleus is one of the deep cerebellar nuclei located within the cerebellum and plays a key role in motor coordination.

Emissary vein

An emissary vein is a venous channel that connects the extracranial venous system with the intracranial dural venous sinuses, passing through foramina in the skull. These veins are clinically important because they provide a potential route for infection from the face to the cranial cavity.

Enamel

Enamel is the hard, outermost layer of the tooth, providing protection against mechanical forces and chemical damage. It is the hardest tissue in the human body.

Endolymphatic duct

The endolymphatic duct is a small but crucial structure of the inner ear, forming part of the endolymphatic system that helps regulate endolymph volume and pressure.

Endolymphatic duct in vestibular aqueduct

The endolymphatic duct within the vestibular aqueduct is a key structure of the inner ear that connects the vestibule (utricle and saccule) to the endolymphatic sac, running through the osseous vestibular aqueduct.

Endolymphatic duct of external opening of vestibular aqueduct

The external opening of the vestibular aqueduct marks the terminus of the endolymphatic duct on the posterior surface of the petrous temporal bone, where it communicates with the endolymphatic sac.

Endolymphatic sac

The endolymphatic sac is a key component of the endolymphatic system of the inner ear, involved in regulating endolymph volume, pressure, and ionic composition.

Endothelium of anterior chamber

The endothelium of the anterior chamber refers to the innermost cellular layer lining the inner surface of the cornea, which faces the anterior chamber of the eye. This layer plays a critical role in maintaining corneal transparency and regulating aqueous humor balance.

Ependyma

Ependyma is the epithelial lining of the ventricular system of the brain and central canal of the spinal cord, playing a key role in cerebrospinal fluid (CSF) circulation and homeostasis.

Epicranial aponeurosis of scalp

The epicranial aponeurosis (also called the galea aponeurotica) is a tendinous sheet on the scalp that connects the frontal and occipital muscles of the scalp, forming part of the scalp’s layered anatomy.

Epidural fat and anterior internal vertebral (epidural) venous plexus

The epidural fat and anterior internal vertebral (epidural) venous plexus are important structures within the vertebral canal, lying in the epidural space. They cushion the spinal cord and provide venous drainage.

Epidural hematoma

An epidural hematoma (EDH) is a bleeding between the inner surface of the skull and the dura mater, usually due to trauma. It’s a neurosurgical emergency because it can rapidly compress the brain.

Epiglottis

The epiglottis is a leaf-shaped cartilage of the larynx that plays a critical role in protecting the airway during swallowing.

Episcleral artery and vein

The episcleral arteries and veins are vascular structures of the outer layer of the eyeball, specifically the episclera, which lies between the conjunctiva and sclera. They play a key role in ocular blood supply and aqueous humor drainage.

Episcleral space

The episcleral space is the potential space in the outer layer of the eyeball, between the sclera and the episclera, and it plays an important role in ocular circulation and aqueous humor outflow.

Episcleral vein

The episcleral veins are veins located in the episclera, the thin vascular layer on the outer surface of the sclera, playing a crucial role in aqueous humor drainage and ocular venous circulation.

Epitympanic recess

The epitympanic recess (also called the attic of the middle ear) is an important part of the middle ear cavity, located superior to the tympanic membrane. It houses key structures of the ossicular chain and communicates with the mastoid air cells.

Equator of lens

The equator of the lens is an anatomical landmark of the eye’s crystalline lens that separates its anterior and posterior surfaces and serves as the site of zonular fiber attachment.

Equatorial zonular fibers

The equatorial zonular fibers are part of the suspensory apparatus of the lens and are essential for lens positioning and accommodation.

Esophageal muscles

The esophageal muscles are organized into distinct layers that vary along the length of the esophagus, enabling peristalsis and coordinated swallowing.

Esophageal plexus

The esophageal plexus is a network of autonomic nerves surrounding the esophagus, providing sympathetic and parasympathetic innervation to the esophagus and nearby structures.

Esophagus

The esophagus is a muscular tube that conveys food and liquids from the pharynx to the stomach, playing a central role in swallowing and gastrointestinal motility.

Ethmoid air cells (sinuses)

The ethmoid air cells (or ethmoid sinuses) are a group of small, air-filled cavities within the ethmoid bone that form part of the paranasal sinus system. They are important for lightening the skull, humidifying inhaled air, and draining into the nasal cavity.

Ethmoid bone

The ethmoid bone is a complex, delicate cranial bone located at the roof of the nasal cavity, contributing to the nasal septum, medial orbital walls, and anterior cranial fossa. It is centrally located and plays key roles in olfaction, airflow, and sinus anatomy.

Ethmoid sinus

The ethmoid sinus (or ethmoid air cells) is a collection of small air-filled cavities within the ethmoid bone, forming part of the paranasal sinus system. They are important for lightening the skull, humidifying air, and facilitating nasal airflow.

Ethmoidal air cells

The ethmoidal air cells (also called ethmoid sinuses) are a group of small, air-filled cavities within the ethmoid bone, part of the paranasal sinus system. They are essential for lightening the skull, humidifying inhaled air, and facilitating sinus drainage.

Ethmoidal bulla

The ethmoidal bulla is a prominent structure within the middle meatus of the nasal cavity, formed by middle ethmoidal air cells. It serves as an important landmark in sinus anatomy and endoscopic sinus surgery.

Ethmoidal cell

The ethmoidal cell is an individual air-filled cavity within the ethmoid bone, also known as an ethmoid sinus. Collectively, these cells form the ethmoid air cell system, which is part of the paranasal sinus system.

Ethmoidal process of inferior nasal concha

The ethmoidal process of the inferior nasal concha is a bony projection that articulates with the ethmoid bone, forming part of the lateral nasal wall.

Excretory ducts of lacrimal gland

The excretory ducts of the lacrimal gland are small channels that transport tears produced by the lacrimal gland into the conjunctival sac, allowing tears to spread over the ocular surface.

External acoustic meatus

The external acoustic meatus (also called the external auditory canal) is the bony and cartilaginous passage leading from the auricle to the tympanic membrane. It conducts sound waves to the middle ear.

External branch of anterior ethmoidal artery

The external branch of the anterior ethmoidal artery is a small arterial branch that contributes to the vascular supply of the external nose and surrounding structures.

External branch of superior laryngeal nerve

The external branch of the superior laryngeal nerve (SLN) is a motor nerve branch of the vagus nerve (cranial nerve X) that innervates a key laryngeal muscle involved in voice modulation.

External capsule

The external capsule is a white matter structure in the brain that serves as a pathway for association and projection fibers, lying between major basal ganglia structures.

External carotid plexus

The external carotid plexus is a network of sympathetic nerve fibers that accompanies the external carotid artery and its branches, providing sympathetic innervation to structures of the face and neck.

External carotid artery

The external carotid artery (ECA) is a major artery of the head and neck that supplies most of the structures of the face, oral cavity, pharynx, and scalp, excluding the brain and orbit (which are supplied by the internal carotid artery).

External carotid plexus

The external carotid plexus is a network of sympathetic nerve fibers that accompanies the external carotid artery and its branches, supplying sympathetic innervation to structures of the face, neck, and superficial head.

External craniocervical ligaments

The external craniocervical ligaments are a group of extrinsic ligaments connecting the skull (cranium) to the cervical spine, providing stability, limiting excessive movement, and protecting neural structures.

External ear

The external ear (also called the auricle or pinna plus external auditory canal) is the outer portion of the ear, responsible for collecting and directing sound waves to the tympanic membrane.

External eye muscles

The external eye muscles (also called extraocular muscles) are the skeletal muscles that control eye movements and maintain eye position, allowing precise coordination of vision.

External jugular vein

The external jugular vein (EJV) is a superficial vein of the neck that drains blood from the scalp and face into the subclavian vein.

External medullary lamina

The external medullary lamina is a layer of white matter in the thalamus that separates specific thalamic nuclei and serves as a key anatomical landmark.

External nasal artery and nerve

The external nasal artery and nerve are key structures supplying the external nose, providing blood supply and sensory innervation.

External nasal branches of anterior ethmoidal nerve of ophthalmic nerve

The external nasal branches of the anterior ethmoidal nerve are cutaneous sensory branches that supply the skin of the lower and lateral parts of the nose.

External nasal vein

The external nasal vein is a superficial vein of the nose that primarily drains the dorsum and tip of the external nose and communicates with deeper venous structures.

External occipital crest

The external occipital crest is a bony ridge on the occipital bone of the skull that serves as an important attachment site for ligaments and muscles of the posterior neck.

External occipital crest of occipital bone

The external occipital crest of the occipital bone is a midline bony ridge on the posterior aspect of the occipital bone, serving as a key attachment site for the nuchal ligament and posterior neck muscles.

External occipital protuberance

The external occipital protuberance (EOP) is a prominent bony landmark on the posterior aspect of the occipital bone that serves as an attachment point for ligaments and muscles of the neck.

External opening of vestibular aqueduct

The external opening of the vestibular aqueduct is a key anatomical landmark of the inner ear, marking the exit of the endolymphatic duct onto the posterior surface of the temporal bone.

External palatine vein

The external palatine vein is a venous structure of the palate that contributes to venous drainage of the soft palate and communicates with deeper venous systems.

External sheath of optic nerve (dura mater)

The external sheath of the optic nerve refers to the dural covering of the optic nerve, which is continuous with the cranial meninges.

Extraocular muscles

The extraocular muscles (EOMs) are the six muscles that control the movement of the eyeball and maintain its position within the orbit.

Extrinsic eye muscles

The extrinsic eye muscles are the same as the extraocular muscles—the six muscles that control the movement of the eyeball and stabilize it within the orbit. “Extrinsic” emphasizes that these muscles originate outside the eyeball (in the orbit) and insert onto the sclera, in contrast to intrinsic eye muscles like the ciliary muscle or iris muscles.

Eye

The eye (or globe) is the sensory organ of vision, responsible for detecting light, forming images, and transmitting visual information to the brain via the optic nerve.

Eye (vitreous chamber)

The vitreous chamber is the largest internal space of the eyeball, filled with the vitreous body, and plays a critical role in maintaining eye shape and transmitting light to the retina.

Eyeball

The eyeball (or globe of the eye) is the spherical organ responsible for vision, located in the orbit. It contains specialized structures for detecting light, focusing images, and transmitting visual information to the brain.

Eyelashes (cilia)

Eyelashes (cilia) are specialized hairs located along the margins of the eyelids that play an important role in protecting the eyes.

Eyelids

The eyelids are movable folds of skin and muscle that cover and protect the anterior surface of the eyeball. They are essential for protection, lubrication, and regulation of light entering the eye.

Face sinuses

The paranasal sinuses (often called facial sinuses) are air-filled cavities within the bones of the face and skull that connect to the nasal cavity. They play roles in lightening the skull, humidifying air, enhancing voice resonance, and protecting structures during trauma.

Facet

In anatomy, a facet refers to a small, smooth, flat surface on a bone, typically where it articulates (forms a joint) with another bone.

Facet (zygapophyseal) joint between C2 and C3

The facet (zygapophyseal) joint between C2 and C3 is a synovial joint between the articular processes of the second cervical vertebra (axis) and the third cervical vertebra (C3).

Facet joint

A facet joint (also called a zygapophyseal joint) is a synovial joint between the articular processes of two adjacent vertebrae. These joints are crucial for spinal stability and controlled movement.

Facial artery

The facial artery is a major branch of the external carotid artery that supplies most of the structures of the face.

Facial plexus

The facial plexus is a network of nerves that provides motor innervation to the muscles of facial expression and has connections to sensory and autonomic fibers.

Facial vein

The facial vein is a major superficial vein of the face that drains blood from the face into the internal jugular vein, forming important connections with intracranial venous structures.

Facial canal

The facial canal is a bony passage within the temporal bone that transmits the facial nerve (CN VII) and its branches. It is clinically important because lesions here can cause facial nerve palsy.

Facial colliculus

The facial colliculus is an important structure in the dorsal part of the pons within the floor of the fourth ventricle, notable for its role in cranial nerve function.

Facial muscles

The facial muscles are a group of skeletal muscles responsible for facial expression, as well as assisting in speech, mastication, and eye protection. They are primarily innervated by the facial nerve (cranial nerve VII).

Facial nerve

The facial nerve (cranial nerve VII) is a mixed cranial nerve that carries motor, sensory, and parasympathetic fibers, primarily responsible for facial expression, taste, and glandular function.

Facial nerve (VII) in stylomastoid foramen

The facial nerve (cranial nerve VII) in the stylomastoid foramen represents its exit point from the temporal bone to the face, after traversing the facial canal. This is a key anatomical landmark for understanding facial nerve function and surgical relevance.

Facial nerve (VII) of internal acoustic meatus

The facial nerve (cranial nerve VII) in the internal acoustic meatus represents its entry point into the temporal bone and its initial intracranial course. This segment is important for understanding facial nerve anatomy and pathologies affecting the temporal bone or cerebellopontine angle.

Facial nerve and geniculate ganglion

The facial nerve (cranial nerve VII) and geniculate ganglion are key structures in the temporal bone, critical for facial expression, taste, and parasympathetic functions.

Facial nerve branches and parotid gland

The facial nerve (cranial nerve VII) branches and parotid gland are intimately related anatomically because the facial nerve emerges from the stylomastoid foramen and passes through the parotid gland, forming a plexus of terminal branches that innervate the muscles of facial expression.

Facial nodes

The facial lymph nodes are a group of superficial and deep lymph nodes along the course of the facial vein that drain lymph from the superficial structures of the face into the deep cervical lymph nodes. They are clinically important in facial infections and cancer metastasis.

Facial nucleus

The facial nucleus is the motor nucleus of the facial nerve (cranial nerve VII), located in the pons, and is responsible for innervating the muscles of facial expression.

Facial artery

The facial artery is the main artery supplying the superficial face, arising from the external carotid artery. It provides oxygenated blood to the facial structures, lips, nose, and muscles of facial expression.

Facial vein

The facial vein is the main superficial vein of the face, draining blood from the anterior face and orbit into the internal jugular vein. It has important clinical significance due to its connections with deep venous structures.

Falx cerebelli

The falx cerebelli is a small, sickle-shaped fold of dura mater located in the posterior cranial fossa that partially separates the two cerebellar hemispheres.

Falx cerebri

The falx cerebri is a major fold of the dura mater that separates the two cerebral hemispheres in the longitudinal fissure. It is one of the most important dural partitions in the cranial cavity.

Fascia of infrahyoid muscles

The fascia of the infrahyoid muscles (also called the pretracheal fascia) is a layer of deep cervical fascia that encloses the infrahyoid (strap) muscles and related structures in the anterior neck. It is important for compartmentalization, surgical approaches, and spread of infections.

Fascia of orbit and eyeball

The fascia of the orbit and eyeball refers to the connective tissue layers that support, protect, and compartmentalize the globe (eyeball) and orbital contents. These layers include the orbital fascia (periorbita), Tenon’s capsule, and related connective tissue structures.

Fascial sheath of eyeball

The fascial sheath of the eyeball, also known as Tenon’s capsule (fascia bulbi), is a thin connective tissue layer that envelops the globe, separating it from orbital fat and providing a smooth interface for eye movements.

Fastigial cerebellar nuclei

The fastigial nucleus is one of the deep cerebellar nuclei, located in the vermal region of the cerebellum, and plays a key role in balance, posture, and coordination of axial muscles.

Fat in orbit

Orbital fat is the adipose tissue within the orbit that cushions, supports, and facilitates the movement of the eyeball and orbital structures. It is an important structural and functional component of the orbit.

Fat in posterior triangle

The fat in the posterior triangle of the neck is part of the loose connective tissue and adipose tissue that occupies the space between muscles and fascial layers. It provides protection, cushioning, and a medium for neurovascular structures to pass.

Fibers from contralateral olfactory bulb

The fibers from the contralateral olfactory bulb refer to the commissural connections in the olfactory system that allow inter-hemispheric communication of olfactory information. These are mainly mediated by the anterior commissure.

Fibers to contralateral olfactory bulb

The fibers to the contralateral olfactory bulb are part of the interhemispheric olfactory pathway, allowing communication between the two olfactory bulbs via the anterior commissure. These fibers primarily originate from the anterior olfactory nucleus.

Fibers to pharyngoepiglottic fold

The fibers to the pharyngoepiglottic fold are motor and sensory nerve fibers that innervate this fold, which forms part of the laryngeal inlet and is important in swallowing and airway protection.

Fibrous capsule of thyroid gland

The fibrous capsule of the thyroid gland is a layer of connective tissue that envelops the thyroid gland, providing structural support and compartmentalization.

Fibrous loop for intermediate digastric tendon

The fibrous loop for the intermediate tendon of the digastric muscle is a fibrous sling that anchors the tendon of the digastric muscle to the hyoid bone, allowing proper movement of the anterior and posterior bellies.

Fibrous trabecula

A fibrous trabecula is a strand or band of connective tissue that extends within a tissue or organ, providing structural support, compartmentalization, and pathways for vessels or nerves.

Filiform papillae

Filiform papillae are the most numerous type of papillae on the dorsal surface of the tongue, primarily involved in mechanical functions rather than taste.

Fimbra of hippocampus

The fimbria of the hippocampus is a white matter tract that forms the initial part of the fornix, carrying axons from the hippocampus to subcortical structures.

Fimbriated fold

The fimbriated fold (or fimbriated edge/fimbriated border) refers to a thin, fringed mucosal structure in the female reproductive tract, located on the uterine (fallopian) tube near its opening into the peritoneal cavity. It plays an important role in capturing the oocyte during ovulation.

First thoracic vertebra (T1)

The first thoracic vertebra (T1) is the uppermost vertebra of the thoracic spine, marking the transition between the cervical and thoracic regions. It has unique features that reflect its hybrid role between cervical and thoracic vertebrae.

Flocculonodular lobe

The flocculonodular lobe is a part of the cerebellum primarily involved in balance, posture, and eye movements. It is considered the oldest (archicerebellar) part of the cerebellum and is closely linked to the vestibular system.

Flocculus

The flocculus is a small, rounded lobule of the cerebellum, forming part of the flocculonodular lobe, and plays a critical role in balance, posture, and coordination of eye movements.

Floor of nasal cavity

The floor of the nasal cavity forms the base of the nasal cavity, separating it from the oral cavity, and is composed of bony and soft tissue structures.

Fold over internal branch of superior laryngeal nerve

The fold over the internal branch of the superior laryngeal nerve refers to the mucosal fold in the larynx that covers and protects the nerve as it enters the larynx. It is also called the internal laryngeal nerve fold.

Folds of iris

The folds of the iris refer to the radial and circular ridges on the anterior surface of the iris, formed by collagen and smooth muscle fibers, which allow flexibility during pupil constriction and dilation.

Foliate papillae

Foliate papillae are a type of gustatory (taste) papillae located on the lateral margins of the tongue, specialized for taste sensation, particularly sour flavors.

Folium of superior vermis

The folium of the superior vermis is a small leaf-like lobule of the cerebellar vermis located in the superior (anterior) part of the cerebellum, involved in coordination of posture and axial muscles.

Folium of vermis of cerebellum

The folium of the vermis of the cerebellum refers to one of the narrow, leaf-like folds (folia) in the median vermis, which is the central part of the cerebellum connecting the two hemispheres. These folia increase the surface area of the cerebellar cortex and contribute to coordination of posture and movement.

Footplate of stapes

The footplate of the stapes is the base of the stapes bone in the middle ear, which sits in the oval window of the cochlea and transmits sound vibrations from the middle ear into the inner ear.

Foramen cecum

The foramen cecum is a small anatomical opening at the anterior part of the cranial base, with clinical and embryological significance. Its exact structure and significance vary depending on the context—cranial/skull anatomy vs. tongue/thyroid development.

Foramen cecum of frontal bone

The foramen cecum of the frontal bone is a small anatomical structure located at the anterior cranial base, connecting the frontal bone and the nasal cavity via a tiny canal. It is clinically and embryologically significant because it can transmit a small vein in early life, although it is often obliterated in adults.

Foramen for superior laryngeal vessels and internal branch of superior laryngeal nerve

The foramen for the superior laryngeal vessels and internal branch of the superior laryngeal nerve is actually a functional opening created by the thyrohyoid membrane, rather than a true bony foramen. It allows the internal branch of the superior laryngeal nerve (IBSLN) and accompanying superior laryngeal artery and vein to pass from the neck into the larynx.

Foramen lacerum

The foramen lacerum is a triangular opening at the base of the skull, located between the sphenoid, temporal, and occipital bones. It is largely filled with cartilage in living adults and serves mainly as a passageway for vessels and nerves rather than a direct route for major arteries.

Foramen magnum

The foramen magnum is the largest opening in the skull, located in the occipital bone, and serves as a critical conduit between the cranial cavity and the vertebral canal.

Foramen magnum of occipital bone

The foramen magnum of the occipital bone is the largest opening in the skull, located in the inferior part of the occipital bone, and serves as the key passage between the cranial cavity and vertebral canal.

Foramen ovale

The foramen ovale is an oval-shaped opening in the sphenoid bone at the base of the skull that allows important neurovascular structures to pass between the cranial cavity and the infratemporal fossa.

Foramen ovale of sphenoid bone

The foramen ovale of the sphenoid bone is an oval-shaped opening in the greater wing of the sphenoid, forming a passage between the middle cranial fossa and the infratemporal fossa for important nerves and vessels.

Foramen rotundum

The foramen rotundum is a circular opening in the sphenoid bone that connects the middle cranial fossa with the pterygopalatine fossa and allows passage of the maxillary nerve (V2).

Foramen spinosum of sphenoid bone

The foramen spinosum is a small, round opening in the sphenoid bone, located posterolateral to the foramen ovale, and it allows passage of the middle meningeal vessels and the meningeal branch of the mandibular nerve (V3) into the cranial cavity.

Foramen transversarium

The foramen transversarium (also called the transverse foramen) is a bony opening in the transverse processes of cervical vertebrae that transmits the vertebral artery, vertebral vein, and sympathetic nerve fibers. It is a key anatomical feature of the cervical spine.

Foramina of cranial base

The foramina of the cranial base are openings in the floor of the cranial cavity that allow passage of nerves, arteries, veins, and other structures between the cranial cavity and extracranial regions. They are grouped according to the cranial fossae they belong to: anterior, middle, and posterior cranial fossae.

Foramina of cribriform plate

Forming vertebral vein

The vertebral vein is a major venous channel of the neck that drains blood from the cervical vertebrae, spinal cord, and surrounding muscles, and eventually empties into the brachiocephalic vein. It is formed by the venous plexuses associated with the cervical vertebrae.

Fornix

The fornix is a major C-shaped white-matter fiber tract of the limbic system. It is the primary output pathway of the hippocampus, carrying hippocampal efferents to several deep brain structures—most importantly the mammillary bodies.

Fossa

In anatomy, a fossa is a depression, pit, or hollow in a bone or an organ.

Fossa for lacrimal sac

The fossa for the lacrimal sac is a vertical depression in the medial wall of the orbit that houses the lacrimal sac, an essential structure in the tear-drainage system.

Fossa of round (cochlear) window

The fossa of the round (cochlear) window—also called the round window niche—is a small depression in the medial wall of the middle ear that houses the round window membrane.

Fossa of round window

The fossa of the round window—also called the round window niche—is a small bony depression in the medial wall of the middle ear that houses and protects the round (cochlear) window membrane.

Fourth ventricle

The fourth ventricle is a diamond-shaped, CSF-filled cavity located in the hindbrain, between the pons and medulla anteriorly and the cerebellum posteriorly. It is part of the brain’s ventricular system and plays a major role in the circulation of cerebrospinal fluid (CSF).

Fovea centralis in macula (lutea)

The fovea centralis is the smallest, most specialized region of the retina, located in the center of the macula lutea. It provides the highest visual acuity and sharpest color vision in the human eye.

Frenulum of lower lip

The frenulum of the lower lip is a small midline mucosal fold that helps anchor the lower lip to the gums.

Frenulum of tongue

The frenulum of the tongue—also called the lingual frenulum—is a midline mucosal fold that connects the underside of the tongue to the floor of the mouth.

Frenulum of upper lip

The frenulum of the upper lip—also called the maxillary labial frenulum—is a midline mucosal fold that connects the inside of the upper lip to the upper gingiva.

Frontal (anterior) and parietal (posterior) branches of middle meningeal artery

The middle meningeal artery (MMA) is a major branch of the maxillary artery (from the external carotid artery) that supplies the dura mater and calvaria. It divides into frontal (anterior) and parietal (posterior) branches, which have distinct courses and clinical relevance.

Frontal (anterior) horn of left lateral ventricle

The frontal (anterior) horn of the lateral ventricle is the anterior part of the lateral ventricle located in the frontal lobe, forming part of the brain’s ventricular system, which contains cerebrospinal fluid (CSF).

Frontal and lacrimal nerves

The frontal and lacrimal nerves are branches of the ophthalmic division (V₁) of the trigeminal nerve (cranial nerve V). Both nerves supply sensory innervation to regions of the orbit, forehead, and lateral face, with some parasympathetic fibers traveling via the lacrimal nerve.

Frontal and parietal branches of superficial temporal artery

The superficial temporal artery (STA) is a terminal branch of the external carotid artery, which supplies scalp and lateral face regions. It divides into frontal (anterior) and parietal (posterior) branches, each with distinct courses and areas of supply.

Frontal and parietal tributaries of superficial temporal vein

The superficial temporal vein (STV) is the venous counterpart of the superficial temporal artery and drains the lateral scalp and temporal region. Its frontal and parietal tributaries collect blood from the forehead and parietal scalp, respectively.

Frontal belly (frontalis) of epicranius muscle

The frontal belly (frontalis) of the epicranius muscle is the anterior part of the occipitofrontalis muscle, responsible for raising the eyebrows and wrinkling the forehead.

Frontal belly (frontalis) of occipitofrontalis

The frontal belly (frontalis) of the epicranius muscle is the anterior part of the occipitofrontalis muscle, responsible for raising the eyebrows and wrinkling the forehead.

Frontal bone

The frontal bone is a single, unpaired cranial bone that forms the forehead, the superior part of the orbit, and part of the anterior cranial fossa. It plays a critical role in protecting the frontal lobes of the brain and supporting the structures of the face.

Frontal branch of superficial temporal artery

The frontal branch of the superficial temporal artery (STA) is the anterior terminal branch of the STA, a terminal branch of the external carotid artery, supplying the forehead and anterior scalp.

Frontal branches of superficial temporal artery and vein

The frontal branches of the superficial temporal artery and vein are the anterior divisions of the superficial temporal vessels that supply and drain the forehead and anterior scalp. They run together superficially over the temporal and frontal regions.

Frontal crest

The frontal crest is a midline bony ridge on the internal surface of the frontal bone that serves as an attachment point for the falx cerebri, a dural fold that separates the two cerebral hemispheres.

Frontal diploic vein

The frontal diploic vein is one of the diploic veins, which are valveless veins within the spongy (diploë) bone of the skull that communicate between the scalp, cranial bones, and dural venous sinuses.

Frontal lobe

The frontal lobe is the largest lobe of the cerebral hemisphere, located anterior to the central sulcus and superior to the lateral sulcus. It is primarily responsible for motor functions, executive functions, and higher cognitive processes.

Frontal nerve

The frontal nerve is the largest branch of the ophthalmic division (V₁) of the trigeminal nerve (cranial nerve V) and is purely sensory, supplying the forehead, upper eyelid, and scalp.

Frontal operculum

The frontal operculum is a region of the inferior frontal gyrus that covers the insula on the lateral surface of the frontal lobe. It plays a key role in language production and speech (in the dominant hemisphere).

Frontal pole

The frontal pole is the most anterior tip of the frontal lobe of the cerebral hemisphere. It represents the extreme anterior extension of the frontal lobe and is involved in high-level cognitive functions.

Frontal pole of cerebrum

Frontal process of maxilla

The frontal process of the maxilla is a vertical bony projection of the maxilla that extends upward to articulate with the frontal bone, forming part of the medial wall of the orbit, lateral wall of the nasal cavity, and the lacrimal fossa.

Frontal process of zygomatic bone

The frontal process of the zygomatic bone is a bony projection of the zygomatic bone that extends upward to articulate with the frontal bone, contributing to the lateral wall and lateral rim of the orbit.

Frontal sinus

The frontal sinus is a paired air-filled cavity within the frontal bone, located superior to the orbits. It is part of the paranasal sinus system and communicates with the nasal cavity to help lighten the skull, humidify inhaled air, and contribute to voice resonance.

Frontalis muscle

The frontalis muscle is the frontal (anterior) belly of the occipitofrontalis (epicranius) muscle and is primarily responsible for raising the eyebrows and wrinkling the forehead.

Fungiform papilla

The fungiform papilla is a type of tongue papilla that is mushroom-shaped, scattered across the dorsal surface of the tongue, and contains taste buds.

Furrow

In anatomy, a furrow is a narrow groove or linear depression on the surface of an organ, bone, or tissue. Furrows can serve as pathways for blood vessels, nerves, or other anatomical structures, or they may simply mark surface contours.

Galea aponeurotica of scalp

The galea aponeurotica (also called the epicranial aponeurosis) is a tendinous sheet connecting the frontal and occipital bellies of the occipitofrontalis muscle, forming a key part of the scalp’s layered anatomy.

Gallbladder and bile ducts

The gallbladder is a small, pear-shaped organ located on the undersurface of the liver that stores and concentrates bile produced by the liver before it is released into the small intestine, and bile ducts are a system of tubes that transport bile from the liver and gallbladder to the duodenum, allowing bile to participate in the digestion and absorption of fats. Collectively, they form the biliary tree.

Ganglion cells

Ganglion cells are neurons located in peripheral or central nervous system ganglia that serve as relay or processing centers for neural signals. They are key components in sensory, autonomic, and visual pathways, depending on their type.

Ganglion of trigeminal nerve

The trigeminal ganglion (also called Gasserian or semilunar ganglion) is the sensory ganglion of the trigeminal nerve (cranial nerve V). It contains the cell bodies of sensory neurons that transmit sensation from the face, oral and nasal cavities, and part of the meninges to the brainstem.

Ganglionic branches to pterygopalatine ganglion

The ganglionic branches to the pterygopalatine ganglion are small nerves that connect the trigeminal nerve (V2) to the pterygopalatine ganglion, carrying both sensory fibers and preganglionic parasympathetic fibers.

Gastric branches of anterior vagal trunk

The gastric branches of the anterior vagal trunk are parasympathetic fibers that supply the stomach, originating from the anterior vagal trunk as it passes through the esophageal hiatus into the abdomen.

Gastrointestinal tract

The gastrointestinal (GI) tract is a continuous muscular tube that extends from the mouth to the anus, responsible for ingestion, digestion, absorption of nutrients, and elimination of waste. It works together with accessory organs like the liver, pancreas, and gallbladder.

Geniculate bodies

The geniculate bodies are paired structures in the diencephalon that are part of the thalamus and serve as relay centers for sensory pathways—specifically, the visual and auditory systems. They are divided into lateral and medial geniculate bodies.

Geniculate ganglion

The geniculate ganglion is a sensory ganglion of the facial nerve (cranial nerve VII) located within the facial canal of the temporal bone. It contains the cell bodies of sensory neurons that transmit taste and general sensation from specific regions of the head.

Genioglossus muscle

The genioglossus muscle is a major extrinsic muscle of the tongue responsible for protrusion and depression of the tongue. It is essential for speech, swallowing, and maintaining airway patency.

Geniohyoid fascia

The geniohyoid fascia is a thin layer of connective tissue that covers the geniohyoid muscle, providing structural support and forming part of the floor of the mouth and upper neck fascial layers.

Geniohyoid muscle

The geniohyoid muscle is a small, paired suprahyoid muscle that lies deep to the mylohyoid muscle in the anterior neck. It helps elevate the hyoid bone and tongue during swallowing and speaking.

Genoglossus muscle

The genioglossus muscle is one of the extrinsic muscles of the tongue responsible primarily for tongue protrusion and depression. It is crucial for speech, swallowing, and airway maintenance.

Genu of corpus callosum

The genu of the corpus callosum is the anterior, curved part of the corpus callosum, a major white matter tract connecting the left and right cerebral hemispheres. It is primarily involved in interhemispheric communication between the frontal lobes.

Genu of internal capsule

The genu of the internal capsule is the anterior bend of the internal capsule, a major white matter structure in the brain that carries fibers between the cerebral cortex and subcortical structures. The genu is particularly important for motor and corticobulbar pathways.

Gingival (gum) epithelium (stratified)

The gingival (gum) epithelium is the stratified epithelial tissue covering the gums, providing a protective barrier against mechanical forces, microbial invasion, and chemical irritants in the oral cavity.

Gingival groove

The gingival groove (also called the gingival sulcus boundary) is a shallow linear depression on the external surface of the gingiva that demarcates the attached gingiva from the free (marginal) gingiva. It is an important anatomical landmark in periodontal anatomy.

Glabella

The glabella is the smooth, slightly depressed area of the forehead located between the eyebrows and just above the root of the nose. It is a prominent anatomical landmark used in craniofacial anatomy, neurology, and cosmetic assessments.

Globose cerebellar nuclei

The globose nucleus is one of the deep cerebellar nuclei, which are the primary output centers of the cerebellum, involved in coordination of voluntary movements. It lies medial to the dentate nucleus and lateral to the emboliform nucleus, forming part of the interposed nuclei.

Globus pallidus of lentiform nucleus

The globus pallidus is a component of the lentiform (lenticular) nucleus in the basal ganglia, which is part of the extrapyramidal motor system. It plays a key role in regulating voluntary movement by influencing thalamocortical pathways.

Glomerulus

In anatomy, a glomerulus refers to a network of capillaries involved in filtration or sensory processing, depending on the context. It is most commonly discussed in the kidney (renal glomerulus) and the olfactory system (olfactory glomerulus).

Glossopharyngeal (IX) nerve

The glossopharyngeal nerve (cranial nerve IX) is a mixed cranial nerve with sensory, motor, and parasympathetic components, playing important roles in taste, swallowing, salivation, and carotid body reflexes.

Glossopharyngeal part of superior pharyngeal constrictor

The glossopharyngeal part of the superior pharyngeal constrictor refers to the portion of the superior pharyngeal constrictor muscle that receives innervation or functional influence from the glossopharyngeal nerve (CN IX), particularly via its motor fibers contributing to swallowing and pharyngeal movement.

Gracile fasciculus

The gracile fasciculus is a major ascending (sensory) pathway in the posterior (dorsal) column of the spinal cord. It carries fine touch, vibration, and conscious proprioception information from the lower half of the body to the brain.

Gracile tubercle

The gracile tubercle is a raised area on the dorsal surface of the medulla oblongata, marking the location of the gracile nucleus underneath. It is an important landmark in neuroanatomy, especially for the dorsal column–medial lemniscus pathway.

Granular foveolae (for arachnoid granulations)

Granular foveolae are small depressions on the inner surface of the cranial vault that house arachnoid granulations, which are structures responsible for cerebrospinal fluid (CSF) absorption into the venous system.

Granule cell

A granule cell is a small, densely packed neuron found in several areas of the central nervous system, most notably in the cerebellum and the hippocampus. Granule cells are crucial for information processing, synaptic integration, and neural circuit modulation.

Gray rami communicantes

The gray rami communicantes are postganglionic sympathetic nerve fibers that connect the sympathetic trunk (paravertebral ganglia) to spinal nerves, allowing sympathetic signals to reach target organs in the body wall and limbs.

Great auricular nerve (C2, 3)

The great auricular nerve is a cutaneous branch of the cervical plexus (C2–C3) that provides sensory innervation to parts of the external ear and surrounding skin.

Great cerebral vein (of Galen)

The great cerebral vein, also known as the vein of Galen, is a short but large deep cerebral vein that drains blood from the deep structures of the brain into the straight sinus.

Greater (descending) palatine artery

The greater (descending) palatine artery is a branch of the maxillary artery that supplies the hard palate and palatal mucosa, as well as some posterior gingiva.

Greater and lesser palatine foramina

The greater and lesser palatine foramina are openings in the posterior part of the hard palate that allow the passage of palatine nerves and arteries from the pterygopalatine fossa into the oral cavity.

Greater and lesser palatine nerves (V2)

The greater and lesser palatine nerves are branches of the maxillary nerve (V2, from the trigeminal nerve) that provide sensory innervation to the hard and soft palate, respectively.

Greater horn of hyoid bone

The greater horn (greater cornu) of the hyoid bone is a lateral, elongated projection from the body of the hyoid that provides attachment sites for muscles and ligaments in the neck.

Greater occipital nerve (C2)

The greater occipital nerve is a cutaneous branch of the dorsal ramus of the second cervical spinal nerve (C2) that provides sensory innervation to the posterior scalp and upper neck.

Greater palatine artery

The greater palatine artery (also called the descending palatine artery) is a branch of the maxillary artery that supplies the hard palate, palatal mucosa, and posterior gingiva.

Greater palatine foramen

The greater palatine foramen is a bony opening in the posterior hard palate that allows passage of the greater palatine nerve and artery from the pterygopalatine fossa to the oral cavity.

Greater palatine nerve (V2)

The greater palatine nerve is a branch of the maxillary nerve (V2, from the trigeminal nerve) that provides sensory innervation to the hard palate and posterior gingiva.

Greater palatine nerve and vessels of greater palatine foramen

The greater palatine nerve and vessels pass through the greater palatine foramen to supply the hard palate and posterior gingiva.

Greater palatine nerve of maxillary nerve

The greater palatine nerve is a sensory branch of the maxillary nerve (V2) that supplies the hard palate and posterior palatal gingiva.

Greater palatine nerves (V2)

The greater palatine nerves are branches of the maxillary nerve (V2) that provide sensory innervation to the hard palate and posterior palatal gingiva.

Greater petrosal nerve

The greater petrosal nerve is a branch of the facial nerve (cranial nerve VII) that carries pre-ganglionic parasympathetic fibers to the lacrimal gland, nasal cavity, and palate, along with some taste fibers.

Greater petrosal nerve of foramen lacerum

The greater petrosal nerve passes over the foramen lacerum on its way from the geniculate ganglion of CN VII to the pterygoid canal. It carries preganglionic parasympathetic fibers and some taste fibers.

Greater petrosal nerve of pterygopalatine ganglion

The greater petrosal nerve is a branch of the facial nerve (CN VII) that carries preganglionic parasympathetic fibers to the pterygopalatine ganglion, which then distributes these fibers to the lacrimal gland, nasal cavity, and palate.

Greater wing of the sphenoid

The greater wing of the sphenoid bone is a large, paired lateral projection of the sphenoid bone that forms part of the floor and lateral wall of the cranial cavity, as well as portions of the orbit and infratemporal fossa.

Groove for anterior meningeal vessels of frontal bone

The groove for the anterior meningeal vessels of the frontal bone is a shallow channel on the internal (endocranial) surface of the frontal bone that accommodates the anterior meningeal arteries and veins, which supply the anterior cranial fossa and dura mater.

Groove for C7 spinal nerve

The groove for the C7 spinal nerve is a bony or cartilaginous notch or sulcus on the vertebrae (typically the C7 vertebra) through which the C7 spinal nerve root passes as it exits the spinal canal.

Groove for greater petrosal nerve

The groove for the greater petrosal nerve is a shallow channel on the anterior surface of the petrous part of the temporal bone that guides the greater petrosal nerve (branch of CN VII) as it travels from the geniculate ganglion toward the foramen lacerum.

Groove for inferior petrosal sinus of occipital bone

The groove for the inferior petrosal sinus is a shallow sulcus on the inferior surface of the petrous part of the temporal bone and the occipital bone, which accommodates the inferior petrosal sinus, a dural venous sinus connecting the cavernous sinus to the internal jugular vein.

Groove for lesser petrosal nerve of petrous part of temporal bone

The groove for the lesser petrosal nerve is a shallow sulcus on the superior surface of the petrous part of the temporal bone that guides the lesser petrosal nerve (a branch of CN IX) as it travels from the tympanic plexus to the otic ganglion.

Groove for middle meningeal vessels (frontal branches) of greater wing of sphenoid bone

The groove for the middle meningeal vessels (frontal branches) is a shallow sulcus on the internal (endocranial) surface of the greater wing of the sphenoid bone, which accommodates the frontal branches of the middle meningeal artery and accompanying veins as they supply the dura mater of the anterior and middle cranial fossae.

Groove for middle meningeal vessels (parietal branches) of parietal bone

The groove for the middle meningeal vessels (parietal branches) is a shallow sulcus on the internal (endocranial) surface of the parietal bone, which accommodates the parietal branches of the middle meningeal artery and accompanying veins as they supply the dura mater of the parietal region.

Groove for occipital sinus of occipital bone

The groove for the occipital sinus is a shallow sulcus on the internal (endocranial) surface of the occipital bone, which accommodates the occipital sinus, a small dural venous sinus that drains the posterior cranial fossa into the confluence of sinuses.

Groove for posterior deep temporal artery of temporal bone

The groove for the posterior deep temporal artery is a shallow sulcus on the internal surface of the temporal bone that accommodates the posterior deep temporal artery, a branch of the maxillary artery, which supplies the temporalis muscle.

Groove for posterior meningeal vessels of occipital bone

The groove for the posterior meningeal vessels is a shallow bony groove located on the internal surface of the occipital bone, typically near the jugular foramen. It transmits the posterior meningeal artery, vein, and accompanying small nerves.

Groove for sigmoid sinus of petrous part of temporal bone

The groove for the sigmoid sinus is a prominent, curved depression located on the intracranial (endocranial) surface of the petrous part of the temporal bone, forming part of the sigmoid sinus sulcus that continues onto the occipital bone.

Groove for spinal nerve (C4)

The groove for the C4 spinal nerve is a shallow bony groove located on the superior surface of the C5 vertebra, where the C4 spinal nerve exits the vertebral canal through the C4–C5 intervertebral foramen.

Groove for spinal nerve in transverse process

In the cervical spine, the “groove for the spinal nerve” is a distinct anatomical feature located on the superior surface of the transverse process of typical cervical vertebrae (C3–C6).

Groove for superior petrosal sinus of occipital bone

This is a shallow venous groove located on the posterior cranial fossa surface of the occipital bone where it helps lodge part of the superior petrosal sinus, a dural venous sinus.

Groove for superior petrosal sinus of petrous part of temporal bone

The groove for the superior petrosal sinus is a well-defined venous sulcus located on the superior border of the petrous part of the temporal bone, within the posterior cranial fossa.

It houses the superior petrosal sinus, one of the major dural venous sinuses connecting the cavernous sinus to the transverse sinus.

Groove for superior sagittal sinus

The groove for the superior sagittal sinus is a long, shallow midline sulcus on the internal surface of the calvaria, formed by the presence of the superior sagittal sinus, one of the major dural venous sinuses.

Groove for superior sagittal sinus of frontal bone

The groove for the superior sagittal sinus on the frontal bone is the anterior portion of the long midline endocranial groove created by the superior sagittal sinus.

Groove for superior sagittal sinus of occipital bone

The groove for the superior sagittal sinus on the occipital bone is the posterior continuation of the long midline venous groove that carries the superior sagittal sinus as it approaches the confluence of sinuses.

Groove for transverse sinus of occipital bone

The groove for the transverse sinus on the occipital bone is a prominent venous impression on the internal surface of the bone that houses the transverse sinus, one of the major dural venous sinuses of the cranial cavity.

Groove for vertebral artery

The groove for the vertebral artery is a bony impression on the posterior arch of the atlas (C1 vertebra) that accommodates the vertebral artery as it courses toward the cranial cavity. This groove is an important landmark in cervical spine anatomy and neurovascular surgery.

Grooves for branches of middle meningeal vessels

The grooves for the middle meningeal artery and vein are impressions on the internal surface of the cranial bones (mainly the parietal and greater wing of the sphenoid bones) that accommodate the middle meningeal vessels, which are major suppliers of the dura mater.

Habenula

The habenula is a paired, small epithalamic nucleus located in the dorsomedial thalamus, part of the diencephalon. It is an important relay between the limbic system and midbrain monoaminergic centers.

Habenular commissure

The habenular commissure (also called the habenular commissural fibers or commissure of the habenulae) is a small fiber tract that connects the left and right habenular nuclei across the midline.

Habenular trigone

The habenular trigone (also called the trigonum habenulae) is a small triangular area of the epithalamus that contains the habenular nuclei and associated fiber pathways.

Hamulus

Hamulus means “little hook” in Latin, and in anatomy it refers to several different hook-shaped structures. The most commonly referenced one is the pterygoid hamulus, but there are a few others.

Hamulus of medial plate of pterygoid process of sphenoid bone

The hamulus of the medial plate of the pterygoid process—usually called the pterygoid hamulus—is a small, hook-shaped bony projection at the inferior end of the medial pterygoid plate of the sphenoid bone.

Hamulus of spiral lamina

The hamulus of the spiral lamina is a small anatomical feature of the cochlea in the inner ear. It is part of the osseous (bony) spiral lamina, the structure that partially divides the cochlear canal and supports the basilar membrane.

Handle of malleus

The handle of the malleus—also called the manubrium of the malleus—is the long, slender, downward-projecting part of the malleus that is firmly attached to the tympanic membrane.

Hard palate

The hard palate is the bony anterior portion of the roof of the mouth and the floor of the nasal cavity. It forms a rigid partition between the oral and nasal cavities.

Head of caudate nucleus

The head of the caudate nucleus is the large, anterior, bulbous portion of the caudate nucleus, one of the major basal ganglia structures involved in motor control, learning, and associative cognition.

Head of condylar process

The head of the condylar process is the rounded superior end of the condylar process (condyle) of the mandible, which articulates with the temporal bone to form the temporomandibular joint (TMJ).

Head of malleus

The head of the malleus is the bulbous, superior part of the malleus, one of the three auditory ossicles in the middle ear. It is located deep in the tympanic cavity and articulates with the incus, forming part of the ossicular chain that transmits sound vibrations from the tympanic membrane to the inner ear.

Head of mandible

The head of the mandible is the rounded, superior end of the mandibular condylar process that articulates with the temporal bone at the temporomandibular joint (TMJ). It is sometimes simply called the mandibular condyle.

Heads of caudate nuclei

The heads of the caudate nuclei are the anterior, enlarged portions of the caudate nuclei, which are key components of the basal ganglia. They are involved in cognitive, emotional, and motor functions.

Heart

The heart is a muscular organ that functions as the central pump of the circulatory system, propelling blood through the systemic and pulmonary circuits to deliver oxygen and nutrients to tissues and remove waste products.

Helicotrema

The helicotrema is a key anatomical feature of the cochlea in the inner ear. It is the apical opening that connects the scala vestibuli and scala tympani, allowing perilymph fluid to move between these two chambers.

Helix

The helix is a prominent anatomical feature of the external ear (auricle/pinna). It is the outer rim of the ear that forms its curved, cartilaginous border.

Hepatic branch of anterior vagal trunk (in lesser omentum)

The hepatic branch of the anterior vagal trunk is an important parasympathetic nerve branch that runs within the lesser omentum toward the liver, gallbladder, and biliary tree. It originates from the anterior vagal trunk as it passes through the esophageal hiatus.

Hepatic plexus

The hepatic plexus is the autonomic nerve network that supplies the liver, gallbladder, and biliary tree, formed by contributions from both sympathetic and parasympathetic fibers.

Hiatus for greater petrosal nerve

The hiatus for the greater petrosal nerve is a small opening in the petrous part of the temporal bone that serves as the exit point for the greater petrosal nerve from the facial canal.

Hiatus for lesser petrosal nerve

The hiatus for the lesser petrosal nerve is a small opening in the petrous part of the temporal bone that serves as the exit for the lesser petrosal nerve from the middle cranial fossa to the otic ganglion.

Highest nasal concha of ethmoid bone

The highest nasal concha (also called the supreme nasal concha) is a small, variably present bony projection from the superior part of the lateral wall of the nasal cavity, part of the ethmoid bone. It lies superior to the superior nasal concha.

Hippocampal and inferior ventricular veins

The hippocampal veins and inferior ventricular veins are cerebral veins associated with the temporal lobe and lateral ventricles, draining blood from deep structures of the brain into the basal venous system.

Hippocampal fimbria

The fimbria of the hippocampus is a bundle of white matter fibers that forms part of the output pathway of the hippocampus, connecting it to the fornix and ultimately to other subcortical structures.

Hippocampal sulcus

The hippocampal sulcus is a shallow groove in the medial temporal lobe of the brain, separating the dentate gyrus from the subiculum in the hippocampal formation. It is mainly a developmental and anatomical landmark rather than a functional structure.

Hippocampus

The hippocampus is a curved, seahorse-shaped structure in the medial temporal lobe of the brain, forming a key part of the limbic system. It plays a critical role in memory formation, spatial navigation, and emotional processing.

Horizontal cells

Horizontal cells are specialized interneurons in the retina that play a critical role in processing visual information by mediating lateral interactions between photoreceptors.

Horizontal fissure of anterior lobe of cerebellum

The horizontal fissure of the anterior lobe of the cerebellum is a major anatomical groove that separates parts of the cerebellar cortex, running transversely across the cerebellum.

Horizontal fissure of posterior lobe of cerebellum

The horizontal fissure of the posterior lobe of the cerebellum is the deepest and longest fissure of the cerebellum, running transversely to separate the superior and inferior surfaces of the posterior lobe. It serves as an important anatomical landmark for cerebellar lobules.

Horizontal plate of palatine bone

The horizontal plate of the palatine bone is a flat, horizontal bony structure that forms the posterior part of the hard palate and contributes to the floor of the nasal cavity.

Hyaloid canal

The hyaloid canal is a narrow, tubular channel within the vitreous body of the eye, running from the optic disc (optic nerve head) to the posterior surface of the lens. It is most prominent during fetal development.

Hyoepiglottic ligament

The hyoepiglottic ligament is a fibrous ligament connecting the epiglottis to the hyoid bone, playing an important role in the movement of the epiglottis during swallowing.

Hyoglossus

The hyoglossus is a thin, flat muscle of the tongue that acts to depress and retract the tongue. It is one of the extrinsic muscles of the tongue, connecting the tongue to the hyoid bone.

Hyoid bone

The hyoid bone is a U-shaped, mobile bone in the anterior neck that serves as an attachment site for tongue and neck muscles. It is unique in that it does not articulate directly with any other bone.

Hyoid bone (tip of greater horn)

The tip of the greater horn (cornu) of the hyoid bone refers to the distal, posterior end of the greater horn, which serves as an attachment point for muscles and ligaments involved in tongue, pharyngeal, and laryngeal movements.

Hyophysis (pituitary gland) in sella turcica

The hypophysis, or pituitary gland, is a small, pea-sized endocrine gland that sits in the sella turcica of the sphenoid bone. It is a key regulator of multiple hormonal systems in the body.

Hypoglossal canal

The hypoglossal canal is a bony passage in the occipital bone through which the hypoglossal nerve (cranial nerve XII) exits the skull. It also transmits a venous plexus connecting the intracranial and extracranial venous systems.

Hypglossal nerve (XII)

The hypoglossal nerve (cranial nerve XII) is closely related to the hyoid bone because several muscles attached to the hyoid are innervated by it, particularly the extrinsic muscles of the tongue.

Hypoglossal nucleus

The hypoglossal nucleus is the cranial nerve nucleus in the brainstem that gives rise to the hypoglossal nerve (cranial nerve XII), which innervates the intrinsic and extrinsic muscles of the tongue.

Hypoglossal trigone

The hypoglossal trigone is a surface landmark on the floor of the fourth ventricle that marks the location of the underlying hypoglossal nucleus.

Hypophyseal fossa

The hypophyseal fossa is a depression in the sphenoid bone that houses the pituitary gland (hypophysis). It is the central part of the sella turcica.

Hypophysis (pituitary gland)

The hypophysis, also called the pituitary gland, is a pea-sized endocrine gland located at the base of the brain in the sella turcica of the sphenoid bone. It is often referred to as the “master gland” because it regulates multiple hormonal systems in the body.

Hypothalamic artery

The term “hypothalamic artery” usually refers to the arterial branches supplying the hypothalamus, which are small branches of the circle of Willis and its neighboring arteries. These arteries are critical for delivering oxygenated blood to the hypothalamus, which regulates autonomic, endocrine, and behavioral functions.

Hypothalamic sulcus

The hypothalamic sulcus is a groove on the lateral wall of the third ventricle that separates the thalamus (dorsal) from the hypothalamus (ventral). It is an important landmark in brain anatomy.

Hypothalamic vessels

The term “hypothalamic vessels” refers to the arteries and veins supplying the hypothalamus, which is a highly vascularized region of the brain responsible for endocrine, autonomic, and homeostatic functions.

Hypothalamohypophyseal tract

The hypothalamohypophyseal tract is a bundle of nerve fibers connecting the hypothalamus to the posterior pituitary (neurohypophysis), responsible for transporting hormones synthesized in the hypothalamus to the posterior lobe of the pituitary gland.

Hypothalamus

The hypothalamus is a small but critical part of the diencephalon located below the thalamus. It plays a central role in homeostasis, autonomic regulation, endocrine control, and behavior.

Incisive canal of maxilla

The incisive canal (also called the nasopalatine canal) is a bony canal in the anterior maxilla that connects the nasal cavity to the oral cavity. It transmits neurovascular structures important for the anterior palate and maxillary anterior teeth.

Incisive fossa of maxilla

The incisive fossa is a depression in the anterior part of the hard palate, just behind the maxillary central incisors, marking the oral opening of the incisive canal.

Incisive papilla

The incisive papilla is a small, raised mucosal prominence on the anterior hard palate, covering the oral opening of the incisive canal. It serves as an important landmark in dental and oral anatomy.

Inconspicuous anterior tubercle (transverse process)

The inconspicuous anterior tubercle of the transverse process is a small bony prominence on the anterior part of the transverse process of a cervical vertebra, typically C3–C6. It serves as an attachment site for muscles and ligaments of the neck.

Incisive canal

The incisive canal, also called the nasopalatine canal, is a bony passage in the anterior maxilla connecting the nasal cavity to the oral cavity. It transmits important neurovascular structures to the anterior palate.

Incus

The incus is one of the three auditory ossicles in the middle ear, situated between the malleus and the stapes. It plays a key role in transmitting sound vibrations from the tympanic membrane to the inner ear.

Inferior (inferolateral) margin of cerebrum

The inferior (inferolateral) margin of the cerebrum refers to the lower-lateral border of the cerebral hemispheres, which forms part of the boundary between the cerebral cortex and the basal structures, and lies above the temporal lobe and cranial base.

Inferior alveolar artery

The inferior alveolar artery is a branch of the maxillary artery that supplies the mandible, lower teeth, and chin region. It travels through the mandibular canal along with the inferior alveolar nerve.

Inferior alveolar nerve (V3)

The inferior alveolar nerve is a branch of the mandibular nerve (CN V3) that provides sensory innervation to the mandibular teeth, lower lip, and chin, and gives off a motor branch to the mylohyoid muscle.

Inferior alveolar nerve entering mandibular foramen

The inferior alveolar nerve entering the mandibular foramen is a key anatomical event in the course of this nerve as it travels to supply the mandibular teeth and chin.

Inferior alveolar nerve of mandibular nerve

The inferior alveolar nerve is a branch of the mandibular nerve (CN V3), the third division of the trigeminal nerve, responsible for sensory innervation of the mandibular teeth, lower lip, and chin, and also provides a motor branch (mylohyoid nerve).

Inferior alveolar nerves

The inferior alveolar nerves are the paired branches of the mandibular nerves (CN V3) that provide sensory innervation to the mandibular teeth, gingiva, lower lip, and chin, with a motor branch (mylohyoid nerve) for the mylohyoid muscle and anterior belly of the digastric.

Inferior alveolar vein

The inferior alveolar vein is a venous vessel that accompanies the inferior alveolar artery and nerve through the mandibular canal, draining blood from the mandibular teeth, mandible, and chin region into the pterygoid venous plexus.

Inferior anastomotic vein (of Labbe)

The inferior anastomotic vein (of Labbe) is an important superficial cerebral vein that provides venous drainage from the lateral surface of the cerebral hemisphere to the transverse sinus.

Inferior articular process (C3)

The inferior articular process of C3 is a bony projection from the lamina-pedicle junction of the third cervical vertebra, forming part of the facet (zygapophyseal) joint with the vertebra below (C4).

Inferior articular facet for C3

The inferior articular facet of C3 is the smooth articular surface on the inferior articular process of the third cervical vertebra, which forms a zygapophyseal (facet) joint with the superior articular facet of C4.

Inferior articular facet for T1

The inferior articular facet of T1 is the smooth surface on the inferior articular process of the first thoracic vertebra, which forms a zygapophyseal (facet) joint with the superior articular facet of T2.

Inferior articular process

The inferior articular process is a bony projection from a vertebra that extends downward from the junction of the pedicle and lamina, forming a zygapophyseal (facet) joint with the superior articular process of the vertebra below.

Inferior articular surface of lateral mass for axis

The inferior articular surface of the lateral mass of the axis (C2) is the smooth, articular facet on the inferior aspect of each lateral mass that articulates with the superior articular facet of C3, forming part of the zygapophyseal (facet) joint.

Inferior aspect of C3

The inferior aspect of C3 refers to the lower surface of the third cervical vertebra (C3), which includes the inferior vertebral body surface and the inferior articular facets that articulate with the superior articular facets of C4 to form the zygapophyseal (facet) joints.

Inferior belly

The term “inferior belly” refers to the lower portion of a muscle that has two separate parts, or “bellies,” often connected by a tendon or intermediate portion. This terminology is used in muscles where there is an anterior/posterior or superior/inferior division, such as the omohyoid, digastric, or sternohyoid.

Inferior branch of oculomotor nerve (III)

The inferior branch of the oculomotor nerve (cranial nerve III) is one of the two primary divisions of CN III after it enters the orbit via the superior orbital fissure. It primarily supplies extraocular muscles responsible for eye movement and carries parasympathetic fibers to the ciliary ganglion.

Inferior bulb of internal jugular vein

The inferior bulb of the internal jugular vein is the dilated lower portion of the internal jugular vein at its junction with the subclavian vein, just before it joins to form the brachiocephalic vein. It is a key structure in venous drainage from the brain.

Inferior cerebellar hemispheric veins

The inferior cerebellar hemispheric veins are superficial veins that drain the inferior surface of the cerebellar hemispheres into the venous sinuses of the posterior cranial fossa, primarily the transverse, sigmoid, and superior petrosal sinuses.

Inferior cerebellar peduncle

The inferior cerebellar peduncle is a large bundle of nerve fibers connecting the medulla oblongata and spinal cord to the cerebellum, transmitting afferent (mostly sensory) signals that are essential for coordination, balance, and proprioception.

Inferior cerebral vein

The inferior cerebral veins are superficial veins that drain the inferior surfaces of the cerebral hemispheres, including the temporal and orbital surfaces, into the dural venous sinuses such as the cavernous, transverse, and superior petrosal sinuses.

Inferior cervical cardiac branch of vagus nerve

The inferior cervical cardiac branch of the vagus nerve is a parasympathetic branch of the vagus nerve (CN X) that contributes to the cardiac (heart) plexus, helping regulate heart rate and cardiac function.

Inferior cervical sympathetic cardiac nerve

The inferior cervical sympathetic cardiac nerve is a branch of the cervical sympathetic trunk that carries postganglionic sympathetic fibers to the cardiac plexus, contributing to autonomic regulation of the heart.

Inferior colliculi

The inferior colliculi are paired structures located in the midbrain (mesencephalon) that form part of the tectum and serve as a major relay center for the auditory pathway.

Inferior concha

The inferior concha (also called the inferior nasal concha or inferior turbinate) is a separate bone of the nasal cavity that forms the inferior-most scroll-like projection along the lateral wall of the nasal cavity, helping to direct airflow, humidify, and filter inspired air.

Inferior conjunctival fornix

The inferior conjunctival fornix is the recess formed by the reflection of the bulbar conjunctiva onto the palpebral conjunctiva in the lower part of the eyelid, allowing free movement of the eyeball.

Inferior deep lateral cervical (scalene) node

The inferior deep lateral cervical (scalene) lymph node is a deep cervical lymph node located along the lower part of the lateral neck, near the scalene muscles, which serves as a terminal node receiving lymph from the head and neck before draining into the thoracic duct or right lymphatic duct.

Inferior dental plexus of mandibular nerve

The inferior dental plexus is a network of nerve fibers formed by branches of the inferior alveolar nerve, which is itself a branch of the mandibular nerve (CN V₃). It supplies sensory innervation to the lower teeth, the mandibular alveolar process, and associated structures.

Inferior division of oculomotor nerve

The inferior division of the oculomotor nerve (CN III) is one of the two divisions of CN III within the orbit, primarily responsible for motor innervation of certain extraocular muscles and parasympathetic innervation to the eye.

Inferior division of vestibular nerve

The inferior division of the vestibular nerve is a branch of the vestibular nerve (part of cranial nerve VIII) that primarily carries sensory information from the vestibular apparatus—specifically the saccule and the posterior semicircular canal—to the vestibular nuclei in the brainstem for balance and spatial orientation.

Inferior fovea

The inferior fovea is a small depression or pit on a bone or organ, but in anatomical context, it most commonly refers to a depression on the internal surface of the posterior cranial fossa or the floor of a cavity that serves as a site of attachment or passage for structures.

Inferior frontal gyrus

The inferior frontal gyrus (IFG) is a prominent structure of the frontal lobe of the brain, located on the lateral surface of the hemisphere, and is involved in language, speech production, and higher cognitive functions.

Inferior frontal sulcus

The inferior frontal sulcus is a groove on the lateral surface of the frontal lobe that separates the inferior frontal gyrus (IFG) from the middle frontal gyrus (MFG). It is an important anatomical landmark in neuroanatomy for identifying frontal lobe subdivisions.

Inferior ganglia of glossopharyngeal nerve

The inferior ganglion of the glossopharyngeal nerve (CN IX), also called the petrosal ganglion, is a sensory ganglion located on the glossopharyngeal nerve, containing cell bodies of sensory neurons that carry general, special, and visceral sensory information.

Inferior ganglion

The term “inferior ganglion” generally refers to the smaller, lower ganglion of a cranial nerve that primarily contains sensory neuron cell bodies. Its exact identity depends on which cranial nerve is being discussed.

Inferior ganglion of vagus nerve

The inferior ganglion of the vagus nerve (CN X), also called the nodose ganglion, is a sensory ganglion containing the cell bodies of visceral and general sensory neurons that convey information from the pharynx, larynx, thoracic, and abdominal viscera to the brainstem.

Inferior horn of thyroid cartilage

The inferior horn of the thyroid cartilage is a downward projection of the thyroid cartilage that articulates with the cricoid cartilage, forming part of the cricothyroid joint, which is crucial for tension and length adjustment of the vocal cords.

Inferior hypophyseal artery

The inferior hypophyseal artery is a branch of the cavernous segment of the internal carotid artery that primarily supplies the posterior lobe (neurohypophysis) of the pituitary gland.

Inferior labial artery

The inferior labial artery is a branch of the facial artery that supplies the lower lip and adjacent structures, providing oxygenated blood to the muscles, skin, and mucosa of the lower lip.

Inferior labial vein

The inferior labial vein is the venous counterpart of the inferior labial artery, responsible for draining blood from the lower lip and directing it into the facial vein, which then drains into the internal jugular vein.

Inferior lacrimal papilla and punctum

The inferior lacrimal papilla and punctum are small structures in the medial part of the eyelid that play a key role in tear drainage from the eye into the lacrimal system.

Inferior lateral nasal nerves

The inferior lateral nasal nerves are branches of the maxillary division of the trigeminal nerve (CN V₂) that provide sensory innervation to the skin of the lower lateral part of the nose.

Inferior lateral palpebral artery

The inferior lateral palpebral artery is a branch of the ophthalmic artery (via the lacrimal artery) that supplies the lower eyelid, lateral portion, and adjacent structures, forming an arterial arcade with its medial counterpart.

Inferior longitudinal muscle of tongue

The inferior longitudinal muscle of the tongue is one of the intrinsic muscles of the tongue, responsible for shortening the tongue and curling its tip downward.

Inferior longitudinal band of cruciate ligament

The inferior longitudinal band of the cruciate ligament is a component of the cruciate ligament of the atlas (C1) in the cervical spine, which helps stabilize the dens (odontoid process) of the axis (C2) against the anterior arch of the atlas.

Inferior longitudinal muscle of tongue

The inferior longitudinal muscle of the tongue is one of the intrinsic muscles of the tongue, running along its ventral (undersurface) aspect. It primarily functions to shorten the tongue and pull its tip downward.

Inferior longitudinal of intrinsic muscles of tongue

The inferior longitudinal muscle of the tongue is one of the intrinsic muscles of the tongue, responsible for shortening the tongue and pulling its tip downward.

Inferior macular arteriole and venule

The inferior macular arteriole and venule are the small blood vessels supplying and draining the inferior portion of the macula in the retina, which is responsible for central vision.

Inferior medial palpebral artery

The inferior medial palpebral artery is a branch of the ophthalmic artery that supplies the medial portion of the lower eyelid, forming an arterial arcade with the inferior lateral palpebral artery to provide blood to the eyelid and associated structures.

Inferior medullary velum

The inferior medullary velum is a thin sheet of white matter in the cerebellum that forms part of the roof of the fourth ventricle and connects the nodule of the vermis to the flocculi.

Inferior nasal concha (turbinate)

The inferior nasal concha (or inferior turbinate) is a separate, scroll-shaped bone in the lateral wall of the nasal cavity that plays a key role in airflow regulation, humidification, and filtration of inspired air.

Inferior nasal meatus

The inferior nasal meatus is a passage in the nasal cavity located below the inferior nasal concha (turbinate). It is an important route for nasolacrimal duct drainage and part of the nasal airflow pathway.

Inferior nasal retinal arteriole and venule

The inferior nasal retinal arteriole and venule are the small blood vessels supplying and draining the inferior nasal quadrant of the retina, part of the central retinal vascular system. They are crucial for maintaining retinal oxygenation and metabolism in that region.

Inferior nuchal line

The inferior nuchal line is a bony ridge on the external surface of the occipital bone that serves as an attachment site for muscles of the posterior neck and head.

Inferior nuchal line of occipital bone

The inferior nuchal line is a bony ridge located on the posterior surface of the occipital bone in the skull.

Inferior oblique muscle of oculomotor nerve (III)

The inferior oblique muscle is indeed one of the extraocular muscles innervated by the oculomotor nerve (cranial nerve III), specifically its inferior division.

Inferior ophthalmic vein

The inferior ophthalmic vein is a key venous structure in the orbit that drains blood from the eye and orbital contents.

Inferior orbital fissure

The inferior orbital fissure is an important anatomical feature of the orbit that serves as a passageway for nerves and vessels.

Inferior palpebral conjunctiva

The inferior palpebral conjunctiva is part of the mucous membrane lining the eyelids and contributing to the ocular surface.

Inferior parathyroid gland

The inferior parathyroid glands are small endocrine glands located in the neck that play a critical role in calcium homeostasis.

Inferior parietal lobule

The inferior parietal lobule (IPL) is a key cortical region in the parietal lobe of the brain, involved in sensory integration, language, and spatial awareness.

Inferior part of vestibular nerve (from saccule and posterior membranous ampulla

The inferior part of the vestibular nerve is a branch of the vestibulocochlear nerve (CN VIII) that carries sensory information from specific structures in the inner ear.

Inferior petrosal sinus

The inferior petrosal sinus (IPS) is an important dural venous sinus that connects the cavernous sinus to the internal jugular vein.

Inferior petrosal sinus of jugular foramen

The inferior petrosal sinus (IPS) is a dural venous sinus that passes through the jugular foramen to drain into the internal jugular vein.

Inferior petrosal sinus of jugular fossa

The inferior petrosal sinus (IPS) is a dural venous sinus that courses through the jugular fossa to drain into the internal jugular vein.

Inferior pharyngeal constrictor muscle

The inferior pharyngeal constrictor muscle is the lowest of the three pharyngeal constrictors and plays a key role in swallowing (deglutition).

Inferior rectus muscle of oculomotor nerve (III)

The inferior rectus muscle is one of the six extraocular muscles that control eye movement.

Inferior retrotonsillar vein of cerebellomedullary cistern

The inferior retrotonsillar vein is a small venous structure located in the cerebellomedullary cistern region of the posterior cranial fossa.

Inferior root of ansa cervicalis

The inferior root of the ansa cervicalis is a key component of the cervical plexus that contributes to motor innervation of several infrahyoid (“strap”) muscles in the neck.

Inferior sagittal sinus

The inferior sagittal sinus (ISS) is a dural venous sinus located within the falx cerebri of the brain.

Inferior salivatory nucleus

The inferior salivatory nucleus (ISN) is a cranial nerve nucleus in the brainstem that is primarily involved in parasympathetic innervation of the parotid gland.

Inferior semilunar (caudal) lobule of posterior lobe of cerebellum

The inferior semilunar lobule (also called the caudal lobule) is a part of the posterior lobe of the cerebellum, specifically within the cerebellar hemisphere.

Inferior tarsus

The inferior tarsus (also called the lower tarsal plate) is a dense connective tissue structure in the lower eyelid that provides structural support and shape.

Inferior temporal gyrus

The inferior temporal gyrus (ITG) is a prominent structure on the lateral surface of the temporal lobe and is important for visual processing and higher cognitive functions.

Inferior temporal line

The inferior temporal line is an important anatomical landmark on the lateral surface of the skull, specifically the temporal bone.

Inferior temporal retinal arteriole and venule

The inferior temporal retinal arteriole and venule are key vessels supplying and draining the inferior temporal quadrant of the retina.

Inferior temporal sulcus

The inferior temporal sulcus (ITS) is a prominent sulcus on the lateral surface of the temporal lobe that separates the middle temporal gyrus from the inferior temporal gyrus.

Inferior thalamostriate veins

The inferior thalamostriate veins are small but important veins in the deep cerebral venous system, draining parts of the thalamus and basal ganglia.

Inferior thyroid artery

The inferior thyroid artery (ITA) is a major branch of the thyrocervical trunk that supplies the thyroid gland and nearby neck structures.

Inferior thyroid veins

The inferior thyroid veins are key veins responsible for draining the thyroid gland, particularly its posterior and inferior portions, into the systemic venous circulation.

Inferior vermian artery

The inferior vermian artery is a small but important vessel supplying the inferior portion of the cerebellar vermis.

Inferior vermian vein

The inferior vermian vein is a venous structure that drains the inferior portion of the cerebellar vermis.

Inferior vermis

The inferior vermis is the lower portion of the cerebellar vermis, which is the midline structure connecting the two cerebellar hemispheres. It is part of the posterior and flocculonodular lobes of the cerebellum.

Inferior vestibular nuclei

The inferior vestibular nuclei (IVN) are part of the vestibular nuclear complex in the brainstem, playing a critical role in balance, posture, and eye movements.

Infrahyoid muscles

The infrahyoid muscles are a group of four muscles in the anterior neck located below the hyoid bone. They are also called the “strap muscles” because of their long, flat shape. Their main role is to depress and stabilize the hyoid bone and larynx, which is important for swallowing, speech, and coordinated movement of the mouth and tongue.

Infrahyoid fascia

The infrahyoid fascia is a layer of deep cervical fascia that surrounds the infrahyoid muscles in the anterior neck. It plays an important role in structural organization, compartmentalization, and movement of the neck structures.

Infraorbital artery

The infraorbital artery is a branch of the maxillary artery (a terminal branch of the external carotid artery) that supplies the midface, orbit, and upper teeth.

Infraorbital foramen

The infraorbital foramen is an important opening in the maxilla that allows passage of the infraorbital nerve and artery from the infraorbital canal to the face.

Infraorbital foramen of maxilla

The infraorbital foramen of the maxilla is a key anatomical opening on the anterior surface of the maxilla that allows passage of neurovascular structures from the infraorbital canal to the face.

Infraorbital groove

The infraorbital groove is a bony feature of the orbit that forms the initial part of the infraorbital canal, through which the infraorbital nerve, artery, and vein pass.

Infraorbital margin

The infraorbital margin is the lower boundary of the orbit and serves as an important anatomical landmark for the eye and midface.

Infraorbital nerve (V2)

The infraorbital nerve is a branch of the maxillary division (V2) of the trigeminal nerve (cranial nerve V). It provides sensory innervation to the midface.

Infraorbital nerve entering infraorbital canal

The infraorbital nerve enters the infraorbital canal as part of its course from the pterygopalatine fossa to the face.

Infraorbital nerve of maxillary nerve

The infraorbital nerve is a branch of the maxillary nerve (V2), which is the second division of the trigeminal nerve (cranial nerve V). It is a purely sensory nerve supplying the midface.

Infraorbital recesses of maxillary sinus

The infraorbital recesses of the maxillary sinus refer to the superior extensions of the maxillary sinus that extend toward the floor of the orbit. They are important in both anatomy and clinical practice, particularly in sinus surgery.

Infraorbital vein

The infraorbital vein is a venous structure that accompanies the infraorbital artery and nerve along the floor of the orbit and the anterior maxilla. It is part of the facial and orbital venous drainage system.

Infratemporal crest of sphenoid bone

The infratemporal crest is a bony landmark on the sphenoid bone that separates the temporal and infratemporal surfaces of the greater wing.

Infratemporal fossa

The infratemporal fossa is a deep anatomical space located below and deep to the zygomatic arch and posterior to the maxilla. It contains important muscles, vessels, and nerves involved in mastication, facial sensation, and blood supply.

Infratemporal surface of maxilla

The infratemporal surface of the maxilla is the posterior aspect of the body of the maxilla that contributes to the anterior boundary of the infratemporal fossa.

Infratrochlear nerve

The infratrochlear nerve is a sensory branch of the nasociliary nerve, which itself is a branch of the ophthalmic division (V1) of the trigeminal nerve (cranial nerve V). It supplies the medial region of the orbit and upper nose.

Infratrochlear nerve (from nasociliary nerve)

Infratrochlear nerve of ophthalmic nerve

Infundibular process

The infundibular process is an anatomical structure related to the ethmoid and frontal sinuses, often mentioned in sinus anatomy.

Infundibular stem

The infundibular stem refers to the narrow channel or stalk-like portion of the ethmoidal infundibulum that connects the frontal sinus and anterior ethmoidal air cells to the middle meatus of the nasal cavity. It is an important landmark in sinonasal anatomy and endoscopic sinus surgery.

Infundibulum (pituitary stalk)

The infundibulum, in the context of the pituitary gland, is commonly referred to as the pituitary stalk. It is the thin funnel-shaped structure connecting the hypothalamus to the pituitary gland, allowing both neural and vascular communication.

Infundibulum leading to frontonasal canal

The infundibulum leading to the frontonasal canal refers to the bony and mucosal passage connecting the frontal sinus to the nasal cavity via the frontonasal duct. This structure is a key component of frontal sinus drainage.

Inner hair cell

Inner hair cells (IHCs) are specialized sensory cells in the cochlea that play a crucial role in hearing by converting mechanical sound vibrations into neural signals. They are the primary transducers for auditory information.

Insertion of levator palpebrae superioris muscle

The levator palpebrae superioris (LPS) muscle is the primary elevator of the upper eyelid. Its insertion is key to its function in raising the eyelid.

Insertion of masseter muscle

The masseter muscle is one of the primary muscles of mastication, responsible for elevating the mandible (closing the jaw). Its insertion determines its leverage and effectiveness in chewing.

Insertion of temporalis muscle to coronoid process of mandible

The temporalis muscle is a major muscle of mastication, responsible for elevating and retracting the mandible. Its insertion on the coronoid process is key for its function.

Inspection of oral cavity

Inspection of the oral cavity is the first step in oral examination, allowing assessment of the lips, teeth, gums, tongue, palate, and oropharynx for abnormalities. A systematic approach is key to detect infection, trauma, tumors, or developmental anomalies.

Insula (island of Reil)

The insula, also known as the island of Reil, is a region of the cerebral cortex buried within the lateral sulcus (Sylvian fissure). It is involved in multimodal processing including sensory, autonomic, emotional, and gustatory functions.

Interalveolar septa

The interalveolar septa are the thin bony partitions that separate adjacent alveoli (tooth sockets) in the maxilla and mandible. They are key components of the alveolar process and provide support and stability for teeth.

Interarticular part

The term “interarticular part” generally refers to the portion of a joint that lies between articulating surfaces, often describing structures that connect or separate two joint surfaces. Its specific meaning depends on the joint context, such as the temporomandibular joint (TMJ), knee, or other synovial joints.

Interarytenoid notch

The interarytenoid notch is an anatomical feature of the larynx, specifically related to the arytenoid cartilages. It plays a role in vocal fold movement and laryngeal structure.

Intercalated node

The intercalated node is a small, specialized component of the cardiac conduction system that plays a key role in propagating electrical impulses through the atrioventricular (AV) conduction pathway.

Interdigitating fibers of levator veli palatini muscle

The interdigitating fibers of the levator veli palatini (LVP) muscle refer to the portion of this muscle that intertwines or overlaps with fibers of the contralateral LVP or nearby muscles in the soft palate, contributing to palatal elevation and closure of the nasopharynx during swallowing and speech.

Interglobular spaces

The interglobular spaces are anatomical features found in developing teeth, specifically within the dentin of the tooth crown. They represent areas of hypomineralized or unmineralized dentin that occur during dentin formation.

Intermaxillary suture

The intermaxillary suture is a fibrous joint (suture) that connects the two maxillary bones at the midline of the upper jaw. It is important in facial growth, orthodontics, and craniofacial anatomy.

Intermediate digastric tendon

The intermediate tendon of the digastric muscle is a key anatomical structure connecting the anterior and posterior bellies of the digastric muscle, allowing coordinated movement of the mandible and hyoid bone.

Intermediate medial frontal branches

The intermediate medial frontal branches are branches of the anterior cerebral artery (ACA) that supply parts of the medial frontal cortex of the brain. These branches are important for motor, cognitive, and executive functions.

Intermediate nerve

The intermediate nerve (also called the nervus intermedius) is a component of the facial nerve (cranial nerve VII) that carries sensory and parasympathetic fibers. It is distinct from the motor component of the facial nerve.

Intermediate tendon of digastric muscle

The intermediate tendon of the digastric muscle is a tendinous connection between the anterior and posterior bellies of the digastric muscle, allowing coordinated movement of the mandible and hyoid bone. It is a key anatomical feature in floor-of-mouth and neck anatomy.

Internal acoustic meatus

The internal acoustic meatus (IAM), also called the internal auditory canal, is a bony canal in the petrous part of the temporal bone that transmits cranial nerves and vessels to the inner ear.

Internal acoustic opening

The internal acoustic opening is another term for the internal acoustic meatus (IAM) or internal auditory canal, the bony canal in the petrous part of the temporal bone that transmits cranial nerves and vessels to the inner ear.

Internal and external branches of superior laryngeal nerve (X)

The superior laryngeal nerve (SLN) is a branch of the vagus nerve (cranial nerve X). It splits into internal and external branches, each with distinct anatomical courses and functions.

Internal branch of superior laryngeal nerve

The internal branch of the superior laryngeal nerve (SLN) is a sensory branch of the vagus nerve (cranial nerve X) that provides innervation to the laryngeal mucosa above the vocal folds and nearby regions.

Internal capsule

The internal capsule is a white matter structure in the brain consisting of ascending and descending fibers that connect the cerebral cortex with subcortical structures. It is a major conduit for motor and sensory information.

Internal carotid artery

The internal carotid artery (ICA) is a major paired artery that supplies blood to the brain, eyes, and some intracranial structures. It is one of the two terminal branches of the common carotid artery, the other being the external carotid artery.

Internal carotid artery and its mingohypophyseal trunk

The internal carotid artery (ICA) is a major artery supplying the brain, and the mingohypophyseal (more commonly called the “meningohypophyseal”) trunk is a small branch arising from the cavernous segment of the ICA, supplying parts of the dura mater and pituitary region.

Internal carotid artery and nerve plexus

The internal carotid artery (ICA) and its nerve plexus form an important neurovascular complex in the neck and cranial cavity. The nerve plexus around the ICA carries sympathetic fibers that distribute to the head and orbit.

Internal carotid artery entering carotid canal

The internal carotid artery (ICA) entering the carotid canal marks the transition of the artery from the neck into the temporal bone, allowing it to reach the cranial cavity. This is an important anatomical landmark for neurovascular and skull base anatomy.

Internal carotid artery of carotid canal

The internal carotid artery (ICA) within the carotid canal refers to its petrous segment as it passes through the temporal bone. This segment is crucial for the transition of the ICA from the neck to the intracranial cavity.

Internal carotid nerve

The internal carotid nerve is part of the sympathetic nervous system and forms the internal carotid plexus around the internal carotid artery (ICA). It plays a key role in head and orbital sympathetic innervation.

Internal carotid plexus

The internal carotid plexus is a network of sympathetic nerve fibers that surrounds the internal carotid artery (ICA) as it ascends from the neck into the cranial cavity. It is a major pathway for sympathetic innervation of the head and orbit.

Internal cerebral vein

The internal cerebral veins are paired deep veins of the brain that drain blood from the deep structures of the cerebral hemispheres and channel it into the great cerebral vein (vein of Galen).

Internal cerebral veins

The internal cerebral veins (ICVs) are paired deep veins of the brain that drain blood from the deep cerebral structures and unite to form the great cerebral vein (vein of Galen).

Internal craniocervical ligaments

The internal craniocervical ligaments are a group of intrinsic ligaments within the craniovertebral junction that stabilize the skull on the cervical spine and control movement between the occiput, atlas (C1), and axis (C2). These ligaments are deep, in contrast to the external (superficial) craniocervical ligaments.

Internal genu of facial nerve

The internal genu of the facial nerve is a bend or “knee” within the facial canal where the facial nerve (cranial nerve VII) changes direction inside the temporal bone. It is an important landmark in temporal bone anatomy and facial nerve pathology.

Internal jugular vein

The internal jugular vein (IJV) is a major venous channel of the neck that drains blood from the brain, face, and neck into the brachiocephalic vein, ultimately reaching the superior vena cava.

Internal medullary lamina

The internal medullary lamina (IML) is a Y-shaped sheet of myelinated fibers within the thalamus of the brain. It essentially acts as a structural and functional divider of the thalamus into different nuclear groups.

Internal nasal branches of infraorbital nerve (V2)

The internal nasal branches of the infraorbital nerve are small sensory branches of the infraorbital nerve, which itself is a continuation of the maxillary nerve (V2), the second division of the trigeminal nerve.

Internal nasal branches of ophthalmic nerve

The internal nasal branches of the ophthalmic nerve are sensory branches of the ophthalmic division (V1) of the trigeminal nerve that supply parts of the nasal cavity.

Internal occipital crest of occipital bone

The internal occipital crest is a ridge on the inner (internal) surface of the occipital bone inside the skull. It runs downward from the internal occipital protuberance toward the foramen magnum in the posterior cranial fossa.

Internal occipital protuberance of occipital bone

The internal occipital protuberance is a bony prominence on the inner (internal) surface of the occipital bone at the back of the skull.

Internal occipital vein

The internal occipital vein is a vein on the inner surface of the occipital bone that helps drain blood from the posterior cranial fossa.

Internal opening of vestibular aqueduct (for endolymphatic duct)

The internal opening of the vestibular aqueduct is an anatomical feature of the temporal bone that serves as the entry point for the endolymphatic duct inside the cranial cavity.

Internal sheath of optic nerve (pia-arachnoid mater)

The internal sheath of the optic nerve refers to the layer of meninges that closely surrounds the optic nerve itself, primarily composed of pia mater and arachnoid mater.

Internal thoracic (mammary) artery

The internal thoracic artery (also called the internal mammary artery) is a major artery of the anterior thoracic wall and is important both surgically and clinically.

Internal thoracic artery

The internal thoracic artery (also called the internal mammary artery) is a key artery supplying the anterior thoracic wall and upper abdominal wall.

Internal thoracic vein

The internal thoracic vein is the venous counterpart of the internal thoracic (mammary) artery, draining the anterior thoracic wall, breasts, and upper abdominal wall into the central venous system.

Interpeduncular cistern

The interpeduncular cistern is an important subarachnoid cistern located in the basal part of the brain, around the midbrain.

Interproximal spaces

The interproximal spaces are anatomical spaces in the dentition and periodontium located between adjacent teeth.

Interthalamic adhesion

The interthalamic adhesion (also called the massa intermedia) is a small midline structure in the diencephalon that connects the two thalami across the third ventricle.

Intertragic notch

The intertragic notch is a small depression or notch in the external ear (auricle) located between the tragus and the antitragus.

Interventricular foramen

The interventricular foramen, also called the foramen of Monro, is a narrow passage that connects each lateral ventricle of the brain to the third ventricle.

Intervertebral disc

The intervertebral disc is a fibrocartilaginous structure situated between adjacent vertebrae in the spine, providing shock absorption, flexibility, and stability.

Intervertebral discs (C2-3 and C3-4)

The intervertebral discs at C2–C3 and C3–C4 are fibrocartilaginous structures located between the vertebral bodies in the cervical spine, providing shock absorption, flexibility, and stability in the neck.

Intervertebral foramen

The intervertebral foramen (also called the neural foramen) is an anatomical opening between adjacent vertebrae through which spinal nerves and blood vessels pass.

Intervertebral foramen (for C3 spinal nerve)

The intervertebral foramen for the C3 spinal nerve is the specific opening through which the third cervical spinal nerve (C3) exits the vertebral canal.

Intervertebral foramen (for C7 spinal nerve)

The intervertebral foramen for the C7 spinal nerve is the lateral opening between the C6 and C7 vertebrae through which the C7 spinal nerve exits the spinal canal.

Intervertebral foramina for spinal nerves

The intervertebral foramina (plural of foramen) are the lateral openings between adjacent vertebrae through which the spinal nerves and associated vessels exit the vertebral canal.

Intervertebral veins

The intervertebral veins are veins associated with the vertebral column that provide venous drainage of the spinal cord, vertebrae, and surrounding structures.

Intraculminate vein

The intraculminate vein is a vein located within the culmen of the superior cerebellar vermis.

Intralaminar nuclei

The intralaminar nuclei are a group of nuclei located within the internal medullary lamina of the thalamus. They play a key role in arousal, attention, and motor functions.

Intraparietal sulcus

The intraparietal sulcus (IPS) is a prominent groove on the lateral surface of the parietal lobe of the brain, playing a key role in visuomotor coordination, attention, and numerical processing.

Internal branch of superior laryngeal nerve

The internal branch of the superior laryngeal nerve (IBSLN) is a sensory branch of the vagus nerve (cranial nerve X) that provides innervation to the larynx and pharynx.

Intrinsic arteries and veins of eye

The intrinsic arteries and veins of the eye are the blood vessels that supply and drain the internal structures of the eyeball, particularly the uvea (iris, ciliary body, and choroid).

Intrinsic muscle

An intrinsic muscle is a muscle located entirely within a specific organ or body part, with both its origin and insertion within that same structure, allowing fine or precise movements.

Intrinsic muscles of larynx

The intrinsic muscles of the larynx are muscles entirely contained within the larynx, meaning both their origin and insertion are on laryngeal cartilages. They are primarily responsible for voice production, controlling pitch, and regulating the size of the rima glottidis.

Intrinsic muscles of tongue

The intrinsic muscles of the tongue are muscles entirely contained within the tongue, meaning both their origin and insertion are within the tongue itself. They are primarily responsible for altering the shape of the tongue for speech, swallowing, and manipulation of food.

Investing layer of (deep) cervical fascia

The investing layer of the deep cervical fascia is the most superficial part of the deep cervical fascia that encloses the entire neck, providing structural support and compartmentalization.

Incisive canal of maxilla

The incisive canal of the maxilla (also called the nasopalatine canal) is a small bony passage in the anterior part of the maxilla that connects the nasal cavity to the oral cavity.

Iridocorneal angle

The iridocorneal angle (also called the anterior chamber angle) is a critical anatomical structure in the anterior chamber of the eye, involved in aqueous humor drainage and intraocular pressure regulation.

Iris

The iris is the colored, circular structure of the eye that controls the size of the pupil, regulating the amount of light entering the eye. It lies in the anterior portion of the uvea between the cornea and lens.

Isthmus of cingulate gyrus

The isthmus of the cingulate gyrus is a narrow, posterior part of the cingulate gyrus that connects it to the parahippocampal gyrus around the splenium of the corpus callosum.

Isthmus of thyroid gland

The isthmus of the thyroid gland is the thin, central portion of the thyroid that connects its two lateral lobes across the midline of the neck.

Joint capsule

A joint capsule (also called an articular capsule) is a fibrous structure that encloses a synovial joint, providing stability, containment of synovial fluid, and protection.

Jugular foramen

The jugular foramen is a large, irregular opening in the base of the skull that serves as a passageway for cranial nerves and venous structures.

Jugular foramen of occipital bone

The jugular foramen of the occipital bone is the portion of the jugular foramen that is formed partly by the occipital bone, as the foramen itself is a joint opening between the temporal and occipital bones.

Jugular fossa of temporal bone

The jugular fossa is a depression in the posterior part of the temporal bone that forms the superior opening of the internal jugular vein at the skull base.

Jugular notch

The jugular notch (also called the suprasternal notch) is a visible and palpable anatomical landmark at the superior border of the manubrium of the sternum.

Jugular process of occipital bone

The jugular process of the occipital bone is a bony projection on the lateral part of the occipital bone that forms part of the jugular foramen and serves as an attachment site for ligaments and muscles.

Jugular trunk

The jugular trunk is a major lymphatic vessel that collects lymph from the head and neck and drains it into the thoracic duct or right lymphatic duct.

Jugulodigastric node

The jugulodigastric lymph node is one of the deep cervical lymph nodes and is a key drainage node for the head and neck, especially the tonsillar region.

Juguloomohyoid node

The juguloomohyoid lymph node is a deep cervical lymph node that is part of the inferior chain of deep cervical nodes and is important in lymphatic drainage of the tongue.

Jugum of body of sphenoid bone

The jugum of the body of the sphenoid bone is a flattened, smooth bony area on the anterior-superior aspect of the sphenoid body, forming part of the floor of the anterior cranial fossa.

Junctions of suprachoroidal tributaries forming vorticose vein

The vorticose (or vortex) veins are the major venous drainage channels of the choroid in the eye, formed by the convergence of suprachoroidal venous tributaries.

Keratinized tip of papilla

The keratinized tip of a papilla refers to the apical portion of a mucosal or dermal papilla that is covered by keratinized epithelium, providing mechanical protection and sometimes enhancing sensory or functional properties.

Labrynthine (internal acoustic) artery

The labyrinthine artery, also called the internal auditory artery, is a small but vital artery that supplies the inner ear, including the cochlea and vestibular apparatus.

Labyrinthine artery

The labyrinthine artery (also called the internal auditory artery) is a critical artery supplying the inner ear, including both cochlear and vestibular structures.

Labyrinthine artery of internal acoustic meatus

The labyrinthine artery of the internal acoustic (auditory) meatus is the small but essential artery that supplies the inner ear structures and travels through the internal auditory canal alongside cranial nerves VII and VIII.

Lacrimal apparatus

The lacrimal apparatus is the system responsible for the production, distribution, and drainage of tears, essential for ocular lubrication, protection, and nutrition of the cornea.

Lacrimal artery

The lacrimal artery is a branch of the ophthalmic artery that supplies the lacrimal gland, lateral eyelids, and adjacent orbital structures.

Lacrimal bone

The lacrimal bone is a small, thin bone in the medial wall of the orbit that contributes to the structure of the eye socket and lacrimal apparatus.

Lacrimal canaliculi

The lacrimal canaliculi are tiny tubes in the eye that drain tears from the surface of the eye into the lacrimal sac.

Lacrimal caruncle

The lacrimal caruncle is a small, fleshy structure in the eye, located at the medial corner (medial canthus).

Lacrimal caruncle in lacrimal lake (lacus lacrimalis)

The lacrimal caruncle in the lacrimal lake (lacus lacrimalis) refers to the small, fleshy structure that sits within the lacrimal lake, the tiny pool of tears at the medial corner of the eye.

Lacrimal gland

The lacrimal gland is the main gland in the eye that produces tears. It is essential for keeping the eye surface moist, nourishing the cornea, and helping protect the eye from dust and microbes.

Lacrimal nerve

The lacrimal nerve is a small sensory nerve that supplies part of the eye and surrounding structures.

Lacrimal nerve of ophthalmic nerve (V1)

The lacrimal nerve is a branch of the ophthalmic nerve (V1), which itself is the first division of the trigeminal nerve (cranial nerve V). It plays an important role in sensation and tear secretion.

Lacrimal sac

The lacrimal sac is a key structure in the tear drainage system, located in the medial part of the orbit.

Lambda

In anatomy, the term “lambda” refers to a specific landmark on the skull.

Lambdoid suture

The lambdoid suture is a fibrous joint on the posterior part of the skull that connects the occipital bone with the two parietal bones.

Lambdoid suture of temporal bone

The lambdoid suture of the temporal bone is not a separate suture of the temporal bone itself—it refers to the portion of the lambdoid suture where it articulates with the temporal bone.

Lamina

In anatomy, the term “lamina” generally refers to a thin, flat layer or plate of bone or tissue. Its specific meaning depends on the structure or region of the body.

Lamina affixa

The lamina affixa is a specific anatomical structure in the brain, particularly related to the lateral ventricle.

Lamina cribrosa of sclera

The lamina cribrosa of the sclera is a specialized structure in the posterior part of the eyeball that serves as a passageway for the optic nerve fibers.

Lamina of cricoid cartilage

The lamina of the cricoid cartilage is a major part of the cricoid cartilage, which is an essential structure of the larynx.

Lamina of thyroid cartilage

The lamina of the thyroid cartilage is a major component of the thyroid cartilage, the largest cartilage of the larynx.

Lamina propria

The lamina propria is a layer of tissue found beneath the epithelium in mucous membranes throughout the body. It is part of the mucosa and plays important structural and functional roles.

Lamina propria of gingiva (gum) (mandibular or maxillary periosteum)

The lamina propria of the gingiva (gum) is the connective tissue layer that lies beneath the oral epithelium and attaches the gingiva to the underlying periosteum of the alveolar bone (mandible or maxilla).

Lamina terminalis

The lamina terminalis is an important structure in the brain, especially in relation to the third ventricle and cerebrospinal fluid (CSF) circulation.

Laryngeal inlet (aditus)

The laryngeal inlet, also called the aditus laryngis, is the opening that connects the larynx with the pharynx.

Laryngeal prominence

The laryngeal prominence is a prominent anatomical feature of the thyroid cartilage in the larynx.

Laryngopharyngeal sympathetic branch

The laryngopharyngeal sympathetic branch is a nerve branch that carries sympathetic fibers to the larynx and pharynx.

Laryngopharynx

The laryngopharynx is the lower part of the pharynx that connects the oral and nasal cavities to the esophagus and larynx.

Larynx

The larynx is a crucial structure in the neck and respiratory system, often referred to as the voice box.

Lateral (marginal) branch

The term “lateral (marginal) branch” can refer to different anatomical structures depending on the context, but generally, it denotes a branch of a nerve, artery, or vein that runs along the lateral or marginal aspect of a structure.

Lateral (temporomandibular) ligament

The lateral (temporomandibular) ligament is an important ligament of the temporomandibular joint (TMJ), providing lateral support and stability.

Lateral (venous) lacuna

The lateral (venous) lacuna is a structure associated with the dural venous sinuses of the brain.

Lateral and medial geniculate bodies of left thalamus

The lateral and medial geniculate bodies are nuclei of the thalamus involved in sensory processing, specifically vision and hearing.

Lateral and medial posterior superior nasal branches in pterygopalatine fossa

The lateral and medial posterior superior nasal branches are branches of the pterygopalatine (sphenopalatine) ganglion, associated with the maxillary nerve (V2) in the pterygopalatine fossa.

Lateral and median apertures of 4th ventricle

The lateral and median apertures of the 4th ventricle are openings that allow cerebrospinal fluid (CSF) to flow from the ventricular system into the subarachnoid space.

Lateral aperture (foramen of Luschka)

The lateral aperture of the 4th ventricle, also called the foramen of Luschka, is a key structure in cerebrospinal fluid (CSF) circulation.

Lateral atlantoaxial joint

The lateral atlantoaxial joint is one of the three synovial joints that form the atlantoaxial articulation between the atlas (C1) and axis (C2) vertebrae.

Lateral branch of supraorbital nerve

The lateral branch of the supraorbital nerve is a sensory nerve that supplies part of the forehead and scalp.

Lateral cerebral sulcus

The lateral cerebral sulcus is a major landmark of the cerebral cortex, also known as the Sylvian fissure.

Lateral cricoarytenoid muscle

The lateral cricoarytenoid muscle is an intrinsic muscle of the larynx that plays a key role in voice production and airway protection.

Lateral cricothyroid ligament

The lateral cricothyroid ligament is a component of the cricothyroid membrane complex, important for laryngeal stability and surgical access.

Lateral crus of major alar cartilage

The lateral crus of the major alar cartilage is an important anatomical structure in the external nose, contributing to the shape and function of the nostrils.

Lateral direct vein

The term “lateral direct vein” is usually encountered in cerebral venous anatomy, particularly as a tributary of the dural venous sinuses.

Lateral dorsal

The term “lateral dorsal” can refer to different structures depending on the context (nerve, muscle, thalamic nucleus, etc.), but it generally indicates a structure located laterally and toward the dorsal (posterior) aspect of an organ or body region.

Lateral frontobasal (orbitofrontal) artery

The lateral frontobasal artery, also called the lateral orbitofrontal artery, is a branch of the anterior cerebral artery (ACA) that supplies the orbitofrontal region of the frontal lobe.

Lateral funiculus

The lateral funiculus is an important part of the spinal cord white matter that contains ascending sensory and descending motor pathways.

Lateral geniculate bodies

The lateral geniculate bodies (LGBs) are paired thalamic nuclei that serve as the primary relay centers for visual information from the retina to the visual cortex.

Lateral glossoepiglottic fold

The lateral glossoepiglottic fold is a mucosal fold in the oropharynx that connects the side of the epiglottis to the lateral margins of the tongue.

Lateral hypothalamic area

The lateral hypothalamic area (LHA) is a major functional region of the hypothalamus involved in feeding, arousal, reward, and autonomic regulation. It is not a sharply defined nucleus but a large zone containing several intermixed cell groups and fiber pathways.

Lateral internal nasal branch of anterior ethmoidal nerve (V1)

The lateral internal nasal branch of the anterior ethmoidal nerve is a sensory branch of the ophthalmic division of the trigeminal nerve (V1). It supplies part of the anterosuperior nasal cavity, specifically the lateral wall.

Lateral lamina of cartilage

The term “lateral lamina of cartilage” most commonly refers to the lateral lamina of the cartilaginous (pharyngotympanic) auditory tube — the cartilage of the Eustachian tube.

Lateral lamina of cartilaginous part of auditory (pharyngotympanic, Eustachian) tube

The lateral lamina is the smaller, lateral plate of elastic cartilage that forms part of the cartilaginous portion of the auditory (Eustachian) tube.

It lies lateral to the larger medial lamina, and together the two laminae create the incomplete, gutter-shaped cartilage that supports the upper and medial walls of the tube.

Lateral ligament of temporomandibular joint

The lateral ligament of the temporomandibular joint (TMJ)—also called the temporomandibular ligament—is the primary intrinsic ligament that reinforces the TMJ capsule laterally.

Lateral masses of atlas

The term “lateral mass” most commonly refers to the lateral mass of the atlas (C1 vertebra), but it is also used in other contexts (cervical vertebrae, sacrum).

Lateral membranous ampulla

The lateral membranous ampulla refers to the ampulla of the lateral (horizontal) semicircular duct—the enlarged, sensory-containing end of the lateral semicircular duct within the membranous labyrinth of the inner ear.

Lateral mesencephalic vein

The lateral mesencephalic vein is one of the major superficial veins of the midbrain (mesencephalon). It drains blood from the lateral surface of the midbrain and serves as an important channel connecting deep and superficial venous systems.

Lateral nasal artery

The lateral nasal artery is a branch of the facial artery that supplies the external nose and nearby structures. It is a key artery in nasal vascularization and an important landmark in facial and rhinologic surgery.

Lateral occipitotemporal gyrus

The lateral occipitotemporal gyrus is a structure in the temporal and occipital lobes of the brain that is involved in visual processing, object recognition, and face perception. It is also commonly referred to as the fusiform gyrus in many anatomical texts.

Lateral olfactory stria

The lateral olfactory stria is one of the two primary pathways through which olfactory information is transmitted from the olfactory bulb to the cerebral cortex.

Lateral olfactory tract nucleus

The term “lateral olfactory tract nucleus” usually refers to the cortical target nuclei of the lateral olfactory tract, i.e., the structures in the brain that receive input from the lateral olfactory stria. These are sometimes collectively called the primary olfactory (piriform) cortical nuclei.

Lateral palpebral artery

The lateral palpebral artery is a branch of the ophthalmic artery that supplies the lateral portion of the eyelids. It forms part of the vascular network that maintains perfusion of the eyelids and contributes to arterial arcades.

Lateral palpebral ligament and overlying raphe

The lateral palpebral ligament and its overlying raphe are important anatomical structures that stabilize the eyelids at the lateral canthus and serve as attachment points for the orbicularis oculi muscle.

Lateral plate of pterygoid process of sphenoid bone

The lateral plate of the pterygoid process is one of the two plates (lateral and medial) of the pterygoid process of the sphenoid bone, forming part of the posterior floor of the nasal cavity and the pterygoid fossa. It has important muscular and neurovascular attachments.

Lateral posterior

The term by itself is directional in anatomy, meaning toward the side (lateral) and toward the back (posterior).

Lateral process of malleus

The lateral process of the malleus is a small but important bony projection of the malleus, one of the three ossicles of the middle ear. It serves as a point of attachment for the tympanic membrane and helps transmit sound vibrations.

Lateral process of nasal septal cartilage

The lateral process of the nasal septal cartilage is a small anatomical extension of the septal cartilage that helps form part of the lateral wall of the nasal cavity and contributes to the structural framework of the nose.

Lateral process of septal nasal cartilage

The lateral process of the septal nasal cartilage is a small but important part of the nasal septum’s quadrangular cartilage that contributes to the lateral wall of the nasal cavity and supports the upper lateral cartilages.

Lateral pterygoid

The lateral pterygoid is one of the muscles of mastication, located in the infratemporal fossa, and is unique among the jaw muscles because its primary function is to protract the mandible and assist in lateral movements rather than simply elevating the jaw.

Lateral pterygoid artery

The lateral pterygoid artery is a branch of the maxillary artery that supplies the lateral pterygoid muscle and adjacent infratemporal structures. It is part of the pterygoid portion of the maxillary artery.

Lateral pterygoid muscle

The lateral pterygoid muscle is a muscle of mastication in the infratemporal fossa that is unique among the jaw muscles because its primary action is to protract and laterally move the mandible, rather than just elevate it. It also plays a key role in guiding the temporomandibular joint (TMJ) disc during movement.

Lateral pterygoid nerve of mandibular nerve

The lateral pterygoid nerve is the motor nerve branch that innervates the lateral pterygoid muscle, which is one of the muscles of mastication. It is a branch of the mandibular nerve (V3), the third division of the trigeminal nerve.

Lateral pterygoid plate

The lateral pterygoid plate is one of the two plates of the pterygoid process of the sphenoid bone. It serves as a major origin for the lateral and medial pterygoid muscles, forming part of the infratemporal and pterygoid fossae, and contributes to the structure of the nasal cavity.

Lateral radiograph

A lateral radiograph is a type of X-ray image taken from the side (lateral view) of a body part. It is commonly used in radiology to evaluate bone structures, soft tissues, and airways in profile, providing information that cannot be seen on a frontal (anteroposterior) view.

Lateral recess

The term “lateral recess” can refer to several anatomical spaces depending on the region (brain, sinuses, spine). I’ll cover the most common references in neuroanatomy and sinuses.

Lateral rectus muscle

The lateral rectus muscle is one of the extraocular muscles of the eye. Its primary function is to abduct the eyeball, i.e., move the eye laterally away from the midline.

Lateral semicircular canal

The lateral semicircular canal is one of the three semicircular canals of the inner ear that detect rotational (angular) movements of the head, particularly in the horizontal plane.

Lateral semicircular canal and duct

The lateral semicircular canal and its associated duct are part of the vestibular system in the inner ear, responsible for detecting rotational (angular) movements of the head, particularly in the horizontal plane.

Lateral semicircular canals

The lateral semicircular canals (also called horizontal semicircular canals) are part of the vestibular system of the inner ear, specialized for detecting rotational movements of the head in the horizontal plane.

Lateral semicircular duct

The lateral semicircular duct is the membranous portion of the lateral (horizontal) semicircular canal in the inner ear, part of the vestibular system responsible for detecting horizontal rotational movements of the head.

Lateral sulcus (of Sylvius)

The lateral sulcus, also known as the Sylvian fissure, is a prominent structure of the cerebral cortex that separates major lobes and houses key functional areas.

Lateral vein of lateral ventricle

The lateral vein of the lateral ventricle is part of the deep venous system of the brain, responsible for draining blood from the lateral ventricle region and adjacent deep white matter into larger cerebral veins.

Lateral ventricle

The lateral ventricles are paired cavities within the cerebral hemispheres that are part of the ventricular system of the brain, containing cerebrospinal fluid (CSF) and playing a key role in CSF circulation.

Lateral vestibular nuclei

The lateral vestibular nuclei are part of the vestibular nuclei complex in the brainstem, playing a key role in balance, posture, and coordination of limb movements via the vestibulospinal tract.

Lateral wall of nasal cavity

The lateral wall of the nasal cavity is a complex anatomical structure that contains several important bony and cartilaginous elements, conchae (turbinates), and openings for paranasal sinuses, playing a key role in airflow, filtration, humidification, and drainage.

Left and right greater palatine arteries

The greater palatine arteries are branches of the descending palatine artery, itself a branch of the maxillary artery, that supply the hard palate and adjacent structures. They exist as left and right vessels corresponding to each side of the palate.

Left and right lesser palatine arteries

The lesser palatine arteries are paired branches of the descending palatine artery (from the maxillary artery) that supply the soft palate, tonsils, and uvula. They run alongside the lesser palatine nerves.

Left and right vertebral arteries (intracranial part)

The left and right vertebral arteries are major arteries of the posterior circulation of the brain. Their intracranial parts are the segments within the cranial cavity after entering through the foramen magnum, ultimately forming the basilar artery.

Left anterior cerebral artery

The left anterior cerebral artery (ACA) is a major branch of the internal carotid artery that supplies the medial portions of the frontal lobes and superior medial parietal lobes.

Left brachiocephialic vein

The left brachiocephalic vein is a major vein in the thorax that drains blood from the left upper limb, head, neck, and thorax into the superior vena cava (SVC).

Left common carotid artery

The left common carotid artery (CCA) is a major artery of the head and neck, supplying blood to the left side of the head, neck, and brain.

Left deep cervical vein

The left deep cervical vein is a venous structure in the neck that drains the deep muscles and vertebral structures of the cervical region and communicates with larger veins such as the vertebral and brachiocephalic veins.

Left inferior laryngeal nerve

The left inferior laryngeal nerve is the terminal branch of the left recurrent laryngeal nerve, a branch of the vagus nerve (CN X), and is primarily motor to the intrinsic muscles of the larynx (except cricothyroid) and sensory below the vocal cords.

Left internal carotid artery

The left internal carotid artery (ICA) is a major artery that supplies the brain, eye, and parts of the forehead and nose. It is a continuation of the left common carotid artery and is a key part of the anterior circulation of the brain.

Left internal jugular vein

The left internal jugular vein (IJV) is a major vein of the neck that drains venous blood from the brain, face, and neck and conveys it to the brachiocephalic vein.

Left interventricular foramen (of Monro)

The left interventricular foramen, also known as the foramen of Monro, is a narrow channel connecting the lateral ventricle to the third ventricle on the left side of the brain.

Left labrynthine artery

The left labyrinthine artery is a small but important artery that supplies the inner ear structures, including the cochlea and vestibular apparatus. It is typically a branch of either the anterior inferior cerebellar artery (AICA) or, less commonly, the basilar artery directly.

Left lateral aperture (foramen of Luschka)

The left lateral aperture, also known as the foramen of Luschka, is an important structure in the ventricular system of the brain that allows cerebrospinal fluid (CSF) to exit the fourth ventricle into the subarachnoid space.

Left lateral recess

The left lateral recess refers to a lateral extension of the fourth ventricle in the brain, which is closely associated with the lateral aperture (foramen of Luschka).

Left lateral ventricle

The left lateral ventricle is one of the two paired lateral ventricles in the brain that contain cerebrospinal fluid (CSF) and are part of the ventricular system.

Left lobe of thyroid gland

The left lobe of the thyroid gland is one of the two primary lobes of the thyroid, an endocrine gland located in the anterior neck, responsible for producing thyroid hormones (T3 and T4) and calcitonin (from the parafollicular cells).

Left meningeal artery

The left meningeal artery refers to the arterial supply to the meninges (primarily the dura mater) on the left side of the cranial cavity. The most clinically significant is the left middle meningeal artery, a branch of the maxillary artery, though there are other meningeal arteries (anterior, posterior).

Left middle cerebral artery

The left middle cerebral artery (MCA) is one of the major arteries of the brain and a primary branch of the internal carotid artery, supplying large portions of the lateral cerebral hemisphere.

Left orbit

The left orbit is the bony cavity in the skull that houses and protects the eyeball and its associated structures on the left side.

Left posterior spinal artery

The left posterior spinal artery is one of the two arteries that supply the posterior (dorsal) portion of the spinal cord on the left side. It runs along the back (posterolateral) surface of the spinal cord and provides blood to the posterior columns (which carry touch, vibration, and proprioception signals) and part of the posterior gray matter.

Left pulvinar

The left pulvinar is the posterior portion of the thalamus on the left side of the brain.

Left recurrent laryngeal nerve

The left recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that loops down into the chest before returning upward to the neck to innervate the larynx. It has an important role in voice, swallowing, and airway protection.

Left subclavian artery

The left subclavian artery is a major artery that supplies blood to the left arm, parts of the chest, neck, and brain. It is one of the three main branches of the aortic arch.

Left subclavian vein

The left subclavian vein is a large vein that drains blood from the left upper limb, parts of the neck, and thoracic wall back toward the heart. It runs alongside the left subclavian artery but has some important differences in course and connections.

Left superior and inferior colliculi

The left superior and inferior colliculi are paired structures on the dorsal midbrain, forming part of the tectum. They are involved in processing visual and auditory information and coordinating reflexive movements.

Left thalamus

The left thalamus is the left half of the thalamus, a paired structure located deep within the diencephalon of the brain. It acts as a major relay and processing hub for sensory, motor, and cognitive information.

Left thyrocervical trunk

The left thyrocervical trunk is a short but important artery that arises from the first part of the left subclavian artery and supplies blood to parts of the neck, thyroid gland, and shoulder region.

Left transverse sinus

The left transverse sinus is a major venous channel in the brain that drains blood from the brain toward the internal jugular vein. It is part of the dural venous sinus system, located within the dura mater.

Left uncinate process

The left uncinate process is a hook-shaped bony projection of the left ethmoid bone in the lateral wall of the nasal cavity.

Left vagus nerve (X)

The left vagus nerve is the tenth cranial nerve (cranial nerve X) on the left side, responsible for parasympathetic, motor, and sensory innervation to multiple organs in the head, neck, thorax, and abdomen.

Left vertebral artery

The left vertebral artery is a major artery that supplies blood to the posterior part of the brain, including the brainstem, cerebellum, and posterior cerebral hemispheres. It is one of the two vertebral arteries (left and right) that form the basilar artery.

Left vertebral vein

The left vertebral vein is a vein that runs alongside the vertebral artery in the neck and drains blood from the cervical spinal cord, vertebrae, and posterior neck muscles into the brachiocephalic vein.

Lens

In anatomy, the lens is a transparent, biconvex structure in the eye that helps focus light onto the retina to form clear images. It is located behind the iris and in front of the vitreous body.

Lenticular process of incus

The lenticular process of the incus is a small anatomical feature of the middle ear ossicles, specifically the incus (anvil). It plays an important role in transmitting sound vibrations from the middle ear to the inner ear.

Lentiform nucleus (globus pallidus medial to putamen)

The lentiform nucleus is a lens-shaped structure in the basal ganglia of the brain, and your note specifies its organization: the globus pallidus lies medially, and the putamen lies laterally.

Lesser horn of hyoid bone

The lesser horn of the hyoid bone (also called the lesser cornu) is a small bony projection of the hyoid bone that serves as an attachment point for ligaments and muscles in the neck.

Lesser occipital nerve (C2)

The lesser occipital nerve is a cutaneous branch of the cervical plexus, primarily arising from ventral ramus of C2 (and sometimes C3). It provides sensory innervation to the scalp behind the ear.

Lesser palatine artery

The lesser palatine artery is a branch of the descending palatine artery, which itself arises from the maxillary artery. It supplies blood to the soft palate and surrounding structures.

Lesser palatine foramen

The lesser palatine foramen is a small opening in the palatine bone of the skull that allows the passage of neurovascular structures to the soft palate.

Lesser palatine nerves (V2)

The lesser palatine nerves are branches of the maxillary nerve (V2) that provide sensory innervation to the soft palate, uvula, and palatine tonsil.

Lesser petrosal nerve

The lesser petrosal nerve is a cranial nerve branch that carries preganglionic parasympathetic fibers to the otic ganglion, ultimately innervating the parotid gland.

Lesser petrosal nerve of foramen ovale

The lesser petrosal nerve is a parasympathetic nerve that usually passes through the middle cranial fossa to the otic ganglion, but in some cases it may exit the skull through the foramen ovale. This is an anatomical variation.

Lesser petrosal nerve of mandibular nerve

The lesser petrosal nerve is closely associated with the mandibular nerve (V3) because its postganglionic fibers travel with a branch of V3 to reach the parotid gland.

Lesser wing of sphenoid bone

The lesser wing of the sphenoid bone is a thin, triangular bony projection of the sphenoid bone that forms part of the floor of the anterior cranial fossa and contributes to the orbit.

Levator anguli oris

The levator anguli oris is a facial muscle that helps elevate the corners of the mouth, contributing to smiling.

Levator labii superioris

The levator labii superioris is a facial muscle that raises the upper lip, contributing to facial expressions such as sneering or showing the teeth.

Levator labii superioris alaeque nasi

The levator labii superioris alaeque nasi is a facial muscle that has a dual action: it elevates the upper lip and flares the nostril. Its name literally means “levator of the upper lip and wing of the nose.”

Levator palpebrae superioris muscle

The levator palpebrae superioris (LPS) is a muscle of the upper eyelid responsible for raising the upper eyelid, enabling the eye to open.

Levator palpebrae superioris muscle of oculomotor nerve (III)

The levator palpebrae superioris (LPS) is the eyelid muscle innervated by the oculomotor nerve (cranial nerve III), responsible for raising the upper eyelid.

Levator scapulae muscle

The levator scapulae is a posterior neck and upper back muscle that elevates the scapula and helps in neck movement.

Levator veli palatini muscle

The levator veli palatini is a muscle of the soft palate that plays a key role in swallowing and speech by elevating the soft palate to close off the nasopharynx.

Ligamenta flava

The ligamenta flava (singular: ligamentum flavum) are a pair of yellow elastic ligaments that connect the laminae of adjacent vertebrae in the vertebral column. They play a key role in maintaining spinal stability and posture.

Ligamentum nuchae

The ligamentum nuchae (nuchal ligament) is a midline ligament in the posterior neck that provides support to the head and cervical spine and serves as an attachment site for muscles.

Lipping of vertebral margins

Lipping of vertebral margins refers to the bony overgrowths or small projections at the edges of the vertebral bodies, often seen on imaging or in anatomical studies of the spine. These are sometimes called osteophytes.

Limbs of stapes

The stapes is the smallest bone in the human body, one of the three ossicles of the middle ear, and its limbs (or crura) connect the head of the stapes to the footplate, transmitting sound vibrations to the inner ear.

Limen nasi

The limen nasi is a small anatomical landmark in the nasal cavity that marks the transition between the nasal vestibule and the nasal cavity proper.

Limen of insula (island of Reil)

The limen of the insula is an anatomical landmark in the brain that marks the anterior boundary of the insular cortex, where the insula meets the orbital and temporal opercula.

Lingual artery

The lingual artery is a branch of the external carotid artery that primarily supplies the tongue and floor of the mouth.

Lingual branch of glossopharyngeal nerve

The lingual branch of the glossopharyngeal nerve (CN IX) is a sensory branch that innervates the posterior third of the tongue.

Lingual branches

The term “lingual branches” generally refers to the branches of different cranial or cervical nerves that supply the tongue. These can include both motor and sensory fibers, depending on the nerve of origin.

Lingual glands (serous glands of von Ebner)

The lingual glands, also known as the serous glands of von Ebner, are minor salivary glands located on the tongue that play a role in taste and oral lubrication.

Lingual gyrus

The lingual gyrus is a region of the occipital lobe of the brain involved primarily in visual processing, particularly visual memory and recognition of letters and complex images.

Lingual minor salivary gland

Lingual minor salivary glands are small, scattered salivary glands in the tongue that secrete primarily mucous or mixed saliva to aid in lubrication and protection of the oral cavity.

Lingual nerve (V3)

The lingual nerve is a branch of the mandibular division (V3) of the trigeminal nerve (cranial nerve V). It is a sensory nerve that carries touch, pain, and temperature sensations from the anterior two-thirds of the tongue, the floor of the mouth, and the lingual gingiva (gums on the tongue side of the lower teeth). It also carries taste and parasympathetic fibers from the chorda tympani (a branch of the facial nerve, CN VII), which supply the taste buds of the anterior tongue and the submandibular and sublingual salivary glands.

Lingual tonsil (lingual nodules)

The lingual tonsil (or lingual nodules) is a collection of lymphoid tissue on the posterior part of the tongue, just in front of the epiglottis.

Lingual vein

The lingual vein is a vein that drains blood from the tongue.

Lingula

The term “lingula” refers to a small, tongue-shaped projection in anatomy. Its exact meaning depends on the structure it is associated with.

Lingula of mandible

The lingula of the mandible is a small, tongue-shaped bony projection on the medial (tongue-side) surface of the mandibular ramus, located just anterior to the mandibular foramen.

Lingula of superior vermis

The lingula of the superior vermis is a small, tongue-shaped part of the cerebellum.

Liver

The liver is a large, vital organ in the upper right part of the abdomen that performs many essential functions for metabolism, digestion, and detoxification.

Lobule

In anatomy, a lobule is a small, well-defined subdivision of an organ, often shaped like a tiny lobe. The exact meaning depends on the organ being described.

Lobule of auricle

The lobule of the auricle is the soft, lower part of the external ear—the part most people think of as the “earlobe.”

Locus ceruleus

The locus ceruleus (also spelled locus coeruleus) is a small but very important structure in the brainstem, specifically in the pons.

Long and short ciliary nerves

The long and short ciliary nerves are branches of the ophthalmic division (V1) of the trigeminal nerve and are important for innervating the eye.

Long gyrus of insula (island of Reil)

The long gyrus of the insula, also called the long insular gyrus, is one of the main gyri of the insula (Island of Reil) in the brain.

Long hypophyseal portal veins

The long hypophyseal portal veins are part of the pituitary (hypophyseal) portal system, which connects the hypothalamus to the anterior pituitary (adenohypophysis).

Long limb of incus

The long limb of the incus (also called the long process of the incus) is a part of the incus, one of the three small bones (ossicles) in the middle ear.

Long posterior ciliary artery

The long posterior ciliary arteries are important arteries that supply the eye, particularly the sclera, ciliary body, and anterior uvea.

Longitudinal cerebral fissure

The longitudinal cerebral fissure is a deep groove that separates the two cerebral hemispheres of the brain.

Longitudinal esophageal muscle

The longitudinal esophageal muscle is one of the muscular layers of the esophagus that helps in swallowing and propelling food toward the stomach.

Longitudinal pharyngeal muscles

The longitudinal pharyngeal muscles are a group of muscles in the pharynx that run vertically along its length and play a key role in swallowing by shortening and widening the pharynx.

Longus capitis muscle

The longus capitis is a prevertebral (deep anterior) neck muscle that helps flex the head and neck.

Longus colli muscle

The longus colli is a deep anterior neck muscle that lies on the front of the cervical vertebrae and is important for neck flexion and stability.

Lower 1st molar

The lower first molar (mandibular first molar) is one of the permanent teeth in the lower jaw and plays a key role in chewing and grinding food.

Lower 1st premolar

The lower first premolar (mandibular first premolar) is a permanent tooth in the lower jaw that helps in tearing and grinding food.

Lower 2nd molar

The lower second molar (mandibular second molar) is a permanent tooth in the lower jaw located posterior to the first molar and anterior to the third molar (if present). It plays an important role in grinding food.

Lower 2nd premolar

The lower second premolar (mandibular second premolar) is a permanent tooth in the lower jaw that plays a role in chewing and grinding food.

Lower 3rd molar

The lower third molar (mandibular third molar), commonly called the wisdom tooth, is the last permanent tooth in the lower jaw and often the most variable in shape and eruption.

Lower border of highest nasal concha

The lower border of the highest nasal concha refers to the inferior edge of the supreme (or highest) nasal concha, which is a small, variably present bony projection in the nasal cavity.

Lower border of superior nasal concha

The lower border of the superior nasal concha refers to the inferior edge of the superior nasal concha, a bony structure in the lateral wall of the nasal cavity.

Lower canine

The lower canine (mandibular canine) is a permanent tooth in the lower jaw that plays a key role in tearing food and maintaining dental arch stability.

Lower central incisor

The lower central incisor (mandibular central incisor) is one of the front teeth in the lower jaw and is specialized for cutting food.

Lower lateral incisor

The lower lateral incisor (mandibular lateral incisor) is a permanent tooth in the lower jaw, located just lateral to the central incisors, and is specialized for cutting food.

Lunate sulcus

The lunate sulcus is a shallow groove in the occipital lobe of the brain associated with the visual cortex.

Lungs

The lungs are the primary organs of the respiratory system responsible for gas exchange—taking in oxygen (O₂) and expelling carbon dioxide (CO₂).

Lymph follicles

Lymph follicles are small, spherical structures of lymphoid tissue that are essential components of the immune system, primarily involved in producing immune cells and mounting responses to antigens.

Lymph nodes

Lymph nodes are small, bean-shaped organs of the lymphatic system that function as filters for lymph and hubs of immune activity.

Lymph vessels

Lymph vessels are the network of thin-walled tubes that transport lymph (a clear fluid containing immune cells, proteins, and fats) throughout the body, forming an essential part of the lymphatic system.

Lymphatic drainage of pharynx

The lymphatic drainage of the pharynx is organized by its three main regions: nasopharynx, oropharynx, and laryngopharynx (hypopharynx) and is clinically important for fighting infection spreading and the metastasis of cancers.

Lymphatic drainage of tongue

The lymphatic drainage of the tongue operates in a regional and hierarchical manner, following specific pathways from the tongue tissue to lymph nodes, which is crucial for immune defense and clinically important in cancer metastasis.

Macula

The macula is a specialized region of the retina in the eye responsible for sharp, central vision (high-acuity vision).

Main trunk of facial nerve

The main trunk of the facial nerve refers to the initial segment of cranial nerve VII (facial nerve) after it exits the brainstem, before it divides into its branches.

Major alar cartilage

The major alar cartilage is a key structural component of the nose that shapes and supports the nostrils (nares).

Major arterial cricle of iris

The major arterial circle of the iris is a circular vascular structure in the iris that plays a central role in supplying blood to the iris and ciliary body.

Malleus (head)

The malleus (head) is the upper part of the malleus, one of the three small bones in the middle ear (ossicles) that transmit sound from the eardrum to the inner ear.

Mammillary bodies

The mammillary bodies are small, paired structures in the brain that are part of the limbic system, primarily involved in memory processing.

Mammillary body of principal nuclei of hypothalamus

The mammillary bodies are considered part of the principal (or main) nuclei of the hypothalamus and play a central role in memory and limbic system function.

Mammillothalamic fasciculus

The mammillothalamic fasciculus (also called the tract of Vicq d’Azyr) is a bundle of nerve fibers connecting the mammillary bodies of the hypothalamus to the anterior nuclei of the thalamus.

Mammillothalamic tract

The mammillothalamic tract (also called the tract of Vicq d’Azyr) is a bundle of nerve fibers connecting the mammillary bodies of the hypothalamus to the anterior nuclei of the thalamus, and it is a key component of the limbic system and Papez circuit.

Mandible

The mandible is the lower jawbone and the largest and strongest bone of the face, essential for mastication (chewing), speech, and facial structure.

Mandible (body)

The body of the mandible is the horizontal, central portion of the mandible that forms the lower jaw and supports the lower teeth.

Mandibular canal

The mandibular canal is a bony passage within the mandible that transmits the inferior alveolar neurovascular bundle, playing a crucial role in supplying the lower teeth, chin, and lower lip.

Mandibular division of trigeminal nerve (V3)

The mandibular division of the trigeminal nerve (V3) is the third branch of cranial nerve V (trigeminal nerve). It is unique among the trigeminal divisions because it carries both sensory and motor fibers.

Mandibular foramen

The mandibular foramen is a key opening on the medial surface of the mandible that allows passage of the inferior alveolar neurovascular bundle.

Mandibular fossa

The mandibular fossa is a depression in the temporal bone that forms part of the temporomandibular joint (TMJ), allowing articulation with the mandibular condyle.

Mandibular nerve (V3)

The mandibular nerve is the third division (V3) of the trigeminal nerve (cranial nerve V) and is unique among trigeminal branches because it carries both sensory and motor fibers.

Mandibular nodes

The mandibular nodes are a group of lymph nodes located along the lower jaw (mandible) that are part of the facial and cervical lymphatic system, involved in lymphatic drainage of the face, oral cavity, and associated structures.

Mandibular notch of mandible

The mandibular notch is a curved depression on the superior border of the mandible, located between the coronoid process and the condylar process. It serves as a passageway for muscles and vessels in the jaw region.

Manubrium of sternum

The manubrium of the sternum is the uppermost segment of the sternum, playing a key role in thoracic structure, articulation with clavicles and ribs, and protection of thoracic organs.

Marginal collecting vessels

Marginal collecting vessels are lymphatic vessels located near the edge (margin) of an organ, tissue, or structure that collect lymph from superficial lymphatic capillaries and drain it toward larger lymphatic trunks or regional lymph nodes.

Marginal mandibular branch of facial nerve

The marginal mandibular branch is a branch of the facial nerve (cranial nerve VII) that controls the muscles of the lower lip and chin.

Marginal sulcus

The term “marginal sulcus” usually refers to a groove or depression at the edge (margin) of a structure, but the exact meaning depends on the anatomical context.

Masseter muscle

The masseter muscle is one of the major muscles of mastication (chewing).

Masseteric artery

The masseteric artery is a small branch of the maxillary artery that supplies the masseter muscle.

Masseteric fascia

The masseteric fascia is a layer of connective tissue that covers the masseter muscle.

Masseteric nerve

The masseteric nerve is a motor branch of the mandibular nerve (V3), which is the third division of the trigeminal nerve, cranial nerve V. It is responsible for controlling the masseter muscle, one of the main muscles of mastication.

Mastication

Mastication is the process of chewing food in the mouth to break it down mechanically before swallowing and digestion.

Mastoid air cells

Mastoid air cells are small, air-filled spaces within the mastoid process of the temporal bone that communicate with the middle ear.

Mastoid angle of parietal bone

The mastoid angle of the parietal bone is a specific anatomical part of the parietal bone of the skull.

Mastoid antrum

The mastoid antrum is a large air-filled cavity within the mastoid part of the temporal bone that communicates with the middle ear.

Mastoid branch of occipital artery

The mastoid branch of the occipital artery is a small branch that supplies parts of the posterior cranial structures, particularly near the mastoid region.

Mastoid canaliculus of temporal bone

The mastoid canaliculus is a small bony canal in the temporal bone that transmits a nerve to the middle ear.

Mastoid cells

Mastoid cells, also called mastoid air cells, are small, air-filled spaces within the mastoid process of the temporal bone. They are closely related to the middle ear.

Mastoid emissary vein

The mastoid emissary vein is a venous channel connecting the intracranial venous sinuses with veins outside the skull, specifically near the mastoid process.

Mastoid emissary vein of mastoid foramen

The mastoid emissary vein of the mastoid foramen is essentially the same structure as the mastoid emissary vein, specifically passing through the mastoid foramen of the temporal bone.

Mastoid foramen of temporal bone

The mastoid foramen is a small opening in the posterior part of the temporal bone, near the mastoid process.

Mastoid nodes

The mastoid nodes, also called retroauricular lymph nodes, are a group of small lymph nodes located behind the ear near the mastoid process.

Mastoid notch (for digastric muscle) of temporal bone

The mastoid notch (also called the digastric groove) is a groove on the medial side of the mastoid process of the temporal bone that serves as the attachment site for the digastric muscle.

Mastoid process of temporal bone

The mastoid process is a prominent bony projection of the temporal bone located just behind the ear. It serves as an important anatomical landmark and site for muscle attachments.

Maxilla

The maxilla is a paired bone of the upper jaw in the human skull. It plays a crucial role in the structure and function of the face.

Maxilla (frontal process)

The frontal process of the maxilla is a bony projection of the maxilla that extends upward to articulate with the frontal bone of the skull. It’s one of the key processes of the maxilla that helps form the structure of the midface.

Maxillary artery

The maxillary artery is one of the two terminal branches of the external carotid artery, the other being the superficial temporal artery. It is a major artery supplying deep structures of the face, oral cavity, nasal cavity, and parts of the cranial cavity.

Maxillary bone

The maxillary bone, also called the maxilla, is the paired upper jaw bone of the face. It is a central facial bone that plays key roles in supporting the teeth, forming the orbit, nasal cavity, and hard palate, and shaping the midface.

Maxillary division of trigeminal nerve (V2)

The maxillary division of the trigeminal nerve (V2) is the second branch of the trigeminal nerve (cranial nerve V). It is a purely sensory nerve that supplies the middle third of the face.

Maxillary nerve (V2)

The maxillary nerve is the second branch (V2) of the trigeminal nerve (cranial nerve V). It is a purely sensory nerve that transmits sensation from the middle third of the face.

Maxillary plexus

The maxillary plexus is a network of nerves formed around the maxillary artery in the infratemporal and pterygopalatine regions. It is primarily associated with the maxillary nerve (V2) and the pterygopalatine ganglion.

Maxillary sinus

The maxillary sinus is the largest of the paranasal sinuses and is a pyramidal air-filled cavity located within the body of the maxilla. It is an important anatomical structure for respiration, drainage, and dental considerations.

Maxillary vein

The maxillary vein is a deep vein of the face that primarily drains the pterygoid (infratemporal) region and connects with the venous plexuses of the orbit and cranial cavity. It is closely associated with the maxillary artery.

Medial

In anatomy, “medial” is a directional term that means toward the midline of the body. The midline is an imaginary vertical line that divides the body into left and right halves.

Medial branch of supraorbital nerve

The medial branch of the supraorbital nerve is a sensory nerve that is one of the terminal branches of the supraorbital nerve, which itself is a branch of the ophthalmic division (V1) of the trigeminal nerve (CN V).

Medial branches of dorsal rami of cervical spinal nerves

The medial branches of the dorsal rami of the cervical spinal nerves are small sensory and motor nerve branches that arise from the posterior (dorsal) rami of the cervical spinal nerves. They play an important role in innervating the muscles and skin of the neck and back.

Medial crus of major alar cartilage

The medial crus of the major alar cartilage is a structural component of the nose, specifically part of the lower lateral (alar) cartilages that shape the nostrils and tip of the nose.

Medial eminence

In anatomy, the medial eminence is a term used to describe a prominent, raised area located toward the midline of a structure. It appears in several regions of the body, but most commonly in the brainstem and spinal cord.

Medial frontal branches

The medial frontal branches are branches of the facial or ophthalmic arteries/nerves (depending on context) that supply the medial portion of the forehead and scalp. In anatomy, the term is most commonly used to describe branches of the supraorbital or supratrochlear nerves or arteries.

Medial frontal gyrus

The medial frontal gyrus is a part of the frontal lobe of the brain located on the medial (inner) surface of the hemisphere, near the midline. It is involved in higher cognitive functions and motor control.

Medial frontobasal (orbitofrontal) artery

The medial frontobasal artery, also called the medial orbitofrontal artery, is a branch of the anterior cerebral artery (ACA) that supplies the medial part of the frontal lobe near the base of the brain.

Medial frontobasal artery

The medial frontobasal artery is another name for the medial orbitofrontal artery, a branch of the anterior cerebral artery (ACA) that supplies the medial and orbital surfaces of the frontal lobe.

Medial geniculate bodies

The medial geniculate bodies (MGBs) are paired relay nuclei in the thalamus that are critical for auditory processing. They are part of the auditory pathway, transmitting sound information from the brainstem to the auditory cortex.

Medial internal nasal branch of anterior ethmoidal nerve (V1)

The medial internal nasal branch of the anterior ethmoidal nerve is a sensory branch of the anterior ethmoidal nerve, which itself is a branch of the ophthalmic division (V1) of the trigeminal nerve (cranial nerve V). It provides sensation to the nasal cavity.

Medial lamina of cartilage

The term “medial lamina of cartilage” usually refers to a part of a paired cartilage structure in the nose or larynx, where a lamina is a thin plate or layer of cartilage. The medial lamina is the portion closer to the midline of the body or structure.

Medial lamina of cartilaginous part of auditory (pharyngotympanic, Eustachian) tube

The medial lamina of the cartilaginous part of the auditory tube refers to the inner, midline portion of the fibrocartilaginous framework of the Eustachian tube (also called the pharyngotympanic tube) that connects the middle ear to the nasopharynx.

Medial longitudinal fasciculus

The medial longitudinal fasciculus (MLF) is a paired bundle of nerve fibers in the brainstem that is essential for coordinated eye movements and head-eye coordination. It connects cranial nerve nuclei controlling eye movement and integrates vestibular input.

Medial margin of sternocleidomastoid muscle

The medial margin of the sternocleidomastoid (SCM) muscle refers to the edge of the SCM that is closest to the midline of the neck.

Medial occipital artery

The medial occipital artery is not a commonly mentioned standard artery in most anatomical texts, but based on context, it is typically considered a branch of the occipital artery supplying the medial or central part of the posterior scalp and occipital region.

Medial occipitotemporal gyrus

The medial occipitotemporal gyrus is a part of the temporal lobe of the brain, located on the ventral (inferior) surface, bordering the occipital lobe. It is sometimes referred to as the fusiform gyrus, particularly in human neuroanatomy, although strictly speaking, the fusiform gyrus includes both lateral and medial components.

Medial olfactory stria

The medial olfactory stria is a component of the olfactory pathway in the brain, responsible for transmitting smell information from the olfactory bulb to other brain regions.

Medial palpebral artery

The medial palpebral artery is an important artery supplying the eyelids, particularly near the medial canthus.

Medial palpebral ligament

The medial palpebral ligament is a key fibrous structure of the eyelids that provides medial support and serves as an attachment point for eyelid muscles.

Medial plates of pterygoid process of sphenoid bone

The medial plate of the pterygoid process is a thin, vertical bony plate that is part of the pterygoid process of the sphenoid bone in the skull. It serves as a key structure for muscle attachments and anatomical relationships in the posterior nasal and oral regions.

Medial pterygoid artery

The medial pterygoid artery is a small muscular branch of the maxillary artery that primarily supplies the medial pterygoid muscle, which is one of the muscles of mastication.

Medial pterygoid muscle

The medial pterygoid muscle is one of the muscles of mastication, located in the infratemporal region of the skull. It plays a key role in elevating the mandible and assisting in grinding movements.

Medial pterygoid nerve

The medial pterygoid nerve is a branch of the mandibular nerve (V3), which is the third division of the trigeminal nerve (cranial nerve V). It primarily innervates the medial pterygoid muscle, but it also gives off small branches to nearby muscles.

Medial pterygoid plate

The medial pterygoid plate is a thin, vertical bony plate of the pterygoid process of the sphenoid bone, located in the posterior part of the nasal and oral cavities. It serves as an attachment site for muscles of mastication and the soft palate.

Medial rectus muscle

The medial rectus muscle is one of the extraocular muscles that control eye movement. It is primarily responsible for moving the eyeball medially (toward the nose).

Medial vein of lateral ventricle

The medial vein of the lateral ventricle is one of the deep cerebral veins that drains the medial structures of the lateral ventricle and surrounding brain regions.

Medial vestibular nuclei

The medial vestibular nucleus is one of the four main vestibular nuclei located in the brainstem, specifically in the medulla oblongata and lower pons. It is an essential component of the vestibular system, which controls balance, posture, and eye movements.

Medial wall of nasal cavity

The medial wall of the nasal cavity forms the septum that separates the left and right nasal cavities. It is primarily bony and cartilaginous in composition and is a key structure for supporting nasal airflow and the mucosa.

Medial wall of orbit

The medial wall of the orbit forms the inner boundary of the bony orbit and is the thinnest orbital wall, making it vulnerable to fractures. It separates the orbit from the ethmoid and nasal cavities.

Median aperture (foramen of Magendie)

The median aperture, also known as the foramen of Magendie, is one of the key openings in the fourth ventricle of the brain that allows cerebrospinal fluid (CSF) to exit into the subarachnoid space.

Median atlantoaxial joint

The median atlantoaxial joint is one of the two types of joints between the atlas (C1) and axis (C2), specifically responsible for rotational movements of the head.

Median cricothyroid ligament

The median cricothyroid ligament is a key structure in the larynx, forming the midline portion of the cricothyroid membrane. It is clinically important because it can be punctured in emergency airway access (cricothyrotomy).

Median eminence of tuber cinereum

The median eminence of the tuber cinereum is a small but crucial part of the hypothalamus that serves as a neuroendocrine interface between the brain and the pituitary gland.

Median glossoepiglottic fold

The median glossoepiglottic fold is a mucosal fold in the oropharynx that connects the tongue to the epiglottis. It is an important structure in the anatomy of the valleculae, which are clinically significant during swallowing and intubation.

Median nuclei

The term “median nuclei” generally refers to several clusters of neurons located along the midline of the brainstem or thalamus, depending on the context. These nuclei are involved in autonomic, sensory, and integrative functions.

Median raphe between mylohyoid muscles

The median raphe between the mylohyoid muscles is a fibrous midline structure in the floor of the mouth that serves as an attachment for the mylohyoid muscles and helps support oral structures.

Medulla oblongata of foramen magnum

The medulla oblongata is the lowest part of the brainstem, connecting the pons above to the spinal cord below. It contains vital autonomic centers and cranial nerve nuclei, making it essential for life-sustaining functions.

Meningeal arteries

Meningeal arteries are the arteries that supply the meninges, primarily the dura mater, and contribute to the blood supply of the cranial bones. They are clinically important because they are common sources of epidural hematomas.

Meningeal branch

A meningeal branch is a branch of an artery that specifically supplies the meninges, mainly the dura mater. These branches can arise from various arteries of the head, both from the external and internal carotid systems.

Meningeal branch of mandibular nerve

The meningeal branch of the mandibular nerve is a small sensory branch of the mandibular division (V3) of the trigeminal nerve that re-enters the cranial cavity to supply the dura mater.

Meningeal branch of maxillary nerve

The meningeal branch of the maxillary nerve is a small sensory branch of the maxillary division (V2) of the trigeminal nerve that enters the cranial cavity to supply the dura mater, particularly in the middle cranial fossa.

Meningeal branch of vagus nerve

The meningeal branch of the vagus nerve (also called the auricular branch or Arnold’s nerve when referring to part of its course) is a small branch of cranial nerve X that contributes to sensory innervation of the dura mater.

Meningeal branches of ascending pharyngeal artery

The meningeal branches of the ascending pharyngeal artery are small arteries that supply the dura mater, particularly in the posterior cranial fossa. They are clinically significant as they contribute to the dural blood supply alongside other meningeal arteries.

Meningeal branches of meningohypophyseal trunk

The meningeal branches of the meningohypophyseal trunk are small arteries arising from the internal carotid artery that supply dural structures of the posterior cranial fossa and cavernous sinus region.

Meningeal branches of vertebral arteries of foramen magnum

The meningeal branches of the vertebral arteries at the foramen magnum are small arteries that supply the dura mater and posterior cranial fossa near the craniovertebral junction.

Meninges

Meninges are the three protective membranes that surround the brain and spinal cord, providing mechanical protection, support for blood vessels, and a pathway for cerebrospinal fluid (CSF).

Meninges of foramen magnum

The meninges of the foramen magnum are the continuations of the cranial meninges (dura, arachnoid, pia) as they pass from the cranial cavity into the spinal canal, surrounding the medulla oblongata and upper cervical spinal cord.

Mental branch of inferior alveolar artery

The mental branch of the inferior alveolar artery is a small terminal branch of the inferior alveolar artery that exits the mandible to supply the chin and lower lip.

Mental foramen

The mental foramen is an important anatomical opening on the anterior surface of the mandible that allows passage of neurovascular structures to the chin and lower lip.

Mental nerve (V3)

The mental nerve is a sensory branch of the inferior alveolar nerve (V3, mandibular division of the trigeminal nerve) that exits the mental foramen to supply the chin, lower lip, and anterior mandibular gingiva.

Mental protuberance

The mental protuberance is the bony prominence at the front of the mandible that forms the point of the chin.

Mental spines (genial tubercles)

The mental spines, also called genial tubercles, are small bony projections located on the posterior (inner) surface of the mandible near the midline. They serve as important attachment points for muscles of the tongue and floor of the mouth.

Mental tubercle of mandible

The mental tubercle of the mandible is a small bony prominence located on the anterior surface of the mandible, forming part of the chin region. It is closely related to the mental protuberance.

Mental vein

The mental vein is a small vein that drains blood from the chin and lower lip. It travels through the mental foramen of the mandible alongside the mental nerve and mental artery. After passing through the foramen, it drains posteriorly into the inferior alveolar vein, which eventually connects to the facial vein or pterygoid venous plexus.

Mentalis muscle

The mentalis is a small facial muscle located in the chin area.

Meridional fibers of ciliary muscle

The meridional fibers of the ciliary muscle are one of the three fiber orientations of the ciliary muscle in the eye, which is responsible for accommodation (changing the lens shape for near vision) and aqueous humor outflow.

Mesencephalic nucleus of trigeminal nerve

The mesencephalic nucleus is a unique sensory nucleus of the trigeminal nerve (cranial nerve V) located in the midbrain (mesencephalon). It is unusual because it contains primary sensory neuron cell bodies inside the central nervous system rather than in a peripheral ganglion.

Midbrain

The midbrain, also called the mesencephalon, is a part of the brainstem that lies between the forebrain (diencephalon) and the hindbrain (pons and cerebellum). It acts as a relay center for motor and sensory pathways and plays a key role in vision, hearing, movement, and reflexes.

Middle and posterior scalene muscles

The middle and posterior scalene muscles are two of the three scalene muscles in the lateral neck (the third being the anterior scalene). They play roles in neck movement and respiration.

Middle cerebellar peduncles

The middle cerebellar peduncles are large bundles of white matter that connect the pons to the cerebellum, serving as a major pathway for communication between the cerebrum and cerebellum.

Middle cerebral artery

The middle cerebral artery (MCA) is one of the major arteries supplying the brain, and it is the largest branch of the internal carotid artery. It primarily supplies lateral aspects of the cerebral hemisphere.

Middle cerebral branches

The middle cerebral artery (MCA) gives off two main types of branches: cortical (superficial) branches and deep (lenticulostriate) branches. These supply both the lateral cerebral cortex and deep structures of the brain.

Middle cervical sympathetic cardiac nerve

The middle cervical sympathetic cardiac nerve is part of the sympathetic innervation to the heart, arising from the middle cervical ganglion of the sympathetic trunk.

Middle cervical sympathetic ganglion

The middle cervical sympathetic ganglion is one of the cervical ganglia of the sympathetic trunk, located in the neck. It gives rise to cardiac nerves and cervical branches that contribute to autonomic control of the head, neck, and heart.

Middle cranial fossa

The middle cranial fossa is a depression in the floor of the cranial cavity that houses important brain structures and neurovascular foramina. It lies between the anterior and posterior cranial fossae.

Middle ear

The middle ear is an air-filled cavity in the temporal bone that transmits sound vibrations from the tympanic membrane (eardrum) to the inner ear. It plays a crucial role in hearing by amplifying and conveying sound.

Middle ethmoidal cells

The middle ethmoidal cells (or middle ethmoidal air cells) are part of the ethmoid sinus system in the ethmoid bone, located between the nose and the orbit. They are one of three groups of ethmoidal cells: anterior, middle, and posterior.

Middle frontal sulcus

The middle frontal sulcus is a prominent groove or fissure on the lateral surface of the frontal lobe of the brain.

Middle meningeal artery

The middle meningeal artery (MMA) is a major artery that supplies the meninges (the protective coverings of the brain) and the calvaria (skull bones).

Middle meningeal plexus

The middle meningeal plexus refers to the venous network that accompanies the middle meningeal artery within the cranial cavity. It’s part of the venous drainage system of the dura mater.

Middle meningeal vein

The middle meningeal vein (MMV) is the venous counterpart of the middle meningeal artery and is part of the venous drainage of the dura mater and skull.

Middle meningeal vein of foramen spinosum

The middle meningeal vein of the foramen spinosum is essentially the portion of the middle meningeal vein that passes through the foramen spinosum alongside the middle meningeal artery.

Middle meningeal vessels of foramen spinosum

The middle meningeal vessels of the foramen spinosum refer to both the middle meningeal artery (MMA) and the middle meningeal vein (MMV) as they pass through the foramen spinosum in the skull.

Middle nasal concha of ethmoid bone

The middle nasal concha (also called the middle turbinate) is a thin, bony structure in the lateral wall of the nasal cavity, part of the ethmoid bone. It plays an important role in airflow regulation and sinus drainage.

Middle nasal meatus

The middle nasal meatus is a key passageway in the lateral wall of the nasal cavity, located beneath the middle nasal concha. It plays a critical role in sinus drainage and airflow.

Middle pharyngeal constrictor muscle

The middle pharyngeal constrictor muscle is one of the three pharyngeal constrictor muscles that form the circular layer of the pharynx.

Middle scalene muscle

The middle scalene muscle is one of the three scalene muscles in the lateral neck. It plays an important role in neck movement and respiration.

Middle superior alveolar arteries

The middle superior alveolar arteries (MSA arteries) are small branches of the maxillary artery that supply the maxillary teeth and adjacent structures.

Middle superior alveolar nerve

The middle superior alveolar nerve (MSA nerve) is a branch of the maxillary nerve (V2) that provides sensory innervation to part of the maxillary teeth and associated structures.

Middle temporal artery

The middle temporal artery (MTA) is a branch of the superficial temporal artery that primarily supplies the temporal region of the scalp and temporalis muscle.

Middle temporal vein

The middle temporal vein is a venous vessel of the temporal region that drains blood from the temporalis muscle and communicates with both superficial and deep venous systems of the head.

Middle temporal branches

The term “middle temporal branches” usually refers to the branches of the middle temporal artery that supply the temporalis muscle and overlying temporal fascia/scalp.

Middle temporal gyrus

The middle temporal gyrus (MTG) is a prominent convolution on the lateral surface of the temporal lobe of the brain. It plays important roles in language, semantic memory, and auditory processing.

Middle thyroid vein

The middle thyroid vein is a blood vessel that drains the middle part of the thyroid gland and carries the blood into the internal jugular vein.

Midline groove (median sulcus)

The midline groove, also called the median sulcus, is a longitudinal groove along the midline of a structure, often referring to muscles or organs. It essentially marks the center line dividing a structure into right and left halves.

Midsagittal

In anatomy, the term midsagittal (also called the median plane) refers to a vertical plane that divides the body into equal right and left halves.

Minor alar cartilage

The minor alar cartilages are small cartilaginous structures in the nose that help shape and support the nostrils and nasal tip.

Minor arterial circle of iris

The minor arterial circle of the iris (also called the minor circle of the iris) is a ring of blood vessels located near the pupillary margin of the iris in the eye.

Mitral cell

A mitral cell is a type of neuronal cell in the olfactory system that plays a central role in processing smell information.

Mixed fiber

In anatomy and neuroanatomy, a mixed fiber refers to a nerve fiber (axon) that carries both sensory (afferent) and motor (efferent) signals.

Modiolus of cochleus

The modiolus is the central, conical bony core of the cochlea in the inner ear. It serves as the axis around which the cochlear spiral winds and houses important neural structures.

Molar minor salivary glands

The molar minor salivary glands are small salivary glands located in the region of the upper and lower molars.

Molar tooth

A molar tooth is one of the large, flat teeth located at the back of the mouth, designed primarily for grinding and chewing food.

Motor nucleus of facial nerve

The motor nucleus of the facial nerve is a collection of neuronal cell bodies in the brainstem that gives rise to the motor fibers of the facial nerve (cranial nerve VII). It is responsible for controlling muscles of facial expression and a few other muscles.

Motor nucleus of trigeminal nerve

The motor nucleus of the trigeminal nerve is a collection of neuronal cell bodies in the brainstem that gives rise to the motor fibers of the trigeminal nerve (cranial nerve V). These fibers control muscles of mastication and a few other muscles in the head.

Motor root

In anatomy, a motor root is a bundle of nerve fibers that carries motor (efferent) signals from the central nervous system to muscles or glands. It is one component of a mixed nerve, especially in spinal and cranial nerves.

Motor root of facial nerve

The motor root of the facial nerve is the bundle of fibers that carries motor signals from the facial nerve nucleus in the pons to the muscles of the face and a few other muscles. It is the main efferent component of cranial nerve VII (facial nerve).

Motor root of trigeminal nerve

The motor root of the trigeminal nerve is the bundle of fibers that carries motor signals from the trigeminal motor nucleus in the pons to muscles of mastication and a few other muscles in the head. It is the efferent component of the mandibular division (V3) of cranial nerve V.

Mucous

In anatomy and physiology, mucous refers to a thick, slippery secretion produced by mucous membranes and glands. It plays important protective and lubricating roles in the body.

Mucous glands

Mucous glands are specialized glands that produce and secrete mucus, a thick, slippery secretion that lubricates and protects various surfaces in the body.

Mucous membrane of maxillary sinus

The mucous membrane of the maxillary sinus is the lining of the maxillary sinus, which is one of the paranasal sinuses in the skull. It plays important roles in protection, secretion, and airflow regulation.

Muscles of face

The muscles of the face are primarily responsible for facial expression, but some also assist in mastication, speech, and eye movement. Most of these muscles are innervated by the facial nerve (cranial nerve VII), except for the muscles of mastication, which are innervated by the mandibular branch of the trigeminal nerve (cranial nerve V3).

Muscles of facial expression

The muscles of facial expression are a group of muscles that move the skin of the face to produce expressions such as smiling, frowning, blinking, or pouting. Most of these muscles are innervated by the facial nerve (cranial nerve VII) and are generally attached to the skin rather than bone, allowing them to move facial features.

Muscles of neck

The muscles of the neck can be grouped based on location and function. They are involved in movement of the head, neck, shoulders, and in swallowing and respiration.

Muscles of soft palate

The muscles of the soft palate are a group of skeletal muscles that control the movement of the soft palate (the posterior, muscular part of the roof of the mouth). They are important for swallowing, speech, and closing off the nasopharynx during swallowing.

Muscular artery and vein

Muscular arteries and veins are types of blood vessels that primarily supply and drain blood from the muscles and other tissues. They have distinct structural features adapted to their function.

Muscular branch

In anatomy, a muscular branch refers to a branch of a blood vessel (artery) or a nerve that specifically supplies a muscle. These branches are targeted to provide blood flow or innervation to individual muscles or small groups of muscles.

Muscular process

In anatomy, a muscular process is a bony projection or prominence on a bone that serves as an attachment site for muscles. These processes allow muscles to anchor to the skeleton so they can generate movement or maintain posture.

Muscular process of arytenoid cartilage

The muscular process of the arytenoid cartilage is a prominent bony/cartilaginous projection on the arytenoid cartilage of the larynx that serves as an attachment site for laryngeal muscles. It is crucial for voice production and movement of the vocal cords.

Mylohyloid

The mylohyoid is a flat, triangular muscle in the floor of the oral cavity that plays an important role in swallowing, speaking, and elevating the floor of the mouth.

Mylohyoid artery

The mylohyoid artery is a small branch of the inferior alveolar artery that supplies the mylohyoid muscle and sometimes nearby structures. It runs alongside the mylohyoid nerve.

Mylohyoid branch of inferior alveolar artery

The mylohyoid branch of the inferior alveolar artery is a small arterial branch that supplies the mylohyoid muscle and nearby structures.

Mylohyoid groove

The mylohyoid groove is a bony groove on the medial surface of the mandible that provides a pathway for the mylohyoid nerve and artery. It is an important anatomical landmark in dental and maxillofacial anatomy.

Mylohyoid line

The mylohyoid line is a ridge on the inner (medial) surface of the mandible that serves as the attachment site for the mylohyoid muscle and other structures in the floor of the mouth.

Mylohyoid muscle

The mylohyoid muscle is a flat, triangular muscle that forms the floor of the oral cavity. It plays a key role in swallowing, speaking, and supporting the tongue and floor of the mouth.

Mylohyoid nerve

The mylohyoid nerve is a branch of the inferior alveolar nerve, itself a branch of the mandibular division (V3) of the trigeminal nerve (cranial nerve V). It is a motor nerve that supplies certain muscles of the floor of the mouth.

Narrowing of intervertebral foramen

Narrowing of the intervertebral foramen is a condition in which the openings between adjacent vertebrae, through which spinal nerves exit, become constricted. This can compress the spinal nerves or blood vessels passing through the foramen, leading to pain, numbness, or weakness.

Nasal bones

The nasal bones are a pair of small, oblong bones that form the bridge of the nose. They are important for the structure and shape of the nose and serve as attachment points for cartilage and facial muscles.

Nasal branch

In anatomy, the term “nasal branch” usually refers to a branch of a nerve or artery that supplies the nose or nasal cavity. There are several nerves and arteries with nasal branches, depending on the context.

Nasal branch of anterior superior alveolar nerve (V2)

The nasal branch of the anterior superior alveolar nerve is a branch of the anterior superior alveolar nerve, which itself arises from the maxillary nerve (V2) of the trigeminal nerve (cranial nerve V). It provides sensory innervation to parts of the nasal cavity.

Nasal branches of maxillary nerve

The nasal branches of the maxillary nerve (V2) are sensory branches that supply the nasal cavity. They arise from the maxillary division of the trigeminal nerve (cranial nerve V) and are responsible for innervating the mucosa of the lateral wall and septum of the nose.

Nasal cavities

The nasal cavities are two large, air-filled spaces within the nose and skull that are separated by the nasal septum. They are the main passages for airflow into the respiratory system and play key roles in breathing, filtration, humidification, olfaction, and resonance.

Nasal concha

The nasal conchae (also called turbinates) are curved bony structures on the lateral walls of the nasal cavity that increase the surface area of the nasal passages. They play an important role in filtering, warming, and humidifying inhaled air.

Nasal crest of maxilla

The nasal crest of the maxilla is a bony ridge located along the midline of the nasal cavity at the inferior part of the maxilla. It is formed where the two maxillae meet in the midline and serves as the anterior support for the vomer bone, which helps form the nasal septum.

Nasal crest of palatine bone

The nasal crest of the palatine bone is a bony ridge on the horizontal plate of the palatine bone that runs along the midline at the back of the nasal cavity.

Nasal meatus

The nasal meatus refers to one of the passageways (air channels) within the nasal cavity, located beneath each of the nasal conchae (turbinates). They are important for airflow, drainage, and sinus openings.

Nasal septal branch of superior labial branch (of facial artery)

The nasal septal branch of the superior labial artery is a small artery that supplies the front part of the nasal septum.

Nasal septal cartilage

The nasal septal cartilage is a key structure in the nose that forms the anterior part of the nasal septum, separating the two nasal cavities.

Nasal septum

The nasal septum is the wall that divides the nasal cavity into two nostrils (right and left nasal passages). It is made up of both bone and cartilage.

Nasal slit

The nasal slit generally refers to a narrow opening or fissure in the nasal region, though the exact meaning can depend on context. In anatomical terms, it usually describes small clefts or openings in the nasal cavity or associated bones.

Nasal spine of frontal bone

The nasal spine of the frontal bone is a bony projection on the lower part of the frontal bone that contributes to the bony framework of the nose.

Nasal surface of Maxilla

The nasal surface of the maxilla is the part of the maxilla bone that contributes to the lateral wall of the nasal cavity.

Nasal vestibule

The nasal vestibule is the most anterior part of the nasal cavity, just inside the nostrils. It is essentially the entrance to the nasal passages.

Nasalis muscle

The nasalis is a muscle of the nose that controls the movement of the nostrils and contributes to facial expressions.

Nasalis muscle (alar part)

The alar part of the nasalis muscle is one of the two parts of the nasalis muscle that specifically controls the nostrils.

Nasalis muscle (transverse part)

The transverse part of the nasalis muscle (also called the compressor naris) is one of the two parts of the nasalis muscle, located over the nose.

Nasociliary (sensory) root of ciliary ganglion

The nasociliary (sensory) root of the ciliary ganglion is the sensory branch that connects the nasociliary nerve (a branch of the ophthalmic division of the trigeminal nerve, V1) to the ciliary ganglion.

Nasociliary nerve (V1)

The nasociliary nerve is a major sensory branch of the ophthalmic division (V1) of the trigeminal nerve (CN V). It supplies sensation to parts of the eye, nasal cavity, and anterior cranial cavity.

It is the most medial and deepest branch of V1.

Nasociliary nerve of ophthalmic nerve (V1)

The nasociliary nerve is one of the three major branches of the ophthalmic division (V1) of the trigeminal nerve. It is a sensory nerve that supplies structures in the orbit, nasal cavity, and parts of the face.

Nasofrontal vein

The nasofrontal vein is a small superficial vein located near the root of the nose, where the nasal region meets the lower forehead. It is part of the facial venous drainage network and helps route blood from the nose toward the cavernous sinus through the ophthalmic veins.

Nasolabial facial nodes

The nasolabial lymph nodes are small, superficial lymph nodes located along the nasolabial fold—the crease running from the side of the nose to the corner of the mouth. They are part of the facial lymph node group, which helps drain lymph from the face.

Nasolabial sulcus

The nasolabial sulcus (often called the nasolabial fold) is the natural skin crease that runs from the side of the nose down to the corner of the mouth. It is one of the most visible facial surface landmarks.

Nasolacrimal duct

The nasolacrimal duct is the tube that drains tears from the eye into the nasal cavity. It is the final part of the lacrimal drainage system, which moves tears from the eye surface into the nose.

Nasolacrimal foramen

The nasolacrimal foramen is the opening of the bony nasolacrimal canal, which transmits the nasolacrimal duct from the orbit into the nasal cavity.

It is essentially the superior entrance to the nasolacrimal canal.

Nasooptic furrow

The nasooptic furrow is an embryological structure that appears during early facial development. It represents the groove between the developing nasal region and the early optic (eye) region of the embryo.

Nasopalatine nerve (V2)

The nasopalatine nerve is a sensory branch of the maxillary division (V2) of the trigeminal nerve. It supplies the nasal septum and the anterior hard palate.

Nasopalatine nerve (V2) passing to septum

The nasopalatine nerve is a sensory branch of the maxillary nerve (V2) that passes to the nasal septum and then to the anterior hard palate.

Nasopalatine nerve of incisive fossa

The nasopalatine nerve of the incisive fossa refers to the terminal portion of the nasopalatine nerve as it passes through the incisive (nasopalatine) canal/fossa to reach the anterior hard palate.

Nasopharynx

The nasopharynx is the upper part of the pharynx (throat), located behind the nasal cavity and above the soft palate. It is part of the respiratory pathway and connects the nasal cavity to the oropharynx.

Neck of mandible

The neck of the mandible is a constricted region of the mandible located just below the mandibular condyle. It connects the condylar process (head) of the mandible to the ramus, allowing articulation with the temporomandibular joint (TMJ).

Neck of tooth

The neck of a tooth (also called the cervical region) is the constricted portion of the tooth between the crown and the root. It is where the enamel of the crown meets the cementum of the root.

Nerve (Vidian) of pterygoid canal of maxillary nerve

The nerve of the pterygoid canal, also called the Vidian nerve, is a mixed autonomic nerve that carries parasympathetic and sympathetic fibers to the nasal cavity, palate, and pharynx.

Nerve fibers

A nerve fiber is a long, slender projection of a nerve cell (neuron) that transmits electrical signals (nerve impulses) between the cell body and other neurons, muscles, or glands. In simple terms, nerve fibers are the “wires” of the nervous system.

Nerve of pterygoid canal

The nerve of the pterygoid canal, also called the Vidian nerve, is a mixed autonomic nerve that carries parasympathetic and sympathetic fibers to the nasal cavity, palate, and pharynx.

Nerve to lateral pterygoid muscle (V3)

The nerve to the lateral pterygoid muscle is a motor branch of the mandibular division (V3) of the trigeminal nerve that innervates the lateral pterygoid muscle, one of the key muscles of mastication.

Nerve to medial pterygoid and tensor veli palatini muscles (V3)

The nerve to the medial pterygoid and tensor veli palatini muscles is a motor branch of the mandibular division (V3) of the trigeminal nerve. It supplies medial pterygoid, tensor veli palatini, and tensor tympani muscles.

Nerve to mylohyoid (V3)

The nerve to mylohyoid is a branch of the inferior alveolar nerve, which itself is a branch of the mandibular division (V3) of the trigeminal nerve. It provides motor innervation to the mylohyoid muscle and the anterior belly of the digastric muscle.

Nerve to posterior belly of digastric muscle and to stylohyoid muscle

The nerve to the posterior belly of the digastric muscle and to the stylohyoid muscle is a branch of the facial nerve (cranial nerve VII) that provides motor innervation to these muscles.

Nerve to stapedius muscle

The nerve to the stapedius muscle is a small motor branch of the facial nerve (cranial nerve VII) that innervates the stapedius muscle in the middle ear.

Nerve to thyrohyoid muscle (C1, C2, via XII)

The nerve to the thyrohyoid muscle is a motor nerve that primarily carries fibers from C1 (and sometimes C2), but it travels along the hypoglossal nerve (cranial nerve XII) to reach its target.

Nerves IX, X, and XI in carotid sheath

The glossopharyngeal (IX), vagus (X), and accessory (XI) nerves pass through or are closely related to the carotid sheath in the neck.

Nerves of larynx

The nerves of the larynx are branches of the vagus nerve (cranial nerve X). They provide motor, sensory, and autonomic innervation to the larynx, which is essential for voice, swallowing, and airway protection.

Nerves of nasal cavity

The nerves of the nasal cavity provide sensory (olfactory and general), autonomic (secretomotor and vasomotor), and some reflex fibers. Most of them are branches of the olfactory nerve (CN I), the trigeminal nerve (CN V), and the facial nerve (CN VII, via autonomic fibers).

Nerves of orbit

The nerves of the orbit are primarily branches of the ophthalmic division of the trigeminal nerve (V1), along with contributions from cranial nerves III (oculomotor), IV (trochlear), VI (abducens), and the sympathetic fibers. They provide sensory, motor, and autonomic innervation to the eye, extraocular muscles, eyelids, lacrimal gland, and orbital structures.

Nerves to anterior longus capitis muscle

The anterior scalene and longus capitis muscles are prevertebral muscles of the neck, and the nerve supply to the anterior longus capitis comes primarily from the cervical spinal nerves.

Nerves to anterior rectus capitis muscle

The anterior rectus capitis muscle (also called rectus capitis anterior) is a small prevertebral muscle that helps flex the head at the atlanto-occipital joint. Its nerve supply comes from the cervical spinal nerves.

Nerves to anterior colli muscles

The anterior colli muscles (also called prevertebral cervical muscles or longus colli muscles) are a group of deep neck flexors that run along the anterior aspect of the cervical vertebrae. Their innervation comes from cervical spinal nerves.

Nerves to colli muscle

The colli muscles generally refer to the longus colli muscles (also called the anterior cervical or prevertebral muscles) in the neck, which flex and stabilize the cervical spine. Their nerve supply comes from the cervical spinal nerves.

Nerves to lateral colli muscles

The lateral colli muscles are part of the prevertebral muscles of the neck, mainly referring to the scalenus (scalene) muscles: anterior, middle, and posterior scalene. These are lateral cervical muscles that flex and stabilize the neck and elevate the first two ribs during respiration. Their nerve supply comes from the cervical spinal nerves.

Nerves to lateral longus capitis muscle

The lateral longus capitis muscle (often just called longus capitis) is a prevertebral lateral cervical muscle that flexes the head at the atlanto-occipital joint. Its innervation comes from cervical spinal nerves.

Nerves to lateral rectus capitis muscle

The lateral rectus capitis muscle (also called rectus capitis lateralis) is innervated by the ventral rami of cervical spinal nerves C1 and C2.

Nerves to levator scapulae muscle

The levator scapulae muscle is supplied by the dorsal scapular nerve (C5) as well as the cervical spinal nerves (C3 and C4).

Nerves to longus capitis muscle

The longus capitis muscle is supplied by the cervical spinal nerves C1 to C3 and also, sometimes, C4.

Nerves to middle scalene muscle

The middle scalene muscle is innervated by the ventral rami of cervical spinal nerves C3–C8.

Nerves to superior and inferior bellies of omohyoid, sternohyoid, and sternothyroid muscles (ansa cervicalis)

The infrahyoid (“strap”) muscles—omohyoid, sternohyoid, and sternothyroid—are mainly innervated by the ansa cervicalis, which is a loop of nerves formed by cervical spinal nerves.

Neurohypophysis (posterior lobe of pituitary gland)

The neurohypophysis is the posterior lobe of the pituitary gland, also called the posterior pituitary. It differs from the anterior pituitary (adenohypophysis) in structure and function.

Nodule of inferior vermis

The nodule of the inferior vermis is a specific part of the cerebellar vermis, located in the posterior/inferior portion of the cerebellum.

Nodulus of vermis of cerebellum

The nodulus (or nodule) is a specific part of the vermis of the cerebellum, located in its inferior (posterior) portion.

Nonpigmented and pigmented regions of retina

The retina is the light-sensitive layer at the back of the eye, and it has two main regions: the pigmented layer and the nonpigmented (neural) layer.

Nose

The nose is the prominent external structure on the face and the entrance to the respiratory system. It serves both respiratory and olfactory functions.

Nuclear layer of medulla oblongata

The medulla oblongata is the caudal part of the brainstem, connecting the spinal cord to the pons. Its nuclear layers consist of groups of gray matter nuclei embedded within the white matter, responsible for motor, sensory, and autonomic functions.

Nuclei

Nuclei in neuroanatomy are clusters of neuron cell bodies located within the central nervous system (brain or spinal cord). They are regions of gray matter that serve as centers for processing specific types of information or controlling particular functions.

Nucleus ambiguus

The nucleus ambiguus is a motor nucleus in the medulla oblongata that controls muscles of the pharynx, larynx, and upper esophagus. It is important for swallowing, speech, and parasympathetic functions.

Nucleus ambiguus (motor to pharyngeal and laryngeal muscles)

The nucleus ambiguus is a motor nucleus in the medulla oblongata that provides motor innervation to muscles of the pharynx and larynx, as well as the soft palate.

Nucleus of lens

The lens of the eye itself does not contain a nucleus in the neural sense, but it does have a structure called the lens nucleus, which is part of its anatomy.

Nucleus of solitary tract

The nucleus of the solitary tract (also called the solitary nucleus) is a major sensory nucleus in the medulla oblongata that processes visceral and taste information.

Nucleus of trigeminal nerve

The trigeminal nerve (CN V) has several nuclei in the brainstem that handle sensory and motor functions. Collectively, these are referred to as the trigeminal nuclear complex.

Nucleus pulposus

The nucleus pulposus is the central core of an intervertebral disc, which acts as a shock absorber between the vertebrae.

Obex

The obex is an anatomical landmark in the medulla oblongata of the brainstem.

Oblique and transverse arytenoid muscles

The oblique and transverse arytenoid muscles are intrinsic muscles of the larynx that play key roles in voice production and airway protection.

Oblique line of mandible

The oblique line is a ridge on the external surface of the mandible (lower jawbone) that serves as an attachment site for muscles.

Oblique line of thyroid cartilage

The oblique line of the thyroid cartilage is a ridge on the lateral surface of the thyroid cartilage that serves as an attachment site for muscles of the larynx and pharynx.

Oblique part of cricothyroid muscle

The oblique part of the cricothyroid muscle is one of the two parts of the cricothyroid muscle, an intrinsic laryngeal muscle that plays a key role in tensioning the vocal cords for phonation.

Occipital (posterior) horn of lateral ventricle

The occipital (posterior) horn of the lateral ventricle is a part of the lateral ventricle in the brain that extends into the occipital lobe.

Occipital (posterior) horn of left lateral ventricle

The occipital (posterior) horn of the left lateral ventricle is the posterior extension of the left lateral ventricle into the occipital lobe of the brain. Its anatomy and function are essentially the same as the general occipital horn, but specifying the left side is important for imaging, neurosurgery, or lateralized pathology.

Occipital (posterior) horn of right lateral ventricle

The occipital (posterior) horn of the right lateral ventricle is the posterior extension of the right lateral ventricle into the occipital lobe. Like the left, it serves as a CSF reservoir and is a key landmark in neuroanatomy and imaging.

Occipital artery

The occipital artery is a branch of the external carotid artery that supplies the posterior scalp, muscles of the neck, and meninges.

Occipital belly (occipitalis) of epicranius muscle

The occipital belly (occipitalis) of the epicranius muscle is the posterior portion of the epicranius (or occipitofrontalis) muscle, which is responsible for moving the scalp.

Occipital belly of occipitofrontalis muscle

The occipital belly of the occipitofrontalis muscle (also called the occipitalis) is the posterior portion of the epicranius muscle, which moves the scalp and works with the frontal belly for facial expression.

Occipital bone

The occipital bone is a cranial bone that forms the posterior and inferior part of the skull. It plays a crucial role in protecting the brain and providing attachment points for muscles and ligaments.

Occipital branch of posterior auricular nerve

The occipital branch of the posterior auricular nerve is a branch of the facial nerve (cranial nerve VII) that supplies part of the occipital (posterior scalp) region.

Occipital condyle of occipital bone

The occipital condyles are paired, rounded projections on the inferior surface of the occipital bone that articulate with the first cervical vertebra (atlas, C1), forming the atlanto-occipital joint.

Occipital diploic vein

The occipital diploic vein is one of the diploic veins, which are veins within the diploë (spongy bone) of the cranial bones. These veins help drain the cranial bones and communicate with both intracranial and extracranial venous systems.

Occipital emissary vein

The occipital emissary vein is a venous channel that connects the extracranial venous system (scalp) with the intracranial dural venous sinuses, specifically in the occipital region of the skull.

Occipital groove (for occipital artery) of temporal bone

The occipital groove of the temporal bone is a bony groove on the squamous part of the temporal bone that provides a pathway for the occipital artery.

Occipital horn of lateral ventricle

The occipital horn of the lateral ventricle (also called the posterior horn) is a part of the lateral ventricle of the brain that extends into the occipital lobe.

Occipital lobe

The occipital lobe is the posterior lobe of the cerebral hemisphere primarily responsible for visual processing.

Occipital nerve

The term “occipital nerve” usually refers to the greater occipital nerve and lesser occipital nerve, which are sensory nerves supplying the posterior scalp.

Occipital nodes

The occipital lymph nodes are a group of superficial lymph nodes located at the back of the head that drain lymph from the posterior scalp.

Occipital pole

The occipital pole is an anatomical term referring to the most posterior (rear) tip of the occipital lobe of the brain. It is part of the cerebral cortex located in the posterior cranial fossa.

Occipital pole of cerebrum

The occipital pole of the cerebrum refers specifically to the most posterior tip of the occipital lobe in the cerebral hemisphere. It’s a key landmark in neuroanatomy because it’s closely tied to visual processing.

Occipital sinus

The occipital sinus is a small, midline venous channel located within the falx cerebelli, a fold of dura mater between the two cerebellar hemispheres.

Occipital vein

The occipital vein is a superficial vein of the posterior scalp and neck region.

Occipitoemporal sulcus

The occipitotemporal sulcus, also known as the fusiform sulcus, is an important anatomical landmark on the inferior (ventral) surface of the brain.

Occipitomastoid suture

The occipitomastoid suture is a cranial suture that connects the occipital bone with the mastoid portion of the temporal bone.

Occipitotemporal branches

The term “occipitotemporal branches” generally refers to branches of arteries or nerves that supply the occipitotemporal region of the skull and scalp.

Occipitotemporal sulcus

The occipitotemporal sulcus, also known as the fusiform sulcus, is a brain sulcus on the inferior (ventral) surface of the cerebral hemisphere.

Occipital pole of cerebrum

The occipital pole of the cerebrum is the most posterior tip of the occipital lobe of the brain. It is an important anatomical landmark because it is closely associated with the primary visual cortex.

Oculomotor nerve (III)

The oculomotor nerve is the third cranial nerve (CN III) and is primarily a motor nerve that controls most of the eye movements.

Oculomotor nerve (III) of superior orbital fissure

The oculomotor nerve (cranial nerve III) at the superior orbital fissure refers to the segment of the nerve as it enters the orbit from the cranial cavity.

Oculomotor nucleus

The oculomotor nucleus is the motor nucleus of the oculomotor nerve (cranial nerve III), located in the midbrain. It’s responsible for controlling most of the extraocular muscles and the levator palpebrae superioris.

Oculomotor root of ciliary ganglion

The oculomotor root of the ciliary ganglion refers to the preganglionic parasympathetic fibers of the oculomotor nerve (CN III) that synapse in the ciliary ganglion. These fibers are responsible for pupil constriction and lens accommodation.

Odontoblast layer

The odontoblast layer is a key histological structure in tooth anatomy. It is responsible for the formation of dentin, the hard tissue beneath the enamel and cementum.

Odontoid

The odontoid refers to the odontoid process, also known as the dens, which is a prominent bony projection of the axis (C2 vertebra). It is a crucial structure for cervical spine stability and rotation.

Olfactory bulbs

The olfactory bulbs are paired structures of the forebrain that are essential for the sense of smell (olfaction).

Olfactory cells

Olfactory cells are specialized sensory neurons responsible for detecting odors in the nasal cavity. They are the primary receptors of the olfactory system.

Olfactory mucosa

The olfactory mucosa (or olfactory epithelium) is the specialized region of the nasal mucosa responsible for detecting odors. It contains the olfactory receptor cells and associated supporting structures.

Olfactory nerve

The olfactory nerve is cranial nerve I (CN I), and it is responsible for smell (olfaction). It is unique among cranial nerves because it is a purely sensory nerve and directly connects the nasal epithelium to the brain.

Olfactory nerve bundles of foramina of cribriform plate

The olfactory nerve bundles passing through the foramina of the cribriform plate are the axons of olfactory receptor cells that carry smell information from the nasal cavity to the brain.

Olfactory nerve fibers

The olfactory nerve fibers are the axons of olfactory receptor neurons that carry smell information from the nasal epithelium to the brain.

Olfactory nerves (I)

The olfactory nerves are cranial nerve I (CN I) and are responsible for the sense of smell (olfaction). They are unique among cranial nerves because they are purely sensory and directly connect the nasal epithelium to the brain.

Olfactory sulcus

The olfactory sulcus is a groove on the inferior (orbital) surface of the frontal lobe of the brain that accommodates the olfactory bulb and tract.

Olfactory tract

The olfactory tract is the bundle of axons that carries sensory information from the olfactory bulb to the brain, playing a central role in the sense of smell.

Olfactory trigone

The olfactory trigone is a small, triangular area on the inferior surface of the frontal lobe that serves as a landmark where the olfactory tract divides.

Olfactory tubercle

The olfactory tubercle is a small structure on the ventral surface of the frontal lobe that is part of the olfactory cortex and involved in processing smell.

Olive

In anatomy, the term “olive” usually refers to a prominent oval-shaped structure on the surface of the medulla oblongata in the brainstem. It is an important landmark in neuroanatomy.

Omohyoid muscle

The omohyoid muscle is a thin, strap-like (infrahyoid) muscle of the neck that helps depress the hyoid bone and stabilize it during swallowing and speech.

Omohyoid muscle (inferior belly)

The inferior belly of the omohyoid muscle is the lower portion of the omohyoid, a thin, strap-like infrahyoid muscle in the neck. It plays a role in hyoid depression and neck fascial tension.

Opening into middle nasal meatus

The middle nasal meatus is a passage within the lateral wall of the nasal cavity, and several structures open into it.

Opening of auditory (pharyngotympanic, Eustachian) tube

The opening of the auditory tube (also called the pharyngotympanic or Eustachian tube) is the nasopharyngeal orifice that connects the middle ear cavity to the nasopharynx.

Opening of frontonasal canal

The opening of the frontonasal canal is the nasal ostium through which the frontal sinus drains into the nasal cavity, usually via the frontonasal duct (infundibulum).

Opening of frontonasal duct

The opening of the frontonasal duct is the nasal ostium through which the frontal sinus drains into the nasal cavity, usually into the middle nasal meatus via the ethmoidal infundibulum.

Opening of maxillary sinus

The opening of the maxillary sinus is the ostium through which the maxillary sinus drains into the nasal cavity, specifically into the middle nasal meatus.

Opening of middle ethmoidal cells

The middle ethmoidal cells (air cells of the ethmoid bone) drain into the middle nasal meatus. Their openings are important landmarks in sinus anatomy and endoscopic surgery.

Opening of nasolacrimal canal

The opening of the nasolacrimal canal is the nasal ostium of the nasolacrimal duct, which allows drainage of tears from the lacrimal sac into the nasal cavity.

Opening of nasolacrimal duct

The opening of the nasolacrimal duct is the nasal ostium where the nasolacrimal duct drains tears into the nasal cavity. It is essentially the terminal part of the nasolacrimal drainage system.

Opening of sphenoidal sinus

The opening of the sphenoidal sinus is the nasal ostium through which the sphenoid sinus drains into the nasal cavity.

Opening of superior cerebral vein

The superior cerebral veins are veins on the surface of the cerebral hemispheres that drain the cortex and subcortical white matter into the dural venous sinuses, primarily the superior sagittal sinus. Their “opening” refers to the points where they enter the sinus.

Openings into maxillary sinus

The maxillary sinus (largest of the paranasal sinuses) has openings that allow drainage into the nasal cavity.

Openings of middle ethmoidal cells

The middle ethmoidal cells (or middle ethmoidal air cells) are part of the ethmoid sinus system in the lateral wall of the nasal cavity. Their openings drain into the middle nasal meatus, specifically into the ethmoidal bulla, which is a rounded elevation in the lateral wall of the middle meatus.

Openings of posterior ethmoidal cells

The posterior ethmoidal cells (or posterior ethmoid air cells) are part of the ethmoid sinus system located in the posterior part of the ethmoid labyrinth. Their openings are slightly different from the anterior and middle cells.

Openings of tarsal glands

The tarsal glands (also called Meibomian glands) are specialized sebaceous glands located in the tarsal plates of the eyelids. They secrete lipid-rich meibum that helps prevent evaporation of the tear film.

Opercular part of inferior frontal gyrus

The opercular part of the inferior frontal gyrus (IFG) is one of the three anatomical subdivisions of the IFG in the frontal lobe, the others being the triangular part and orbital part.

Ophthalmic (V1) and Maxillary (V2) Nerves

The ophthalmic (V1) and maxillary (V2) nerves are the first two divisions of the trigeminal nerve (cranial nerve V), which is the main sensory nerve of the face.

Ophthalmic artery

The ophthalmic artery is the first branch of the internal carotid artery that supplies blood to the eye, orbit, and surrounding structures.

Ophthalmic artery of optic canal

The ophthalmic artery in the optic canal refers to the portion of the ophthalmic artery as it enters and travels through the optic canal alongside the optic nerve (CN II).

Ophthalmic division of trigeminal nerve

The ophthalmic division of the trigeminal nerve is the first division (V1) of the trigeminal nerve, cranial nerve V. It is a purely sensory nerve that carries sensation from the upper part of the face and orbit.

Ophthalmic nerve (V1)

The ophthalmic nerve (V1) is the first division of the trigeminal nerve (cranial nerve V) and is a purely sensory nerve. It transmits sensation from the upper part of the face and the orbit.

Optic (visual) part of retina

The optic (visual) part of the retina is the portion of the retina that is sensitive to light and capable of forming visual images. It contrasts with the non-visual (or blind) part of the retina, which lines the ciliary body and iris.

Optic canal

The optic canal is a short, bony passage in the sphenoid bone that transmits the optic nerve (CN II) and the ophthalmic artery from the cranial cavity into the orbit.

Optic canal (foramen)

The optic canal (optic foramen) is a short, cylindrical passage in the lesser wing of the sphenoid bone that connects the middle cranial fossa to the orbit. It serves as the pathway for the optic nerve (CN II) and the ophthalmic artery.

Optic canal of Sphenoid bone

The optic canal of the sphenoid bone is a bony passage in the lesser wing of the sphenoid that connects the middle cranial fossa with the orbit, allowing passage of the optic nerve (CN II) and the ophthalmic artery.

Optic chiasm

The optic chiasm is a critical structure in the visual pathway where the optic nerves (CN II) from each eye partially cross before continuing as the optic tracts to the brain.

Optic disc

The optic disc (also called the optic nerve head) is the point on the retina where the optic nerve (CN II) exits the eye. It is often referred to as the “blind spot” because it lacks photoreceptor cells, so it cannot detect light.

Optic nerve (II)

The optic nerve (cranial nerve II, CN II) is the sensory nerve responsible for vision, transmitting visual information from the retina to the brain.

Optic nerve (II) and outer sheath

The optic nerve (cranial nerve II, CN II) is the sensory nerve of vision, and it is unique among cranial nerves because it is an extension of the central nervous system (CNS) rather than a peripheral nerve. Its outer sheath reflects this CNS origin.

Optic nerve (II) of optic canal

The optic nerve (cranial nerve II, CN II) in the optic canal refers to the portion of the optic nerve as it passes from the middle cranial fossa into the orbit through the optic canal in the lesser wing of the sphenoid bone.

Optic part of retina

The optic (visual) part of the retina is the light-sensitive portion of the retina responsible for vision. It differs from the non-visual (pars ceca) retina, which lines the ciliary body and iris and is not photosensitive.

Optic radiation

The optic radiation is a bundle of axons (white matter fibers) that carry visual information from the lateral geniculate nucleus (LGN) of the thalamus to the primary visual cortex in the occipital lobe. It is a key part of the visual pathway.

Optic tract

The optic tract is a continuation of the optic nerve fibers after the optic chiasm, carrying visual information from the retina to the lateral geniculate nucleus (LGN) of the thalamus.

Ora serrata

The ora serrata is the anterior boundary between the photosensitive (optic) and non-photosensitive (ciliary) parts of the retina in the eye.

Oral cavity

The oral cavity is the entrance to the digestive system, responsible for ingestion, initial digestion, and speech. It includes the mouth proper and the vestibule and contains important structures for chewing, taste, and swallowing.

Orbicularis oculi muscle

The orbicularis oculi is a muscle of facial expression that surrounds the eyelids and is primarily responsible for closing the eye.

Orbicularis of ciliary body covered by ciliary part of retina

The “orbicularis of the ciliary body” refers to the circular (sphincteric) fibers of the ciliary muscle, which are part of the ciliary body and control lens accommodation.

The inner surface of the ciliary body, including this ciliary muscle, is covered by the ciliary part of the retina (also called pars ciliaris retinae), which is a non-photosensitive portion of the retina.

Orbicularis oris muscle

The orbicularis oris is a muscle of facial expression that encircles the mouth and is primarily responsible for controlling movements of the lips.

Orbiculus ciliaris of ciliary body

The orbiculus ciliaris (also called the circular fibers of the ciliary muscle) is a smooth muscle of the ciliary body in the eye, responsible for accommodation of the lens for near vision.

Orbit

The orbit is the bony cavity in the skull that houses the eyeball and its associated structures, including muscles, nerves, blood vessels, and fat. It serves to protect the eye, support its movements, and provide passage for neurovascular structures.

Orbital fat

Orbital fat is the adipose tissue within the orbit that surrounds and cushions the eyeball and orbital structures. It is essential for protection, support, and smooth movement of the eye.

Orbital gyri

The term “orbital gyri” refers to the folded ridges on the inferior (orbital) surface of the frontal lobe of the brain, which lie directly above the orbit. These gyri are part of the orbitofrontal cortex, involved in decision-making, emotion, and olfaction.

Orbital muscles

The orbital muscles are the muscles located in and around the orbit that control movement of the eyeball, eyelids, and assist in tear drainage. They include extraocular muscles, eyelid muscles, and the ciliary muscle of the ciliary body.

Orbital operculum

The orbital operculum is a part of the frontal lobe of the brain that covers the orbital (inferior) surface of the frontal gyri, lying over the roof of the orbit. It forms part of the frontal cortex involved in higher cognitive functions.

Orbital part of inferior frontal gyrus

The orbital part of the inferior frontal gyrus is the portion of the inferior frontal gyrus located on the orbital (inferior) surface of the frontal lobe, lying directly above the orbit. It is part of the frontal cortex and contributes to cognitive, emotional, and language functions.

Orbital part of lacrimal gland

The orbital part of the lacrimal gland is the larger, superior portion of the lacrimal gland located in the superolateral part of the orbit. It is responsible for producing the bulk of the aqueous portion of tears.

Orbital part of orbicularis oculi muscle

The orbital part of the orbicularis oculi muscle is the portion of the orbicularis oculi that surrounds the bony orbit, responsible for forceful closure of the eyelids. It is distinct from the palpebral part, which lies within the eyelids for gentle blinking.

Orbital plate of ethmoid bone

The orbital plate of the ethmoid bone is a thin bony structure that forms a major part of the medial wall of the orbit. It is also called the lamina papyracea because of its paper-thin nature.

Orbital process of palatine bone

The orbital process of the palatine bone is a small bony projection that contributes to the floor and posteromedial part of the orbit. It is part of the palatine bone, which primarily forms the posterior part of the hard palate.

Orbital septum

The orbital septum is a fibrous membrane forming the anterior boundary of the orbit, separating the eyelid from the orbital contents. It plays a crucial role in protecting the orbit from infection and trauma.

Orbital sulci

The orbital sulci are shallow grooves on the inferior (orbital) surface of the frontal lobe of the brain. They separate the orbital gyri and help define the folded pattern of the orbitofrontal cortex.

Orbital surface

The orbital surface generally refers to any bony surface that forms part of the orbit, but it is most often used in reference to the orbital surface of specific bones (e.g., frontal bone, maxilla, zygomatic bone, ethmoid bone, palatine bone, sphenoid bone). These surfaces collectively form the walls and floor of the orbit, providing support and protection for the eye and orbital contents.

Orbital surface of frontal bone

The orbital surface of the frontal bone is the part of the frontal bone that forms the roof of the orbit. It separates the orbital cavity from the anterior cranial fossa and provides protection for the eye and orbital contents.

Orbital surface of greater wing of sphenoid bone

The orbital surface of the greater wing of the sphenoid bone is the part of the sphenoid that contributes to the lateral wall of the orbit. It forms a smooth bony area that helps protect the eye and provides passage for neurovascular structures.

Orbital surface of lesser wing of sphenoid bone

The orbital surface of the lesser wing of the sphenoid bone is a small, smooth bony area that contributes to the roof of the orbit, forming part of the posterior portion of the orbital roof. It is closely related to the optic canal and the superior orbital fissure.

Orbital surface of maxilla

The orbital surface of the maxilla is the portion of the maxilla that forms the floor of the orbit. It is a key structural component that supports the eyeball and separates the orbit from the maxillary sinus below.

Orbital surface of zygomatic bone

The orbital surface of the zygomatic bone is the part of the zygomatic bone that contributes to the lateral wall and part of the floor of the orbit. It provides structural support and protection for the eye and serves as a site of articulation with surrounding bones.

Orientation of labyrinth in skull

The labyrinth of the ethmoid bone (also called the ethmoidal labyrinth) is a complex, air-filled structure forming the medial wall of the orbit and part of the nasal cavity. Its orientation in the skull is important for nasal airflow, paranasal sinus anatomy, and orbital relations.

Oropharynx

The oropharynx is the middle part of the pharynx, located posterior to the oral cavity. It serves as a passageway for both air and food and plays a role in swallowing, speech, and immune defense.

Osseous cochlea

The osseous cochlea (also called the bony cochlea) is the spiral-shaped, bony part of the inner ear that houses the cochlear duct and the organ of Corti, playing a central role in hearing.

Osseous spiral lamina

The osseous spiral lamina is a thin, bony shelf that projects from the modiolus into the cochlea, partially dividing the scala vestibuli and scala tympani of the osseous cochlea. It plays a key role in supporting the cochlear duct and organ of Corti.

Ossification

Ossification is the process by which new bone is formed in the body. It is essential for skeletal development, growth, and repair. There are two main types of ossification, each with distinct mechanisms and locations.

Otic capsule

The otic capsule is the dense bony structure that surrounds and protects the membranous labyrinth of the inner ear, including the cochlea, vestibule, and semicircular canals. It is part of the temporal bone and plays a key role in hearing and balance.

Otic ganglion

The otic ganglion is a small parasympathetic ganglion associated with the glossopharyngeal nerve (CN IX). It is located just below the foramen ovale, medial to the mandibular nerve (V3), and plays a key role in innervating the parotid gland.

Outer hair cells

Outer hair cells (OHCs) are specialized sensory cells of the cochlea in the organ of Corti that play a critical role in amplifying sound and enhancing frequency selectivity in hearing.

Outer sheath of optic nerve

The outer sheath of the optic nerve refers to the protective covering surrounding the optic nerve (cranial nerve II) as it passes from the eye to the brain. It is continuous with the meninges of the brain, providing both protection and a conduit for cerebrospinal fluid (CSF).

Outline of 4th ventricle

The fourth ventricle is a diamond-shaped cavity in the hindbrain that lies between the brainstem (pons and medulla) anteriorly and the cerebellum posteriorly. It is part of the ventricular system of the brain and is filled with cerebrospinal fluid (CSF).

Oval (vestibular) window

The oval window (also called the vestibular window) is a membrane-covered opening in the bony wall of the inner ear that transmits vibrations from the middle ear to the inner ear, playing a crucial role in hearing.

Oval (vestibular) window of temporal bone

The oval (vestibular) window of the temporal bone is the bony opening in the medial wall of the middle ear that communicates with the vestibule of the inner ear. It is essential for transmitting vibrations from the middle ear to the cochlea.

Palate

The palate is the structure forming the roof of the mouth and the floor of the nasal cavity. It separates the oral and nasal cavities, allowing simultaneous breathing and chewing.

Palatine aponeurosis (from tensor veli palatini muscle)

The palatine aponeurosis is a fibrous sheet that forms the structural framework of the soft palate. It serves as the central tendon of the tensor veli palatini muscle and provides attachment for several other palatal muscles.

Palatine bone

The palatine bone is a paired L-shaped bone located at the posterior part of the nasal cavity. Each bone contributes to the hard palate, nasal cavity, and orbit.

Palatine glands

Palatine glands are minor salivary glands located in the mucosa of the hard and soft palate. They are part of the continuous system of ~600 minor salivary glands throughout the oral cavity.

Palatine nerves (V2)

These nerves are branches of the maxillary nerve (CN V2) that supply the palate, nasal cavity, and adjacent mucosa. They descend through the pterygopalatine fossa, pass through the pterygopalatine ganglion, and reach the palate via the greater and lesser palatine canals.

Palatine process of maxilla

The palatine process of the maxilla is a horizontal bony plate that projects medially from the maxilla to form the anterior two-thirds of the hard palate and the floor of the nasal cavity.

Palatine raphe

The palatine raphe (or median palatine raphe) is a narrow, raised midline ridge running along the hard palate on its oral surface.

Palatine tonsil

The palatine tonsil is a paired mass of lymphoid tissue located in the oropharynx. It is one of the main components of the Waldeyer’s ring, the ring of lymphoid tissue guarding the entrance to the respiratory and digestive tracts.

Palatine vein

The palatine vein (more often referred to in the plural: greater and lesser palatine veins, or palatine venous plexus) is a venous drainage pathway that accompanies the greater and lesser palatine arteries and nerves through the palatine canals and drains the hard and soft palate.

Palatine nerves

The palatine nerves are branches of CN V2 (maxillary nerve) that carry sensory fibers, and also parasympathetic and sympathetic fibers to the palate and associated glands. They pass through the pterygopalatine fossa and reach the palate via the palatine canals.

Palatoglossal arch

The palatoglossal arch, also called the anterior tonsillar pillar, is a mucosal fold in the oropharynx formed by the palatoglossus muscle covered with mucosa. It plays a key role in swallowing and defines part of the tonsillar region.

Palatoglossus muscle

The palatoglossus is an extrinsic muscle of the tongue that forms the core of the palatoglossal arch (anterior tonsillar pillar). It plays a key role in swallowing and soft palate movement.

Palatopharyngeal arch

The palatopharyngeal arch, also called the posterior tonsillar pillar, is a mucosal fold in the oropharynx formed by the palatopharyngeus muscle covered with mucosa. It lies posterior to the palatine tonsil and is important in swallowing and soft palate function.

Palatopharyngeal sphincter (Passavant's ridge)

The palatopharyngeal sphincter, commonly called Passavant’s ridge, is a ridge on the posterior pharyngeal wall formed by the converging fibers of the soft palate and pharyngeal muscles. It plays a crucial role in velopharyngeal closure during swallowing and speech.

Palatopharyngeus muscle

The palatopharyngeus is a muscle of the soft palate and pharynx that forms the core of the palatopharyngeal arch (posterior tonsillar pillar). It plays a crucial role in swallowing, speech, and velopharyngeal closure.

Palpebral branch of lacrimal nerve

The palpebral branch of the lacrimal nerve is a sensory branch of the lacrimal nerve (V1, ophthalmic division of the trigeminal nerve) that supplies part of the upper eyelid.

Palpebral conjunctiva

The palpebral conjunctiva is the mucous membrane lining the inner surface of the eyelids. It is continuous with the bulbar conjunctiva, which covers the anterior surface of the eyeball.

Palpebral part of lacrimal gland

The palpebral part is one of the two main lobes of the lacrimal gland, the exocrine gland responsible for tear production. It is located in the superolateral orbit and lies against the eyelid.

Palpebral part of orbicularis oculi muscle

The palpebral part is the eyelid portion of the orbicularis oculi, a circular muscle around the orbit responsible for eyelid closure. It is distinct from the orbital part, which surrounds the orbital rim and is involved in forceful closure.

Pancreas

The pancreas is a retroperitoneal gland with both exocrine and endocrine functions, located in the upper abdomen behind the stomach. It plays a key role in digestion and glucose metabolism.

Papilla

In anatomy, a papilla refers to a small, nipple-like projection or elevation on a tissue or organ. Papillae are common in multiple systems, including skin, tongue, kidney, and glands. The exact structure and function depend on the location.

Paracentral artery

The paracentral artery is a branch of the central retinal artery, supplying the inner retina near the macula, especially the papillomacular bundle, which is critical for central vision.

Paracentral lobule

The paracentral lobule is a region on the medial surface of the cerebral hemisphere that contains parts of the primary motor and primary sensory cortices responsible for controlling and receiving sensory input from the contralateral lower limb and foot.

Paracentral sulcus

The paracentral sulcus is a shallow groove on the medial surface of the cerebral hemisphere that serves as an anatomical landmark for the paracentral lobule.

Parahippocampal gyrus

The parahippocampal gyrus is a medial temporal lobe structure involved in memory encoding and retrieval, spatial navigation, and limbic system functions.

Paranasal sinuses

The paranasal sinuses are air-filled cavities within the bones of the skull and face, lined with respiratory mucosa. They are connected to the nasal cavity and play roles in lightening the skull, humidifying air, resonance of voice, and immune defense.

Parasympathetic fibers

Parasympathetic fibers are part of the autonomic nervous system (ANS) responsible for the “rest-and-digest” functions of the body, in contrast to sympathetic fibers which mediate “fight-or-flight” responses. They are motor fibers that influence glands, smooth muscles, and cardiac muscle.

Parasympathetic postganglionic fibers

Parasympathetic postganglionic fibers are the second-order neurons of the parasympathetic nervous system. They extend from autonomic ganglia to target organs, mediating the characteristic “rest-and-digest” responses.

Parasympathetic preganglionic fibers

Parasympathetic preganglionic fibers are the first-order neurons of the parasympathetic division of the autonomic nervous system. They originate in the central nervous system (CNS) and synapse in parasympathetic ganglia near or within the target organs.

Parasympathetic root of ciliary ganglion

The parasympathetic root of the ciliary ganglion carries preganglionic parasympathetic fibers from the oculomotor nerve (CN III) to the ganglion, which then sends postganglionic fibers to the eye to control pupil constriction and lens accommodation.

Parathyroid gland

The parathyroid glands are small endocrine glands located in the neck that are critical for calcium and phosphate homeostasis via secretion of parathyroid hormone (PTH).

Paraventricular hypothalamic nucleus

The paraventricular nucleus (PVN) is a critical hypothalamic nucleus involved in neuroendocrine regulation, autonomic control, and stress responses.

Paraventricular nuclei of hypothalamus

The paraventricular nuclei (PVN) are a paired set of nuclei in the hypothalamus, located adjacent to the third ventricle, with major roles in neuroendocrine control, autonomic regulation, and stress responses.

Parietal arteries

The term parietal arteries usually refers to branches of major arteries that supply the walls of the cranial vault, thorax, or abdomen, depending on context. In neuroanatomy, it often refers to branches of the middle meningeal artery that supply the parietal bone.

Parietal bone

The parietal bone is a paired, flat cranial bone forming the superolateral walls and roof of the cranial vault. It plays a key role in protecting the brain and providing attachment for muscles of the scalp.

Parietal branches of superficial temporal artery and vein

The parietal branches of the superficial temporal artery and vein supply the temporal and parietal regions of the scalp and run along the lateral aspect of the skull.

Parietal emissary vein

The parietal emissary vein is one of the emissary veins of the skull that connects extracranial veins of the scalp with intracranial venous sinuses, allowing venous blood to bypass the deep venous system.

Parietal foramen (for emissary vein)

The parietal foramen is a small, variable opening in the posterior part of the parietal bone that allows passage of the parietal emissary vein, connecting the extracranial venous system with the superior sagittal sinus.

Parietal lobe

The parietal lobe is a major division of the cerebral cortex, located posterior to the frontal lobe and superior to the temporal lobe, involved in sensory processing, spatial awareness, and integration of information.

Parietal operculum

The parietal operculum is a portion of the parietal lobe that covers the insula, forming part of the lateral sulcus (Sylvian fissure) roof, and plays a role in somatosensory and multisensory integration.

Parietooccipital branch

The parietooccipital branch generally refers to a branch of the posterior cerebral artery (PCA) that supplies the medial surfaces of the parietal and occipital lobes along the parieto-occipital sulcus.

Parietooccipital sulcus

The parieto-occipital sulcus (POS) is a deep groove on the medial surface of the cerebral hemisphere that separates the parietal lobe from the occipital lobe. It is an important anatomical and functional landmark in neuroimaging and neuroanatomy.

Parotid branches of mandibular nerve

The mandibular nerve (V3) is the third division of the trigeminal nerve, which is both sensory and motor. Some of its parotid branches are sensory fibers that innervate the parotid gland region, and others are involved in autonomic innervation via the auriculotemporal nerve.

Parotid duct

The parotid duct, also known as Stensen’s duct, is the main excretory duct of the parotid gland, responsible for conveying saliva from the parotid gland into the oral cavity.

Parotid fascia

The parotid fascia is a dense connective tissue layer that envelops the parotid gland, providing protection, structural support, and anchoring to surrounding structures.

Parotid gland

The parotid gland is the largest of the major salivary glands, located in the parotid region of the face, and is primarily a serous (watery) gland that secretes saliva into the oral cavity via the parotid (Stensen’s) duct.

Parotid papilla with opening of parotid duct

The parotid papilla is a small mucosal elevation in the oral cavity that marks the opening of the parotid (Stensen’s) duct, allowing saliva from the parotid gland to enter the mouth.

Pars distalis

The pars distalis is the largest and most anterior portion of the anterior pituitary gland (adenohypophysis), responsible for secreting the majority of pituitary hormones.

Pars flaccida

The pars flaccida is a small, slack, superior portion of the tympanic membrane (eardrum) that differs from the tense pars tensa and plays a role in pressure regulation within the middle ear.

Pars intermedia

The pars intermedia is a narrow intermediate zone of the anterior pituitary (adenohypophysis), located between the pars distalis and pars nervosa (posterior pituitary), and is mostly rudimentary in humans.

Pars tensa

The pars tensa is the tense, main part of the eardrum (tympanic membrane).

Pars tuberalis

The pars tuberalis is a part of the pituitary gland (hypophysis), specifically of the anterior pituitary (adenohypophysis).

Pectinate ligament

The pectinate ligament is an anatomical structure in the eye, specifically related to the anterior chamber angle and trabecular meshwork, which are important for aqueous humor drainage.

Pectoralis major fascia

The pectoralis major fascia is a layer of connective tissue associated with the pectoralis major muscle in the chest.

Pectoralis major muscle

The pectoralis major is a large, fan-shaped muscle of the anterior chest wall that plays a major role in movements of the shoulder joint.

Pedicle

The term “pedicle” is used in anatomy to describe a stalk-like or stem-like structure that connects one part of the body to another or supports a structure. Its precise meaning depends on the context.

Pericallosal artery

The pericallosal artery is an important branch of the anterior cerebral artery (ACA) that runs along the corpus callosum.

Pericardium

The pericardium is the membranous sac that surrounds the heart and the roots of the great vessels, providing protection, lubrication, and mechanical support.

Perichoroidal space

The perichoroidal space is an anatomical space in the eye, located around the choroid, which is part of the uveal tract.

Pericranium

The pericranium is the periosteum of the outer surface of the skull bones, essentially a fibrous membrane covering the cranial bones.

Periglomerular cell

A periglomerular cell is a type of interneuron in the olfactory bulb involved in modulating sensory input from the nose.

Periodontium

The periodontium is the supporting structure of the teeth that anchors them to the jawbone and maintains their proper position.

Periorbita

The periorbita is the periosteum (fibrous membrane) lining the bones of the eye socket (orbit).

Periphery

The term “periphery” generally refers to the outer boundary or edge of a structure or area, as opposed to its center. Its precise meaning depends on context, such as anatomy, neurology, or medicine.

Perpendicular plate of ethmoid bone

The perpendicular plate of the ethmoid bone is a thin, vertical bony structure that forms the upper part of the nasal septum, dividing the nasal cavity into left and right halves.

Pes hippocampi

The pes hippocampi (Latin for “foot of the hippocampus”) is a structural part of the hippocampus in the brain, located in the medial temporal lobe.

Petrosal vein

The petrosal vein is an important venous structure in the posterior cranial fossa, involved in the drainage of blood from the brain.

Petrosquamous fissure of temporal bone

The petrosquamous fissure is a cleft or groove between the petrous and squamous parts of the temporal bone.

Petrotympanic fissure of temporal bone

The petrotympanic fissure (also called Glaserian fissure) is a narrow slit in the temporal bone connecting the middle ear cavity with the temporomandibular joint (TMJ) region and infratemporal fossa.

Petrous part (mastoid process absent) of temporal bone

The petrous part of the temporal bone is a pyramidal, dense portion of the temporal bone that houses the inner ear structures. When we specify “mastoid process absent,” we are focusing purely on the petrous portion, not including the lateral mastoid extension.

Petrous part of temporal bone

The petrous part of the temporal bone is a dense, pyramid-shaped portion of the temporal bone that forms part of the cranial base and houses the inner ear.

Petrotympanic fissure

The petrotympanic fissure is an anatomical feature of the temporal bone associated with the middle ear and temporomandibular joint (TMJ).

Pharyngeal

The term “pharyngeal” refers to anything related to the pharynx, which is a muscular tube connecting the nasal cavity, oral cavity, and larynx to the esophagus.

Pharyngeal aponeurosis

The pharyngeal aponeurosis is an important connective tissue structure in the pharynx that provides support and serves as an attachment for muscles.

Pharyngeal artery

The pharyngeal artery generally refers to branches of arteries that supply the pharynx, most commonly the ascending pharyngeal artery.

Pharyngeal branch of ascending pharyngeal artery

The pharyngeal branch of the ascending pharyngeal artery is a specific branch that supplies the pharynx.

Pharyngeal branch of glossopharyngeal nerve

The pharyngeal branch of the glossopharyngeal nerve (cranial nerve IX) is a small branch that contributes to the pharyngeal plexus and participates in the motor and sensory innervation of the pharynx.

Pharyngeal branch of maxillary nerve (V2)

The pharyngeal branch of the maxillary nerve is a small sensory branch of the maxillary division of the trigeminal nerve (CN V2) that supplies part of the nasopharynx.

Pharyngeal branch of pterygopalatine ganglion

The pharyngeal branch of the pterygopalatine ganglion is a small nerve that provides sensory fibers to the nasopharynx and adjacent structures.

Pharyngeal branch of vagus nerve

The pharyngeal branch of the vagus nerve (cranial nerve X) is a motor branch that contributes to the pharyngeal plexus, providing most of the motor innervation to the pharyngeal muscles.

Pharyngeal constrictor muscles

The pharyngeal constrictor muscles are a group of skeletal muscles forming the circular walls of the pharynx that play a key role in swallowing (deglutition).

Pharyngeal nerve

The term “pharyngeal nerve” can refer to small nerves that contribute to the pharyngeal plexus, but its precise identity depends on the cranial nerve it branches from.

Pharyngeal opening

A pharyngeal opening is an anatomical orifice that communicates with the pharynx, allowing passage of air, food, or connecting structures.

Pharyngeal opening of auditory (pharyngotympanic, Eustachian) tube

The pharyngeal opening of the auditory tube (also called the pharyngotympanic or Eustachian tube opening) is a key anatomical structure connecting the nasopharynx to the middle ear.

Pharyngeal plexus

The pharyngeal plexus is a network of nerves on the lateral wall of the pharynx that coordinates motor and sensory innervation of the pharynx and soft palate.

Pharyngeal plexus composed of branches from glossopharyngeal (IX) , vagus (X), and sympathetic nerves

The pharyngeal plexus is a nerve network on the lateral pharyngeal wall formed by contributions from the glossopharyngeal nerve (CN IX), vagus nerve (CN X), and sympathetic fibers.

Pharyngeal raphe

The pharyngeal raphe is an important fibrous midline structure of the pharynx that serves as an attachment for the pharyngeal constrictor muscles.

Pharyngeal recess

The pharyngeal recess (also called Rosenmüller’s fossa) is a clinically important anatomical feature of the nasopharynx.

Pharyngeal tonsil

The pharyngeal tonsil is a key lymphoid structure located in the nasopharynx, playing an important role in immune defense.

Pharyngeal tubercle

The pharyngeal tubercle is an important bony landmark on the occipital bone that serves as an attachment for the pharyngeal raphe.

Pharyngobasilar fascia

The pharyngobasilar fascia is a fibrous sheet lining the inner surface of the pharyngeal wall, deep to the pharyngeal constrictor muscles.

Pharyngoepiglottic fold

The pharyngoepiglottic fold is a mucosal fold in the oropharyngeal and laryngopharyngeal region that serves as an anatomical landmark and pathway for structures entering the laryngeal inlet.

Pharyngotympanic (auditory) tube

The pharyngotympanic tube—also called the auditory tube or Eustachian tube—is a canal connecting the middle ear to the nasopharynx, allowing air pressure equalization and drainage of secretions.

Pharynx

The pharynx is a musculomembranous tube connecting the nasal and oral cavities to the larynx and esophagus, serving as a common passageway for air and food.

Pharyngeal branch of vagus nerve

The pharyngeal branch of the vagus nerve (CN X) is a motor branch that primarily contributes to the pharyngeal plexus, providing most of the motor innervation to the pharynx and soft palate.

Philtrum of lip

The philtrum is the vertical groove located in the midline of the upper lip, extending from the nasal septum (base of the nose) to the vermilion border of the upper lip.

Phrenic nerve

The phrenic nerve is a mixed motor and sensory nerve that supplies the diaphragm, pericardium, and parts of the pleura and peritoneum.

Pia mater

The pia mater is a thin, delicate, highly vascularized connective tissue layer that adheres tightly to the surface of the brain and spinal cord, following every sulcus and gyrus.

Pigment cells

Pigment cells are specialized cells responsible for the synthesis and storage of pigments, mainly melanin, which gives color to tissues such as the skin, hair, eyes, and certain parts of the nervous system.

Pigment epithelium (iridial part of retina)

The pigment epithelium of the iridial part of the retina is a layer of pigmented cells in the anterior portion of the eye, playing roles in light absorption and ocular support.

Pillar (rod) cells

Pillar cells, also called rod cells, are specialized supporting cells in the organ of Corti of the cochlea. They play a structural role in hearing rather than directly detecting sound.

Pineal body

The pineal body, also called the pineal gland, is a small endocrine gland in the brain involved in regulating biological rhythms and producing melatonin.

Pineal recess

The pineal recess (also called the recessus pinealis) is a narrow posterior extension of the third ventricle into the area of the pineal gland.

Piriform fossa (recess)

A paired recess in the hypopharynx, lateral to the laryngeal inlet, directing food and liquids around the airway into the esophagus.

Piriform lobe

The piriform lobe is part of the paleocortex, located on the inferior (ventral) surface of the temporal lobe, involved in processing olfactory information.

Pituitary gland

The pituitary gland, also known as the hypophysis, is a small endocrine gland at the base of the brain that plays a central role in regulating growth, metabolism, reproduction, and other hormonal functions.

Plane of anterior semicircular canal

The anterior semicircular canal (also called the superior semicircular canal) is one of the three semicircular canals of the vestibular apparatus in the inner ear. Its plane is the geometric orientation in which it detects rotational movements of the head, specifically in the sagittal plane (nodding motion).

Plane of posterior semicircular canal

The posterior semicircular canal is one of the three semicircular canals in the vestibular apparatus of the inner ear. Its plane indicates the orientation in which it senses angular acceleration, particularly in the coronal plane (tilting the head toward the shoulders).

Platysma muscle

The platysma is a broad, superficial, subcutaneous muscle of the anterior and lateral neck. It is classified as a muscle of facial expression despite its location in the neck because it inserts into the lower face.

Plica semilunaris

The plica semilunaris is a crescent-shaped fold of bulbar conjunctiva located at the medial canthus of the eye. It is considered a vestigial remnant of the nictitating membrane (“third eyelid”) found in some animals.

Polar frontal artery

The polar frontal artery is a branch of the anterior cerebral artery (ACA) that specifically supplies the frontal pole, the most anterior part of the frontal lobe.

Polar temporal artery

The polar temporal artery is another cortical branch of the anterior cerebral artery (ACA), but it supplies the temporal pole rather than the frontal pole.

Pons

The pons is a part of the brainstem that acts as a bridge between different parts of the nervous system.

Pontine arteries

The pontine arteries are the small branches of the basilar artery that supply the pons, an essential part of the brainstem.

Pontine artery

The pontine arteries (or a singular pontine artery) are branches of the basilar artery that supply the pons, the central part of the brainstem.

Pontine taste area

The pontine taste area refers to the region in the pons (specifically in the rostral part of the solitary tract nucleus and adjacent structures) that processes taste (gustatory) information.

Posterior meningeal branch of left ascending pharyngeal artery

The posterior meningeal branch of the ascending pharyngeal artery (APA) is a small artery that supplies part of the dura mater of the posterior cranial fossa.

Postcentral gyrus

The postcentral gyrus is a prominent structure in the parietal lobe of the brain, primarily involved in somatosensory processing.

Postcentral sulcus

The postcentral sulcus is an important anatomical landmark in the parietal lobe of the brain, lying just posterior to the postcentral gyrus.

Postequatorial zonular fibers

The postequatorial zonular fibers are part of the zonule of Zinn, the system of fibers (suspensory ligaments) that hold the lens in place in the eye.

Posterior (dorsal) nucleus of vagus nerve

The posterior (dorsal) nucleus of the vagus nerve—often called the dorsal motor nucleus of the vagus (DMNV)—is a key brainstem nucleus involved in parasympathetic autonomic control.

Posterior arch

The term “posterior arch” can refer to different anatomical structures depending on context, but most commonly it refers to the posterior arch of a vertebra.

Posterior articular facet (for transverse ligament of atlas)

The posterior articular facet for the transverse ligament of the atlas is a small but important anatomical structure on the atlas (C1 vertebra).

Posterior articular facet of dens (for transverse ligament of atlas)

The posterior articular facet of the dens (odontoid process) for the transverse ligament of the atlas is a small smooth surface on the dens (C2 axis) that interacts with the transverse ligament of the atlas (C1).

Posterior atlantooccipital membrane

The posterior atlantooccipital membrane (PAOM) is a ligamentous structure connecting the atlas (C1) to the occipital bone at the base of the skull.

Posterior auricular artery

The posterior auricular artery is a branch of the external carotid artery that supplies structures around the ear and posterior scalp.

Posterior auricular nerve

The posterior auricular nerve is a branch of the facial nerve (cranial nerve VII) that primarily supplies muscles and skin posterior to the ear.

Posterior auricular vein

The posterior auricular vein is a venous structure that drains blood from the scalp and auricular region into the larger venous system of the head and neck.

Posterior belly

The term “posterior belly” usually refers to the posterior belly of the digastric muscle, but it can also apply to other muscles with anterior and posterior bellies.

Posterior border of thyroid cartilage lamina

The posterior border of the thyroid cartilage lamina is an anatomical feature of the thyroid cartilage, which is the largest cartilage of the larynx.

Posterior cerebellar notch

The posterior cerebellar notch is an anatomical feature of the occipital bone at the base of the skull.

Posterior cerebral artery

The posterior cerebral artery (PCA) is a major artery of the brain that supplies the occipital lobe, inferomedial temporal lobe, and parts of the thalamus and midbrain.

Posterior chamber of eye

The posterior chamber is a small, fluid-filled space in the eye, part of the anterior segment, located behind the iris and in front of the lens.

Posterior ciliary arteries

The posterior ciliary arteries are branches of the ophthalmic artery that supply the choroid, optic nerve head, and parts of the ciliary body and iris. They are crucial vessels for maintaining retinal and optic nerve perfusion.

Posterior clinoid process of sella turcica of sphenoid bone

The posterior clinoid processes are bony projections on the sphenoid bone that form part of the boundaries of the sella turcica and the clivus region. They play an important role in cranial anatomy, dural attachments, and neurosurgical landmarks.

Posterior cochlear nuclei

The posterior cochlear nucleus (also called the dorsal cochlear nucleus, DCN) is one of the two major subdivisions of the cochlear nuclei, located in the brainstem at the pontomedullary junction. It plays an essential role in early auditory processing, especially for sound localization, spectral (frequency) analysis, and complex sound processing.

Posterior commissure

The posterior commissure is a small but important bundle of white-matter fibers located in the dorsal midline of the upper brainstem, just above the cerebral aqueduct and below the pineal gland.

Posterior communicating artery

The posterior communicating artery (PCoA) is a key vessel of the circle of Willis that connects the internal carotid artery (ICA) to the posterior cerebral artery (PCA). It plays an essential role in maintaining collateral cerebral circulation.

Posterior conjunctival artery and vein

The posterior conjunctival vessels are small arterial and venous branches that supply the bulbar conjunctiva, especially the posterior (proximal) portion near the limbus.

Posterior cranial fossa

The posterior cranial fossa is the deepest and most posterior of the three cranial fossae. It houses the hindbrain structures and is formed by the occipital bone, parts of the temporal bone, and the sphenoid.

Posterior cricoarytenoid muscle

The posterior cricoarytenoid muscle is one of the intrinsic muscles of the larynx and plays a critical role in breathing.

Posterior deep temporal arteries

The posterior deep temporal arteries are important muscular branches of the maxillary artery that supply the deep surface of the temporalis muscle.

Posterior deep temporal nerves

The posterior deep temporal nerves are motor branches of the mandibular nerve (V3) that innervate the posterior fibers of the temporalis muscle, a major muscle of mastication.

Posterior division

The term “posterior division” generally refers to a division of a nerve trunk that gives rise to specific branches supplying certain muscles or regions. Its exact meaning depends on the context (e.g., brachial plexus, mandibular nerve, etc.).

Posterior ethmoidal artery

The posterior ethmoidal artery is a small but important branch of the ophthalmic artery, supplying parts of the ethmoid sinus, sphenoid sinus, and dura.

Posterior ethmoidal foramen

The posterior ethmoidal foramen is a small anatomical opening in the medial wall of the orbit that transmits the posterior ethmoidal artery, vein, and nerve.

Posterior ethmoidal nerve of ophthalmic nerve

The posterior ethmoidal nerve is a small branch of the nasociliary nerve (V1) that supplies sensory innervation to the posterior ethmoid air cells, sphenoid sinus, and parts of the dura in the anterior cranial fossa.

Posterior ethmoidal vein of posterior ethmoidal foramen

The posterior ethmoidal vein is a small venous channel that accompanies the posterior ethmoidal artery and nerve through the posterior ethmoidal foramen. It plays a role in venous drainage of the posterior ethmoid cells and sphenoid sinus into the orbital venous system.

Posterior fontanelle

The posterior fontanelle is a soft membranous gap in the skull of a newborn located at the junction of the sagittal and lambdoid sutures. It is one of the major cranial fontanelles, which allow for skull flexibility during birth and brain growth after birth.

Posterior inferior cerebellar artery

The posterior inferior cerebellar artery (PICA) is a major branch of the vertebral artery that supplies the posterior and inferior aspects of the cerebellum as well as parts of the medulla oblongata. It is a critical vessel in posterior circulation of the brain.

Posterior inferior lateral nasal branch from greater palatine nerve (V2)

The posterior inferior lateral nasal branch of the greater palatine nerve (V2) is a sensory branch of the maxillary division of the trigeminal nerve that supplies parts of the lateral wall of the nasal cavity.

Posterior intercostal artery

The posterior intercostal arteries are paired arteries that supply the intercostal spaces, thoracic wall, and some thoracic viscera, arising mainly from the thoracic aorta.

Posterior lateral choroidal artery

The posterior lateral choroidal artery (PLChA) is a branch of the posterior cerebral artery (PCA) that supplies deep structures of the brain, particularly parts of the lateral ventricle, choroid plexus, and thalamus.

Posterior lateral nasal branch

Posterior lateral nasal branches of sphenopalatine artery

The posterior lateral nasal branches of the sphenopalatine artery are small arterial branches that supply the lateral wall of the nasal cavity, particularly the posterior and inferior regions. They are clinically important in epistaxis and nasal surgery.

Posterior lateral nasal nerves

The posterior lateral nasal nerves are sensory branches of the pterygopalatine ganglion (CN V2 pathway) that supply the lateral wall of the nasal cavity, especially its posteroinferior part.

Posterior lateral superficial cervical (spinal accessory) nodes

The posterior lateral superficial cervical lymph nodes are a group of lymph nodes located along the posterior border of the sternocleidomastoid muscle, associated with the spinal accessory nerve (CN XI). They are part of the superficial cervical lymphatic chain.

Posterior ligament of incus

The posterior ligament of the incus is a small but important suspensory ligament in the middle ear that helps stabilize the incus, one of the three auditory ossicles.

Posterior limb of internal capsule

The posterior limb of the internal capsule is a major white matter tract in the brain that contains both ascending sensory fibers and descending motor fibers, connecting the cerebral cortex with the brainstem and spinal cord. It is a critical structure for motor and sensory function.

Posterior limiting lamina (Descemet's membrane)

The posterior limiting lamina—more commonly known as Descemet’s membrane—is the basement membrane of the corneal endothelium and one of the five major layers of the cornea.

Posterior lobe of cerebellum

The posterior lobe of the cerebellum is the largest and most functionally diverse of the three major cerebellar lobes. It plays a key role in coordination of voluntary movements, motor planning, and aspects of cognition and emotion.

Posterior longitudinal ligament

The posterior longitudinal ligament (PLL) is one of the major stabilizing ligaments of the vertebral column. It runs along the posterior surfaces of the vertebral bodies inside the vertebral canal, immediately anterior to the spinal cord.

Posterior mallear fold

The posterior mallear fold (also called the posterior malleolar fold) is a small mucosal fold in the tympanic membrane region that helps define the attachment of the malleus to the eardrum.

Posterior medial choroidal artery

The posterior medial choroidal artery is a paired branch of the posterior cerebral artery (PCA), typically arising from the P1 segment (the portion between the basilar bifurcation and the posterior communicating artery).

Posterior medial choroidal artery to choroid plexus of 3rd ventricle

The posterior medial choroidal artery (PMChA) is one of the principal arterial suppliers to the choroid plexus of the third ventricle.

Posterior medial frontal branches

Posterior medial frontal branches are cortical branches of the anterior cerebral artery (ACA) that supply the posterior part of the medial surface of the frontal lobe.

Posterior meningeal artery of jugular foramen

The posterior meningeal artery is a meningeal branch of the ascending pharyngeal artery that enters the cranium through the jugular foramen.

Posterior membranous ampulla

Posterior membranous ampulla refers to the expanded, dilated end of the posterior semicircular duct within the membranous labyrinth of the inner ear.

Posterior meningeal artery of mastoid foramen

The posterior meningeal artery of the mastoid foramen is a meningeal branch associated with the posterior cranial fossa.

Posterior meningeal branch of vertebral artery

The posterior meningeal branch of the vertebral artery is a small but clinically relevant artery that supplies the dura mater in the posterior cranial fossa.

Posterior mesencephalic vein

The posterior mesencephalic vein is a vein of the midbrain region involved in the drainage of the dorsal aspect of the mesencephalon.

Posterior nasal nerves

The posterior nasal nerves are sensory branches of the pterygopalatine ganglion that supply the nasal cavity, particularly the posterior and inferior parts of the nasal mucosa.

Posterior nasal spine of palatine bone

The posterior nasal spine (PNS) is an important bony landmark of the palatine bone in the skull.

Posterior nuclei of hypothalamus

The posterior nuclei of the hypothalamus are a group of hypothalamic nuclei located in the posterior region of the hypothalamus, mainly involved in autonomic and thermoregulatory functions.

Posterior nucleus of vagus nerve (parasympathetic and visceral afferent)

The posterior nucleus of the vagus nerve is more commonly referred to as the dorsal motor nucleus of the vagus (DMV) when describing parasympathetic function, and the nucleus of the solitary tract (NTS) when describing visceral afferent input.

Posterior of cerebellomedullary cistern

The posterior part of the cerebellomedullary cistern refers to the dorsal portion of the cisterna magna, the largest subarachnoid cistern of the posterior cranial fossa.

Posterior of tongue

The posterior part of the tongue refers to the root of the tongue, which is anatomically, functionally, and clinically distinct from the anterior two-thirds.

Posterior parietal artery

The posterior parietal artery is a branch of the middle cerebral artery (MCA) that supplies the posterior portion of the parietal lobe of the brain.

Posterior perforated substance

The posterior perforated substance is a key anatomical structure in the midbrain region, part of the floor of the third ventricle and interpeduncular fossa.

Posterior perforated substance (in interpeduncular fossa)

The posterior perforated substance (PPS) is a vascularly “perforated” area in the floor of the interpeduncular fossa, serving as an important landmark in the midbrain region.

Posterior ramus of lateral sulcus (of Sylvius)

The posterior ramus of the lateral sulcus (Sylvian fissure) is a branch of the lateral sulcus that extends toward the parietal and occipital lobes.

Posterior scalene muscles

The posterior scalene muscles are one of the three scalene muscles in the lateral neck, located posteriorly. They are important in respiration, neck movement, and as anatomical landmarks.

Posterior semicircular canals

The posterior semicircular canals are part of the vestibular system in the inner ear, responsible for detecting rotational movements of the head in the sagittal plane.

Posterior semicircular duct

The posterior semicircular duct is the membranous labyrinth counterpart of the posterior semicircular canal in the inner ear.

Posterior septal branch of sphenopalatine artery

The posterior septal branch of the sphenopalatine artery is an important terminal branch of the maxillary artery supplying the posterior part of the nasal septum.

Posterior spinal artery

The posterior spinal artery (PSA) is one of the main arteries supplying the posterior (dorsal) portion of the spinal cord.

Posterior spinal vein

The posterior spinal veins are part of the venous drainage system of the spinal cord, running along its dorsal aspect.

Posterior superior alveolar arteries

The posterior superior alveolar arteries (PSA arteries) are branches of the maxillary artery that supply the posterior maxillary teeth, sinus, and adjacent structures.

Posterior superior alveolar nerves

The posterior superior alveolar nerves (PSA nerves) are branches of the maxillary nerve (V2) that provide sensory innervation to the posterior maxillary teeth, sinus, and adjacent structures.

Posterior superior alveolar veins

The posterior superior alveolar veins (PSA veins) are the venous counterparts of the posterior superior alveolar arteries, responsible for draining the posterior maxillary teeth, alveolar bone, and maxillary sinus.

Posterior superior and inferior lateral nasal nerves

The posterior superior and posterior inferior lateral nasal nerves are branches of the pterygopalatine (sphenopalatine) ganglion, which is associated with the maxillary nerve (V2). They provide sensory and autonomic innervation to the lateral wall of the nasal cavity.

Posterior superior lateral nasal branch of maxillary nerve (V2)

The posterior superior lateral nasal branch of the maxillary nerve (V2) is a sensory nerve that supplies the superior and posterior part of the lateral wall of the nasal cavity.

Posterior temporal branches

The posterior temporal branches are usually branches of the superficial temporal artery or the middle temporal artery, supplying the posterolateral aspect of the temporal region. They can also refer to nerve branches (temporal branches of the facial nerve), but in vascular anatomy, they typically mean arterial branches.

Posterior temporal diploic vein

The posterior temporal diploic vein is one of the diploic veins that drain the spongy bone (diploë) of the cranial vault in the temporal region.

Posterior terminal vein of caudate nucleus

The posterior terminal vein of the caudate nucleus is a deep cerebral vein involved in draining the caudate nucleus and adjacent structures into the internal cerebral venous system.

Posterior tributaries of a vorticose vein

The posterior tributaries of a vorticose vein are the veins that drain the posterior part of the retina and empty into one of the vorticose (vortex) veins, which then exit the eye through the sclera.

Posterior tubercle

The term posterior tubercle appears in multiple anatomical contexts, but generally, it refers to a small bony projection located on the posterior aspect of a bone or vertebra.

Posterior tubercle of transverse process

The posterior tubercle of the transverse process is a small bony prominence on the posterior aspect of the transverse process of a vertebra, most commonly described in cervical vertebrae.

Posterior tubercle of transverse process of axis (C2)

The posterior tubercle of the transverse process of the axis (C2) is a small bony prominence on the posterior aspect of C2’s transverse process. It serves as an important site for muscle and ligament attachment in the cervical region.

Posterior tubercle of transverse process of C7 vertebra

The posterior tubercle of the transverse process of C7 is a small bony prominence on the posterior aspect of the transverse process of the seventh cervical vertebra. It is anatomically and functionally important as a muscle and ligament attachment site.

Posterior tubercles of transverse process of C3 vertebra

The posterior tubercles of the transverse process of C3 are small bony projections on the posterior aspect of the transverse processes of the third cervical vertebra. They serve as important sites for muscle and ligament attachment in the cervical spine.

Posterior vein of caudate nucleus

The posterior vein of the caudate nucleus is a deep cerebral vein that drains the posterior portion of the caudate nucleus into the internal cerebral venous system.

Posterior veins of septum pellucidum

The posterior veins of the septum pellucidum are small cerebral veins that drain the posterior part of the septum pellucidum into the internal cerebral venous system.

Posterior wall of pharynx

The posterior wall of the pharynx is the back boundary of the pharyngeal space, extending from the base of the skull down to the esophagus. It provides structural support, muscular attachments, and a pathway for swallowing.

Posterolateral (dorsolateral) fissure of flocculonodular lobe of cerebellum

The posterolateral (dorsolateral) fissure is a major cerebellar fissure that separates the flocculonodular lobe from the rest of the cerebellum (specifically the posterior lobe).

Posteromedial central (paramedian) arteries

The posteromedial central (paramedian) arteries are small penetrating arteries arising from the basilar or vertebral arteries that supply the medial portions of the brainstem, particularly the pons and medulla.

Posteromedial central (perforating) arteries

The posteromedial central (perforating) arteries are small penetrating arteries that arise from the basilar or vertebral arteries and supply the medial portions of the brainstem, particularly the pons and medulla. These are sometimes called paramedian perforating arteries.

Postganglionic parasympathetic fibers

Postganglionic parasympathetic fibers are the second-order neurons of the parasympathetic nervous system that transmit signals from parasympathetic ganglia to target organs.

Postganglionic sympathetic fibers

Postganglionic sympathetic fibers are the second-order neurons of the sympathetic nervous system that transmit signals from sympathetic ganglia to target organs. They are usually longer than parasympathetic postganglionic fibers because sympathetic preganglionic fibers often synapse in the paravertebral (sympathetic chain) or prevertebral ganglia far from the target organs.

Postlunate fissure of posterior lobe of cerebellum

The postlunate fissure is a deep cerebellar fissure located in the posterior lobe of the cerebellum, separating specific lobules of the cerebellar hemisphere.

Postsynaptic fibers to vessels (sympathetic) and glands (parasympathetic) of nasal cavity, maxillary sinus, and palate

The postsynaptic fibers to vessels (sympathetic) and glands (parasympathetic) of the nasal cavity, maxillary sinus, and palate are the second-order neurons that innervate these regions, providing autonomic control over blood flow and secretion.

Precentral arteries

The precentral arteries are small penetrating branches of the middle cerebral artery (MCA) that supply the precentral gyrus, which contains the primary motor cortex (Brodmann area 4).

Precentral cerebellar vein

The precentral cerebellar vein is a deep vein of the cerebellum that drains the anterior (precentral) region of the cerebellar hemispheres into the straight or great cerebral vein (of Galen) system.

Precentral gyrus

The precentral gyrus is the primary motor cortex of the brain, located in the frontal lobe immediately anterior to the central sulcus. It is responsible for voluntary motor control of the contralateral side of the body.

Precentral sulcal artery

The precentral sulcal artery is a branch of the middle cerebral artery (MCA) that supplies the precentral sulcus and adjacent precentral gyrus, which contains the primary motor cortex.

Precentral sulcus

The precentral sulcus is a prominent groove in the frontal lobe that lies immediately anterior to the precentral gyrus. It serves as an anatomical boundary between the primary motor cortex and premotor areas.

Prechiasmatic groove of body of sphenoid bone

The prechiasmatic groove (also called the chiasmatic sulcus) is a shallow groove on the superior surface of the body of the sphenoid bone that lies anterior to the sella turcica and supports the optic chiasm.

Preculminate vein

The preculminate vein is a cerebral vein of the occipital lobe that drains part of the precuneus and cuneus regions into the internal cerebral venous system.

Precuneal artery

The precuneal artery is a branch of the posterior cerebral artery (PCA) that supplies the precuneus, a part of the medial parietal lobe involved in visuospatial processing, self-reflection, and aspects of consciousness.

Precuneus

The precuneus is a medial parietal cortical region of the brain located in the superior part of the parietal lobe, tucked between the cingulate gyrus and the parieto-occipital sulcus. It is involved in higher-order cognitive functions, self-related processing, and visuospatial integration.

Preequatorial zonular fibers

The preequatorial zonular fibers are part of the zonular apparatus (suspensory ligament of the lens) in the eye, specifically the fibers located anterior to the lens equator. They play a crucial role in lens positioning and accommodation.

Prefrontal artery

The prefrontal artery is a branch of the anterior cerebral artery (ACA) that supplies the prefrontal cortex, a region of the frontal lobe involved in executive functions, personality, and planning.

Prefrontal sulcal artery

The prefrontal sulcal artery is a cortical branch of the anterior cerebral artery (ACA) that specifically supplies the prefrontal cortex along the superior and middle frontal gyri, following the prefrontal sulci.

Preganglionic parasympathetic fibers

Preganglionic parasympathetic fibers are the first-order neurons of the parasympathetic nervous system, which carry impulses from the central nervous system to parasympathetic ganglia. These fibers are long, myelinated, and terminate in ganglia where they synapse with postganglionic neurons.

Preganglionic sympathetic cell bodies in intermediolateral nucleus of gray matter

Preganglionic sympathetic cell bodies are the first-order neurons of the sympathetic nervous system whose cell bodies are located in the intermediolateral (IML) cell column of the spinal cord gray matter.

Preganglionic sympathetic fibers

Preganglionic sympathetic fibers are the first-order neurons of the sympathetic nervous system that carry impulses from the spinal cord to sympathetic ganglia. They are myelinated, relatively short fibers compared to their postganglionic counterparts.

Preoccipital notch

The preoccipital notch is a small indentation on the inferior border of the occipital lobe of the brain, serving as an important anatomical landmark in neuroimaging and neurosurgery.

Prepontine cistern

The prepontine cistern is one of the subarachnoid cisterns of the brain, located anterior to the pons, containing important neurovascular structures. It acts as a CSF-filled space that cushions and allows passage of cranial nerves and arteries.

Pretracheal (visceral) fascia

The pretracheal (visceral) fascia is a layer of deep cervical fascia in the neck that surrounds the visceral structures of the anterior neck.

Pretracheal layer of (deep) cervical fascia over thyroid gland and trachea

The pretracheal layer of deep cervical fascia is specifically the visceral fascia of the neck that covers the thyroid gland, trachea, and other anterior neck viscera.

Pretracheal lymph nodes

Pretracheal lymph nodes are part of the cervical lymphatic system, specifically associated with the anterior neck and trachea.

Prevertebral fascia

The prevertebral fascia is another important layer of the deep cervical fascia in the neck.

Primary fissure of anterior lobe of cerebellum

The primary fissure of the anterior lobe of the cerebellum is an important anatomical landmark used to divide parts of the cerebellum.

Primary plexus of hypophyseal portal system

The primary plexus of the hypophyseal portal system is the initial capillary network in the pituitary portal circulation that connects the hypothalamus to the anterior pituitary.

Principal nuclei of hypothalamus

The hypothalamus contains several principal (major) nuclei, each with specific functions in regulating autonomic, endocrine, and behavioral processes.

Principal sensory nucleus of trigeminal nerve

The principal sensory nucleus of the trigeminal nerve is one of the main sensory nuclei of cranial nerve V (trigeminal nerve).

Procerus muscle

The procerus is a small facial muscle of the glabellar region (between the eyebrows) that contributes to facial expression.

Prominence caused by greater horn of hyoid bone

The prominence caused by the greater horn of the hyoid bone refers to a palpable bony landmark in the lateral neck region.

Prominence caused by superior horn of thyroid cartilage

The prominence caused by the superior horn of the thyroid cartilage refers to a bony-cartilaginous landmark in the anterior neck.

Prominence of facial canal

The prominence of the facial canal refers to a bony landmark seen on the medial wall of the middle ear cavity, caused by the facial nerve (cranial nerve VII) as it passes through the temporal bone.

Prominence of lateral semicircular canal

The prominence of the lateral semicircular canal is a bony landmark seen on the lateral wall of the middle ear cavity, caused by the underlying lateral (horizontal) semicircular canal of the inner ear.

Prominence over lamina of cricoid cartilage

The prominence over the lamina of the cricoid cartilage refers to the posterior plate (lamina) of the cricoid cartilage in the larynx, which forms a palpable or visual landmark in certain views.

Promontory

The promontory is an important anatomical landmark in the middle ear, representing part of the bony cochlea of the inner ear.

Promontory with tympanic plexus

The promontory with tympanic plexus is an important anatomical structure in the middle ear, representing both a bony landmark and an overlying nerve network.

Pterion

The pterion is a region on the lateral side of the skull where four cranial bones meet.

Pterygoid fossa

The pterygoid fossa is an anatomical depression in the sphenoid bone that serves as a site of muscular attachment in the deep face.

Pterygoid fovea of lateral pterygoid

The pterygoid fovea is specifically the depression on the neck of the mandibular condyle where the lateral pterygoid muscle attaches.

Pterygoid hamulus of sphenoid bone

The pterygoid hamulus is a small hook-like projection of the medial pterygoid plate of the sphenoid bone.

Pterygoid plexus

The pterygoid venous plexus is an important network of veins in the infratemporal region, notable for its connections to the cavernous sinus and clinical significance in facial infections.

Pterygoid process

The pterygoid process is a part of the sphenoid bone in the skull and serves as an attachment site for important muscles of mastication and the soft palate.

Pterygomandibular raphe

The pterygomandibular raphe is a fibrous band in the oral-pharyngeal region that serves as a tendinous attachment for muscles of the cheek and pharynx.

Pterygomaxillary fissure

The pterygomaxillary fissure is a vertical gap or slit between the posterior aspect of the maxilla and the pterygoid process of the sphenoid bone.

Pterygopalatine fossa

The pterygopalatine fossa is a small but clinically important space in the deep face that serves as a neurovascular hub.

Pterygopalatine ganglia

The pterygopalatine ganglion is a major parasympathetic ganglion in the deep face, associated with the maxillary nerve (CN V2).

Pulmonary plexus

The pulmonary plexus is an important network of autonomic nerves that innervates the lungs and bronchi.

Pulvinar of thalamus

The pulvinar is a major structure of the thalamus in the brain, involved in visual, sensory, and associative processing.

Pupil

The pupil is the opening in the center of the iris that regulates the amount of light entering the eye.

Putamen of lentiform nucleus

The putamen is a key structure of the basal ganglia in the brain, specifically part of the lentiform (lenticular) nucleus.

Pyloric branch form hepatic plexus

The pyloric branch of the hepatic plexus is an autonomic nerve branch that innervates the pyloric region of the stomach.

Pyramid of inferior vermis

The pyramid of the inferior vermis is a part of the cerebellum, specifically within the vermal region of the posterior (inferior) lobe.

Pyramidal eminence

The pyramidal eminence is a conical bony projection on the posterior wall of the tympanic cavity.

Pyramidal lobe of thyroid gland

The pyramidal lobe is a small, conical extension of thyroid tissue arising from the isthmus or adjacent part of a thyroid lobe.

Pyramidal process of palatine bone

The pyramidal process of the palatine bone is a small but clinically important part of the palatine bone in the skull.

Quadrangular lobule of anterior lobe of cerebellum

The quadrangular lobule is a lobule of the anterior lobe of the cerebellum, located on the superior surface and forming part of the cerebellar hemispheres. It plays a role in coordination of voluntary movements, particularly of the limbs.

Quadrigeminal cistern (of great cerebral vein)

The quadrigeminal cistern (also called the cistern of the great cerebral vein) is a subarachnoid cistern located in the posterior part of the brain, overlying the tectal plate (quadrigeminal plate) of the midbrain. It contains important veins and arteries and serves as a CSF reservoir.

Radiograph

A radiograph is a diagnostic image produced using X-rays to visualize the internal structures of the body.

Rami communicantes

The rami communicantes are small nerve branches that connect spinal nerves to the sympathetic trunk, forming an essential part of the autonomic nervous system.

Ramus of mandible

The ramus of the mandible is the vertical part of the mandible that connects the body of the mandible to the temporomandibular region.

Recesses of maxillary sinus

The recesses of the maxillary sinus are anatomical extensions of the main maxillary sinus cavity into surrounding areas. They are important for sinus drainage, infection spread, and surgical anatomy.

Rectus capitis anterior muscle

The rectus capitis anterior muscle is a small prevertebral muscle in the upper neck that helps flex and stabilize the head at the atlanto-occipital joint.

Rectus capitis lateralis muscle

The rectus capitis lateralis muscle is another small, deep neck muscle involved in lateral flexion and stabilization of the head.

Recurrent branch of anterior ciliary artery

The recurrent branch of the anterior ciliary artery is a small arterial branch that runs backward from the anterior ciliary artery toward the root of the eye or orbit.

Recurrent laryngeal nerve (X)

The recurrent laryngeal nerve (RLN) is a critical branch of the vagus nerve (cranial nerve X) that innervates most of the intrinsic muscles of the larynx and provides sensory innervation to parts of the larynx and trachea.

Recurrent meningeal branch of lacrimal (ophthalmic) artery

The recurrent meningeal branch of the lacrimal artery is a small artery that connects the orbit to the anterior cranial fossa.

Recurrent process

The recurrent process is a small bony or cartilaginous projection that curves backward toward the main structure.

Red nucleus

The red nucleus is a paired structure in the rostral midbrain characterized by its reddish color due to high iron content in its neurons. It is a major motor relay nucleus in the rubrospinal system.

Reduplicated foramen transversarium

A reduplicated (double) foramen transversarium refers to the presence of an additional opening in the transverse process of a cervical vertebra, usually in C6 or C7. It is a congenital variant and not normally present in typical anatomy.

Reticular nucleus

The reticular nucleus of the thalamus is a thin layer of inhibitory neurons (GABAergic) that forms a capsule around the lateral aspect of the thalamus. It is considered part of the thalamic reticular formation and modulates the activity of other thalamic nuclei.

Retina

The retina is a light-sensitive layer at the back of the eye that is essential for vision, converting light into neural signals that the brain can interpret.

Retinal artery and vein

The retinal artery and vein are the primary blood vessels supplying and draining the inner layers of the retina, essential for retinal function and vision.

Retrobulbar fat (orbital fat body)

Retrobulbar fat (also called the orbital fat body) is the fat tissue located behind the eyeball within the orbit, providing cushioning, support, and mobility for the eye.

Retrolenticular part of internal capsule

The retrolenticular part of the internal capsule is a specific segment of the internal capsule in the brain, important in visual and auditory pathways.

Retromandibular

The term “retromandibular” generally refers to structures located behind the mandible. It is commonly used in reference to the retromandibular vein, retromandibular region, and retromandibular lymph nodes.

Retromandibular vein

The retromandibular vein is a major vein in the parotid and facial region, important for venous drainage of the face and scalp.

Retropharyngeal nodes

The retropharyngeal lymph nodes are deep cervical lymph nodes located posterior to the pharynx, important in lymphatic drainage of the head and neck.

Retropharyngeal space

The retropharyngeal space is a deep cervical fascial space located posterior to the pharynx and anterior to the prevertebral fascia, clinically important as a potential route for spread of infection from the head to the mediastinum.

Retrotonsillar fissure of flocculonodular lobe of cerebellum

The retrotonsillar fissure of the flocculonodular lobe of the cerebellum is a small anatomical cleft located just posterior to the cerebellar tonsil, near the flocculonodular lobe.

Revertebral layer of (deep) cervical fascia

The revertebral layer of the deep cervical fascia, also called the prevertebral fascia, is the posterior layer of the deep cervical fascia that lies in front of the cervical vertebrae and the deep muscles of the neck. It forms a tubular sheath around the vertebral column and associated muscles.

Rhinal sulcus

The rhinal sulcus is a shallow groove on the medial aspect of the cerebral hemisphere, located in the temporal lobe. It serves as an important landmark separating parts of the rhinencephalon (the olfactory brain) from the rest of the cerebral cortex.

Rhomboid fossa of 4th ventricle

The rhomboid fossa is the floor of the fourth ventricle in the brain. Its name comes from its diamond-shaped (rhomboid) appearance when viewed from the dorsal (posterior) surface of the brainstem.

Rib

A rib is a curved, flat bone that forms part of the thoracic cage, protecting the thoracic organs (heart, lungs) and assisting in respiration.

Right anterior cerebral artery

The right anterior cerebral artery (ACA) is one of the major arteries supplying the medial and superior aspects of the cerebral hemispheres, originating from the internal carotid artery.

Right bony labyrinth

The right bony labyrinth is the rigid, bony outer structure of the inner ear located within the petrous part of the temporal bone. It houses the membranous labyrinth, which contains the sensory organs for hearing and balance.

Right brachiocephalic vein

The right brachiocephalic vein is a large vein in the thorax that drains blood from the head, neck, and upper limb into the superior vena cava (SVC). It is formed by the union of the right internal jugular vein and right subclavian vein.

Right clavicle

The right clavicle is the S-shaped bone that forms the anterior part of the shoulder girdle on the right side of the body. It serves as a strut connecting the upper limb to the trunk and provides attachment for muscles and ligaments.

Right common carotid artery

The right common carotid artery (CCA) is a major artery that supplies blood to the head and neck on the right side of the body.

Right deep cervical vein

The right deep cervical vein is a deep vein of the neck that drains blood from the deep muscles of the posterior neck and communicates with the vertebral venous system. It runs alongside the deep cervical artery, which it accompanies.

Right dorsal branch to corpus callosum (posterior pericallosal artery)

The right dorsal branch to the corpus callosum, also called the posterior pericallosal artery, is a branch of the right anterior cerebral artery (ACA) that supplies the posterior portion of the corpus callosum and adjacent medial cerebral cortex.

Right external carotid artery

The right external carotid artery (ECA) is a major artery in the neck that supplies blood to the face, scalp, jaw, neck, and some cranial structures. It is a terminal branch of the common carotid artery (CCA) on the right side.

Right internal carotid artery

The right internal carotid artery (ICA) is a major artery of the head and neck that supplies blood to the brain, eyes, and other intracranial structures. It is one of the two terminal branches of the common carotid artery.

Right internal jugular vein (inferior bulb)

The right internal jugular vein (inferior bulb) is the dilated lower portion of the internal jugular vein where it joins the subclavian vein to form the brachiocephalic vein. This part is clinically and anatomically important because it helps facilitate venous return from the brain and can be involved in procedures like central venous catheterization.

Right lateral ventricle

The right lateral ventricle is one of the two largest cavities in the ventricular system of the brain, located within the cerebral hemispheres. It contains cerebrospinal fluid (CSF) and communicates with other ventricles to allow CSF circulation.

Right lobe of thyroid gland

The right lobe of the thyroid gland is one of the two main lobes of the thyroid gland, located on the right side of the neck. The thyroid is an endocrine gland responsible for producing thyroid hormones (T3 and T4) and calcitonin.

Right posterior cerebral artery

The right posterior cerebral artery (PCA) is one of the major arteries supplying the posterior part of the brain, particularly the occipital lobe, inferior temporal lobe, and parts of the thalamus and midbrain. It is a terminal branch of the basilar artery.

Right pulvinar

The right pulvinar is a part of the thalamus, specifically its posterior nucleus, located in the dorsal thalamus. It plays a key role in sensory integration, visual processing, and attention.

Right recurrent laryngeal nerve

The right recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that supplies motor innervation to most intrinsic muscles of the larynx and sensory innervation to parts of the larynx, trachea, and upper esophagus. Its course is asymmetrical on the right and left sides due to embryological development.

Right subclavian artery

The right subclavian artery is a major artery of the upper thorax and neck that supplies blood to the right upper limb, parts of the thorax, neck, and brain. It is the first major branch of the brachiocephalic artery on the right side.

Right subclavian artery

The right subclavian artery is a major artery that supplies the right upper limb, parts of the neck, thoracic wall, and posterior brain. It is the first branch of the brachiocephalic (innominate) artery on the right side.

Right subclavian vein

The right subclavian vein is a large vein of the upper thorax and lower neck that drains blood from the right upper limb, some of the thoracic wall, and portions of the head and neck into the brachiocephalic vein.

Right thyrocervical trunk

The right thyrocervical trunk is a short but important branch of the right subclavian artery that supplies blood to structures in the lower neck, upper thorax, and shoulder region.

Right vagus nerve (X)

The right vagus nerve (cranial nerve X) is a mixed cranial nerve that carries motor, sensory, and parasympathetic fibers, playing a critical role in autonomic control of the thoracic and abdominal organs, as well as motor and sensory functions of the larynx, pharynx, and viscera.

Right vertebral artery

The right vertebral artery is a major artery of the neck and posterior brain, supplying the posterior part of the brain, brainstem, and cervical spinal cord. It is one of the two vertebral arteries (right and left) that form the basilar artery.

Right vertebral vein

The right vertebral vein is a venous structure that drains blood from the cervical spinal cord, vertebrae, and posterior neck muscles into the brachiocephalic vein. It runs alongside the vertebral artery in the neck.

Risorius muscle

The risorius muscle is a thin, superficial facial muscle involved in facial expression, specifically in pulling the corner of the mouth laterally, contributing to smiling (usually a “grinning” expression).

Rods

In anatomy, rods (or rod cells) are one of the two main types of photoreceptor cells in the retina of the eye. They are specialized for vision in low light (scotopic vision) and peripheral vision, but do not detect color.

Root (central) canals containing vessels and nerves

The root (central) canals are microscopic channels located within teeth, specifically within the roots of a tooth, that house blood vessels, lymphatics, and nerves supplying the tooth. They are part of the pulp system.

Root of tongue

The root of the tongue is the posterior part of the tongue, located in the oropharynx, that anchors the tongue to the hyoid bone and pharyngeal structures. It is largely immobile and structurally distinct from the mobile anterior part of the tongue.

Root of tooth

The root of a tooth is the part of the tooth embedded in the alveolar bone that anchors the tooth firmly in its socket and contains the pulp canal with vessels and nerves. It lies below the gum line (gingiva) and is continuous with the crown via the neck of the tooth.

Roots of ciliary ganglion

The roots of the ciliary ganglion are the three nerve roots that enter the ciliary ganglion, each carrying different types of fibers (parasympathetic, sympathetic, and sensory) to the eye. The ciliary ganglion is a small parasympathetic ganglion located in the orbit, lateral to the optic nerve.

Rostrum of corpus callosum

The rostrum of the corpus callosum is the anterior, inferior part of the corpus callosum, which is the largest bundle of commissural fibers connecting the two cerebral hemispheres. The rostrum lies below the genu and curves posteroinferiorly toward the lamina terminalis.

Round (cochlear) window of temporal bone

The round (cochlear) window of the temporal bone is a membranous opening in the bony cochlea that allows communication between the middle ear and the inner ear, specifically the cochlea, and plays a key role in pressure relief for sound waves transmitted through the cochlea. It is also called the fenestra cochleae.

Saccule

The saccule is one of the two otolith organs of the vestibular system in the inner ear (the other is the utricle). Its primary function is to detect vertical linear acceleration and head position relative to gravity.

Sagittal suture

The sagittal suture is a fibrous, immovable (synarthrotic) joint that connects the right and left parietal bones of the skull.

Salivary glands

The salivary glands are exocrine glands in the head and neck that produce saliva, which is essential for lubricating food, beginning digestion, protecting oral tissues, and maintaining dental health.

Salpingopharyngeal fold

The salpingopharyngeal fold is a mucosal ridge in the nasopharynx that overlies the salpingopharyngeus muscle.

Salpingopharyngeus muscle

The salpingopharyngeus is a small longitudinal muscle of the pharynx that helps elevate the pharynx and open the auditory tube during swallowing.

Scala tympani of cochlea

The scala tympani is one of the three fluid-filled chambers of the cochlea in the inner ear. It plays a key role in hearing by transmitting sound-induced pressure waves.

Scala vestibuli of cochlea

The scala vestibuli is one of the three fluid-filled chambers of the cochlea and is crucial for transmitting sound vibrations in the process of hearing.

Scalene and prevertebral muscles

These are deep muscles of the neck located in the prevertebral region, and they play key roles in neck movement, stabilization, and respiration.

Scalp

The scalp is the soft tissue layer that covers the calvaria (skullcap) from the superciliary arches anteriorly to the external occipital protuberance and superior nuchal lines posteriorly, and laterally to the zygomatic arches.

Scaphoid fossa

The scaphoid fossa is a long, narrow, curved depression on the lateral surface of the auricle (pinna) of the external ear.

Scapula

The scapula, or shoulder blade, is a flat, triangular bone that forms the posterior part of the shoulder girdle. It connects the humerus (arm bone) with the clavicle (collarbone) and provides attachment points for multiple muscles involved in shoulder and arm movements.

Schematic stereogram

A schematic stereogram is a simplified diagrammatic representation of a stereoscopic structure or spatial arrangement, often used in anatomy, neuroanatomy, or optics to show three-dimensional relationships on a two-dimensional plane.

Schwalbe's line

Schwalbe’s line is an anatomical landmark in the anterior chamber of the eye, marking the termination of Descemet’s membrane and the junction between the corneal endothelium and the trabecular meshwork.

Sclera

The sclera is the white, opaque, fibrous outer layer of the eyeball that provides protection, shape, and structural support. It forms the posterior five-sixths of the outer tunic of the eye.

Scleral spur

The scleral spur is a circular ridge of scleral tissue located in the anterior chamber angle of the eye, serving as an important anatomical landmark and attachment site.

Scleral venous sinus (canal of Schlemm)

The scleral venous sinus, commonly called Canal of Schlemm, is a circular venous channel in the eye that plays a crucial role in draining aqueous humor from the anterior chamber into the venous system.

Sebaceous glands

Sebaceous glands are small exocrine glands in the skin that secrete sebum, an oily substance that lubricates and protects the skin and hair.

Secondary (postpyramidal) fissure of posterior lobe of cerebellum

The secondary (postpyramidal) fissure is a shallow groove on the superior surface of the posterior lobe of the cerebellum, part of the cerebellar foliation that separates different lobules.

Secondary plexus of hypophyseal portal system

The secondary plexus is a capillary network within the anterior pituitary (adenohypophysis) that is part of the hypophyseal portal system, which allows efficient transport of hypothalamic hormones to the anterior pituitary.

Segment of episcleral vein

The episcleral veins are part of the venous drainage system of the anterior eye, and the term “segment of episcleral vein” usually refers to individual portions or channels of this network that drain aqueous humor from Schlemm’s canal into the systemic venous circulation.

Sella turcica of Sphenoid bone

The sella turcica (“Turkish saddle”) is a saddle-shaped depression in the sphenoid bone of the skull that houses the pituitary gland (hypophysis). It is an important landmark in both anatomy and radiology.

Semicircular canals

The semicircular canals are three fluid-filled bony loops in the inner ear that are part of the vestibular apparatus, responsible for detecting rotational movements (angular acceleration) of the head.

Semicircular ducts

The semicircular ducts are the membranous structures within the bony semicircular canals of the inner ear. They are part of the vestibular apparatus and function as sensory organs for detecting rotational movement (angular acceleration) of the head.

Semilunar fold

The semilunar fold (also called the plica semilunaris) is a small crescent-shaped fold of conjunctiva located in the medial corner of the eye (near the inner canthus).

Semilunar hiatus

The semilunar hiatus is a curved groove in the lateral wall of the middle nasal meatus that serves as a key drainage pathway for the frontal, maxillary, and anterior ethmoidal sinuses.

Semilunar hiatus (osteomeatal unit)

The semilunar hiatus is a key anatomical groove in the lateral wall of the middle nasal meatus that forms a central part of the osteomeatal unit (OMU), which is the functional drainage area of the anterior paranasal sinuses.

Sensory root of ciliary ganglion

The ciliary ganglion is a small parasympathetic ganglion in the orbit that lies posterolateral to the optic nerve and is primarily associated with autonomic innervation to the eye. The sensory root is one of the three types of fibers entering the ganglion.

Sensory branches to larynx

The larynx receives sensory innervation from branches of the vagus nerve (cranial nerve X). These sensory branches convey general sensation, pain, and reflexes from the mucosa of the larynx.

Sensory cell

A sensory cell is a specialized cell that detects specific stimuli from the internal or external environment and converts them into electrical signals (receptor potentials) that can be transmitted to the nervous system for processing.

Sensory cortex

The sensory cortex is a region of the cerebral cortex responsible for processing sensory information from the body, including touch, pressure, pain, temperature, vibration, proprioception, and in some areas, taste, vision, and hearing.

Sensory root

A sensory root is the portion of a spinal or cranial nerve that carries afferent (sensory) fibers from the periphery toward the central nervous system. These fibers convey sensory information such as touch, pain, temperature, vibration, and proprioception.

Sensory root of ciliary ganglion (from nasociliary nerve)

The sensory root of the ciliary ganglion is a small branch that carries sensory fibers from the eye to the ciliary ganglion, specifically originating from the nasociliary nerve, which is a branch of the ophthalmic division (V1) of the trigeminal nerve (cranial nerve V).

Sensory root of ciliary ganglion of ophthalmic nerve (V1)

The sensory root of the ciliary ganglion of the ophthalmic nerve (V1) is a small branch that carries sensory fibers from the eye to the ciliary ganglion, but these fibers do not synapse in the ganglion.

Sensory root of trigeminal nerve

The sensory root of the trigeminal nerve (cranial nerve V) is one of the two roots of the trigeminal nerve—the other being the motor root.

Septal and lateral nasal branches of posterior ethmoidal artery

The posterior ethmoidal artery is a small branch of the ophthalmic artery, which supplies parts of the ethmoid and nasal region.

Septal area

In anatomy, the septal area usually refers to the nasal septum region of the nose.

Septal cartilage

The septal cartilage is the cartilaginous part of the nasal septum, forming the anterior and flexible portion of the structure that divides the nasal cavity into right and left halves.

Septum pellucidum

The septum pellucidum is a thin, transparent membrane in the brain that separates the lateral ventricles.

Serous

In anatomy, “serous” refers to a thin, watery fluid or the membrane that produces it, usually found in closed body cavities. It is derived from the Latin serum, meaning “whey” or “watery fluid.”

Short ciliary nerve of ophthalmic nerve

The short ciliary nerves are branches that carry autonomic and sensory fibers to the eye, primarily associated with the ciliary ganglion. They are related to the ophthalmic nerve (V1) via the nasociliary nerve.

Short gyri of insula (island of Reil)

The short gyri of the insula are a group of gyri located on the anterior part of the insular cortex (also called the Island of Reil).

Short hypophyseal portal veins

The short hypophyseal portal veins are part of the vascular system of the pituitary gland, specifically connecting the hypothalamus to the anterior pituitary (adenohypophysis).

Short limb of incus

The short limb of the incus is a part of one of the three ossicles of the middle ear (malleus, incus, stapes).

Short posterior ciliary arteries

The short posterior ciliary arteries (SPCAs) are branches of the ophthalmic artery that supply the posterior part of the eye.

Sigmoid sinus

The sigmoid sinus is a major venous sinus of the brain, part of the dural venous sinus system, that drains blood from the brain toward the internal jugular vein.

Sigmoid sinus of jugular foramen

The sigmoid sinus at the jugular foramen refers to the distal continuation of the sigmoid sinus as it exits the cranial cavity to become the internal jugular vein.

Simple lobule of anterior lobe of cerebellum

A simple lobule is one of the small structural subdivisions of the anterior lobe of the cerebellum.

Sinus of frontal bone

The sinus of the frontal bone refers to the frontal sinus, one of the paranasal sinuses.

Site of convertebral joint (cleft) of Luschka

The uncovertebral joint (joint of Luschka) is a specialized joint in the cervical spine.

Skin

In anatomy, the skin is the outer covering of the body, a complex organ that protects the internal structures, regulates temperature, and serves as a sensory interface with the environment.

Skin of scalp

The skin of the scalp is the outermost covering of the head, specialized for protection, sensation, and hair growth.

Skull

The skull is the bony structure of the head that supports the face and protects the brain. It is a complex anatomical structure made up of several bones, sutures, and foramina.

Slips of origin of anterior scalene muscle

The anterior scalene muscle is one of the scalene muscles of the neck, and its slips of origin refer to the specific points on the cervical vertebrae from which it arises.

Slips of origin of posterior scalene muscle

The posterior scalene muscle is another of the scalene muscles of the neck, lying posterolateral to the anterior and middle scalene muscles. Its slips of origin refer to the specific points on the cervical vertebrae from which it arises.

Small intestine

The small intestine is a long, tubular part of the gastrointestinal tract where most digestion and nutrient absorption occur.

Soft palate

The soft palate is the posterior, flexible part of the roof of the mouth, located behind the hard palate. It plays a key role in swallowing, speech, and separating the oral and nasal cavities.

Solitary tract nucleus

The solitary tract nucleus (also called the nucleus of the solitary tract or nucleus tractus solitarii, NTS) is a key sensory nucleus in the medulla oblongata that processes visceral sensory information.

Solitary tract nucleus (visceral afferents including taste)

The solitary tract nucleus (also called the nucleus of the solitary tract, NTS) is a major sensory nucleus in the medulla oblongata that processes visceral sensory information, including taste.

Sphenoethmoidal recess

The sphenoethmoidal recess is the space in the nasal cavity located superior to the superior nasal concha, into which the sphenoid sinus opens.

Sphenoid bone

The sphenoid bone is a centrally located, complex bone of the skull that forms a key part of the cranial base. Because of its shape, it is often described as bat-shaped or butterfly-shaped.

Sphenoid emissary foramen (of Vesalius)

The sphenoid emissary foramen (foramen of Vesalius) is a small, variable opening in the sphenoid bone that transmits an emissary vein connecting the cavernous sinus to the pterygoid venous plexus.

Sphenoid sinus

The sphenoid sinus is a pair of air-filled cavities within the body of the sphenoid bone, lined by respiratory mucosa, that drain into the sphenoethmoidal recess of the nasal cavity.

Sphenoidal concha

The sphenoidal concha is a small, paired bony plate of the sphenoid bone that forms the anterior and inferior walls of the sphenoid sinus and contributes to the roof of the nasal cavity, near the sphenoethmoidal recess.

Sphenoidal process of palatine bone

The sphenoidal process of the palatine bone is a small, upward-projecting bony process from the perpendicular plate of the palatine bone that articulates with the sphenoid bone. It helps form the boundaries of the pterygopalatine fossa and contributes to the lateral wall of the nasal cavity.

Sphenomandibular ligament

The sphenomandibular ligament is one of the three major ligaments of the temporomandibular joint (TMJ). It is a thin, flat, band-like ligament that extends from the sphenoid bone to the mandible and helps stabilize the mandible as it moves.

Sphenooccipital synchondrosis

The spheno-occipital synchondrosis is a cartilaginous joint between the sphenoid bone and the occipital bone at the base of the skull. It is one of the most important growth centers of the cranial base during childhood and adolescence.

Sphenopalatine artery

The sphenopalatine artery is the terminal branch of the maxillary artery that enters the nasal cavity through the sphenopalatine foramen and supplies most of the nasal septum and lateral nasal wall.

Sphenopalatine foramen

The sphenopalatine foramen is an opening in the superior part of the perpendicular plate of the palatine bone, bounded by the sphenoid and palatine bones, that allows passage of neurovascular structures from the pterygopalatine fossa into the nasal cavity.

Sphenopalatine vessels of incisive fossa

Sphenopalatine vessels of the incisive fossa are small terminal branches of the sphenopalatine artery and vein that reach the anterior hard palate by passing downward through the incisive canal from the nasal cavity.

Sphenoparietal sinus

The sphenoparietal sinus is a small dural venous sinus located along the undersurface of the lesser wing of the sphenoid bone, running near the junction of the sphenoid and parietal bones.

Spherical recess of vestibule

The spherical recess of the vestibule is a small, rounded depression on the medial wall of the vestibule of the inner ear that houses part of the saccule, one of the otolithic organs involved in balance.

Sphincter papillae muscle

The sphincter pupillae is a circular smooth muscle located in the iris of the eye that constricts the pupil.

Sphincter pupillae muscle

The sphincter pupillae is a ring-shaped smooth muscle located in the pupillary margin of the iris. Its contraction narrows the pupil (miosis) to regulate the amount of light entering the eye.

Spinal cord

The spinal cord is the long, cylindrical nervous tissue structure that extends from the brainstem downward through the vertebral canal and serves as the major pathway for transmitting information between the brain and the rest of the body.

Spinal nerve

A spinal nerve is one of 31 pairs of mixed nerves that form from the union of a dorsal (sensory) root and a ventral (motor) root of the spinal cord. After emerging from the spinal canal, each spinal nerve divides into branches that supply the skin, muscles, and organs.

Spinal nucleus of accessory nerve

The spinal nucleus of the accessory nerve is a long column of lower motor neurons located in the lateral portion of the anterior (ventral) horn of the cervical spinal cord, extending from approximately C1 to C5/C6. These neurons give rise to the spinal rootlets that form the spinal accessory nerve, which innervates the sternocleidomastoid and trapezius muscles.

Spinal nucleus of trigeminal nerve

The spinal trigeminal nucleus is a long sensory nucleus located in the lateral medulla, caudal pons, and upper cervical spinal cord. It receives pain, temperature, and crude touch afferents from the trigeminal nerve (CN V) and also from CN VII, IX, and X.

Spinal root of accessory nerve

The spinal root of the accessory nerve consists of motor rootlets that originate from the spinal nucleus of the accessory nerve in the ventrolateral horn of spinal cord segments C1–C5 (or C6). These rootlets emerge from the spinal cord, ascend into the skull through the foramen magnum, and then exit the skull through the jugular foramen as the spinal accessory nerve. This spinal root provides motor supply to the sternocleidomastoid and trapezius muscles.

Spinal roots of accessory nerve (XI) of jugular fossa

The spinal roots of the accessory nerve (cranial nerve XI) at the jugular fossa are the portion of the accessory nerve that arises from the cervical spinal cord, ascends into the skull, and then exits through the jugular foramen (specifically its jugular fossa portion) to supply motor fibers to the sternocleidomastoid and trapezius muscles.

Spinal roots of accessory nerves (XI) of foramen magnum

The spinal roots of the accessory nerve (cranial nerve XI) at the foramen magnum are the motor fibers originating from the cervical spinal cord that ascend into the cranial cavity through the foramen magnum before joining to form the accessory nerve proper.

Spinal segmental medullary branches

Spinal segmental medullary branches (also called segmental medullary arteries) are intermittent arterial branches that pass through the intervertebral foramina to join and reinforce the anterior spinal artery or the posterior spinal arteries. They do not occur at every spinal level, but where present, they are major contributors to spinal cord perfusion.

Spinal tract and spinal nucleus of trigeminal nerve

The spinal trigeminal tract and the spinal trigeminal nucleus form a major sensory pathway of the trigeminal nerve responsible for pain, temperature, and crude touch from the face. They extend from the pons → medulla → upper cervical spinal cord (C1–C3).

Spine of sphenoid bone

The spine of the sphenoid bone is a small, pointed, posterior projection on the inferior surface of the sphenoid bone, located at the posterolateral corner of the greater wing.

Spinous process

The spinous process is a posterior bony projection from a vertebra that serves as an important site for muscle attachment, ligament attachment, and protection of the spinal cord.

Spinous process of C7 (vertebra prominens)

The spinous process of C7, also known as the vertebra prominens, is the most prominent and easily palpable spinous process in the cervical spine. It serves as an important anatomical landmark at the base of the neck.

Spiral ganglion

The spiral ganglion is a collection of bipolar sensory neuron cell bodies located within the modiolus of the cochlea. These neurons transmit auditory information from the hair cells of the organ of Corti to the cochlear (auditory) nerve, a branch of cranial nerve VIII.

Spiral ligament

The spiral ligament is a thickened band of fibrous connective tissue located on the outer (lateral) wall of the cochlear duct, forming part of the osseous spiral lamina and supporting the basilar membrane along its lateral attachment.

Spiral organ (of Corti)

The spiral organ of Corti is a specialized sensory epithelium that rests on the basilar membrane inside the cochlea. It contains inner and outer hair cells, supporting cells, and associated structures necessary for detecting sound. It is the primary receptor organ for hearing.

Splenium of corpus callosum

The splenium is the posterior end of the corpus callosum. It contains heavily myelinated commissural fibers that interconnect the occipital lobes, parts of the temporal lobes, and the posterior parietal lobes across the midline. It is the thickest part of the corpus callosum.

Splenius muscle

The splenius muscle is a paired superficial muscle of the posterior neck that helps extend, rotate, and laterally flex the head and neck. It is divided into two parts: splenius capitis and splenius cervicis.

Spondylophytes (osteophytes) on uncinate process

Spondylophytes (osteophytes) on the uncinate process refer to bony outgrowths (bone spurs) that develop on the uncinate processes of cervical vertebrae, usually due to degenerative changes in the cervical spine.

Spread of cleft formation

The term “spread of cleft formation” usually refers to the progression or extension of a cleft in anatomical structures, commonly in the vertebral column (like the uncovertebral cleft of Luschka) or in facial/embryological clefts.

Squamous part of frontal bone

The squamous part of the frontal bone is the large, flat, vertical portion of the frontal bone that forms the forehead and the anterior wall of the cranial cavity.

Squamous part of temporal bone

The squamous part of the temporal bone is the flat, thin, fan-shaped portion of the temporal bone that forms the anterior and upper part of the temporal region of the skull.

Stapes

The stapes is the smallest bone in the human body and one of the three auditory ossicles in the middle ear. Its main role is to transmit sound vibrations from the middle ear to the inner ear.

Sternal head of sternocleidomastoid muscle

The sternal head of the sternocleidomastoid (SCM) muscle is one of the two heads of the sternocleidomastoid, a prominent neck muscle that plays a key role in head movement and neck anatomy.

Sternoclediomastoid muscle

The sternocleidomastoid (SCM) muscle is a prominent paired muscle in the lateral neck that is important for head movement, neck flexion, and respiration.

Sternocleidomastoid branch of occipital artery

The sternocleidomastoid branch of the occipital artery is a small branch that supplies the sternocleidomastoid muscle.

Sternocleidomastoid muscle

The sternocleidomastoid (SCM) muscle is a large, superficial neck muscle that is key for head movement, neck flexion, and accessory respiration.

Sternocleidomastoid nodes

The sternocleidomastoid nodes refer to lymph nodes located along or near the sternocleidomastoid (SCM) muscle in the neck. They are part of the cervical lymphatic system and are clinically important in evaluating head and neck infections or malignancies.

Sternocliedomastoid muscle

The sternocleidomastoid (SCM) muscle is a prominent, paired muscle in the lateral neck that plays a key role in head movement, neck flexion, and accessory respiration.

Sternohyoid muscle

The sternohyoid muscle is one of the infrahyoid (“strap”) muscles of the neck, mainly involved in depressing the hyoid bone.

Sternothyroid muscle

The sternothyroid muscle is one of the infrahyoid (“strap”) muscles of the neck, lying deep to the sternohyoid. Its main function is to depress the larynx during swallowing and speech.

Sternum

The sternum, also known as the breastbone, is a flat, elongated bone located in the anterior midline of the thorax. It plays a key role in protecting thoracic organs and serving as an attachment site for ribs and muscles.

Straight gyrus

The straight gyrus, also known as the gyrus rectus, is a part of the frontal lobe of the brain located on the inferior (orbital) surface of the frontal lobe.

Straight part of cricothyroid muscle

The straight part of the cricothyroid muscle is one of the two parts of the cricothyroid muscle, a muscle of the larynx that tenses the vocal cords to regulate pitch.

Straight sinus

The straight sinus is a dural venous sinus located in the brain, part of the venous system that drains blood from the brain toward the internal jugular veins.

Strap muscle

Strap muscles are a group of thin, long, flat muscles in the anterior neck that primarily stabilize or move the hyoid bone and larynx.

Stratified squamous epithelium

Stratified squamous epithelium is a type of epithelial tissue composed of multiple layers of cells, with the most superficial layer being flat (squamous) in shape. It is specialized to protect underlying tissues from mechanical stress, abrasion, and chemical damage.

Stria medullaris of thalamus

The stria medullaris (also called stria medullaris thalami) is a bundle of myelinated fibers located in the diencephalon of the brain. It serves as a key afferent pathway to the habenular nuclei.

Stria terminalis

The stria terminalis is a major fiber bundle in the brain that forms part of the limbic system, serving as the primary pathway connecting the amygdala to the hypothalamus.

Striae medullares

The term striae medullares generally refers to longitudinal fiber bundles in the brainstem or cerebellum, depending on context. Most commonly, it is associated with the fourth ventricle.

Striatum

The striatum is a major subcortical structure of the basal ganglia in the brain, playing a key role in motor control, reward, and cognitive functions.

Styloglossus muscle

The styloglossus muscle is one of the extrinsic muscles of the tongue, responsible for retracting and elevating the tongue.

Stylohyoid ligament

The stylohyoid ligament is a fibrous band connecting the temporal bone to the hyoid bone, playing an important role in suspending the hyoid and stabilizing the floor of the mouth.

Stylohyoid muscle

The stylohyoid muscle is one of the suprahyoid muscles of the neck, involved in elevating the hyoid bone during swallowing.

Styloid muscle

There isn’t a muscle strictly called the “styloid muscle” by itself. Usually, the term “styloid” refers to muscles that originate from the styloid process of the temporal bone.

Styloid process of temporal bone

The styloid process is a slender, pointed bony projection from the temporal bone of the skull, serving as an attachment point for muscles and ligaments of the neck, tongue, and pharynx.

Stylomandibular ligament

The stylomandibular ligament is a fibrous band connecting the styloid process of the temporal bone to the mandible, acting as a supportive structure for the jaw.

Stylomastoid foramen of temporal bone

The stylomastoid foramen is an important foramen in the temporal bone of the skull, serving as the exit point for the facial nerve (cranial nerve VII) from the skull.

Stylopharyngeus muscle

The stylopharyngeus muscle is a long, slender muscle of the pharynx that plays an important role in swallowing and elevating the pharynx and larynx.

Subarachnoid space

The subarachnoid space is a cerebrospinal fluid (CSF)-filled space in the central nervous system (CNS), located between the arachnoid mater and the pia mater. It plays a critical role in cushioning the brain and spinal cord and allowing circulation of CSF.

Subcallosal (parolfactory) area

The subcallosal area, also known as the parolfactory area, is a small region of the medial frontal lobe located just anterior to the genu of the corpus callosum. It is part of the limbic system and has connections with olfactory and limbic structures.

Subcallosal gyrus

The subcallosal gyrus is a small cortical region located on the medial surface of the frontal lobe, closely associated with the limbic system. It is sometimes considered part of the parolfactory (subcallosal) area.

Subclavian artery

The subclavian artery is a major artery of the upper thorax and neck that supplies blood to the upper limbs, neck, and brain.

Subclavian trunk and node

The subclavian trunk and subclavian lymph nodes are components of the lymphatic system in the neck and upper thorax, primarily responsible for draining lymph from the upper limb, breast, and superficial thoracic wall.

Subclavian vein

The subclavian vein is a major vein of the upper thorax and neck, responsible for draining venous blood from the upper limb, neck, and thoracic wall into the central venous system.

Subcutaneous tissue of scalp

Subcutaneous tissue, also called the hypodermis or superficial fascia, is the layer of connective tissue that lies beneath the skin (dermis) and above the deep fascia. It serves as a supportive, protective, and energy-storing layer.

Subependymal veins of brain

The subependymal veins are small veins located in the subependymal zone of the brain, primarily responsible for draining the deep structures of the cerebral hemispheres into larger venous systems.

Sublingual artery

The sublingual artery is a branch of the lingual artery that supplies the floor of the mouth and sublingual region.

Sublingual caruncle with opening of submandibular duct

The sublingual caruncle is a small, raised structure on the floor of the mouth, serving as the opening for the submandibular (Wharton’s) duct.

Sublingual fold with openings of sublingual ducts

The sublingual fold is a mucosal ridge on the floor of the mouth that contains the openings of the sublingual (Rivinus) ducts.

Sublingual fossa

The sublingual fossa is a depression on the internal surface of the mandible that houses the sublingual gland.

Sublingual gland

The sublingual gland is one of the major salivary glands, located in the floor of the mouth. It is the smallest of the major salivary glands and mainly produces mucous saliva.

Sublingual nerve

The sublingual nerve is a branch of the lingual nerve (itself a branch of the mandibular division of the trigeminal nerve, CN V3) that supplies sensation and contributes to parasympathetic innervation in the floor of the mouth.

Sublingual vein

The sublingual vein is a superficial vein in the floor of the mouth that primarily drains blood from the tongue and sublingual region into the lingual and facial venous systems.

Sublingual salivary gland

The sublingual salivary gland is one of the three major pairs of salivary glands in the human body, located in the floor of the mouth beneath the tongue.

Submandibular duct

The submandibular duct, also known as Wharton’s duct, is the excretory duct of the submandibular salivary gland.

Submandibular fossa

The submandibular fossa is a depression on the internal (medial) surface of the mandible that accommodates the submandibular salivary gland.

Submandibular ganglion

The submandibular ganglion is a small parasympathetic ganglion associated with the facial nerve (CN VII) that controls salivary secretion in the submandibular and sublingual glands.

Submandibular gland

The submandibular gland is one of the major salivary glands, responsible for producing both serous and mucous saliva.

Submandibular lymph node

The submandibular lymph nodes are an important group of cervical lymph nodes located in the submandibular region of the neck.

Submandibular nodes

The submandibular nodes are a group of cervical lymph nodes located in the submandibular (digastric) triangle of the neck, closely associated with the submandibular salivary gland.

Submental artery

The submental artery is a branch of the facial artery that supplies the floor of the mouth and adjacent structures.

Submental node

The submental lymph nodes are a small group of cervical lymph nodes located in the submental triangle of the neck, just beneath the chin.

Submental nodes

The submental lymph nodes are a small group of cervical lymph nodes located in the submental triangle of the neck, just beneath the chin.

Submental vein

The submental vein is a superficial vein in the floor of the mouth and chin region that drains venous blood from the submental area into larger veins of the neck.

Suboccipital nerve (dorsal ramus of C1 spinal nerve)

The suboccipital nerve is the dorsal ramus of the first cervical spinal nerve (C1) and is primarily a motor nerve that innervates muscles in the suboccipital region.

Subparotid node

The subparotid lymph nodes are a group of cervical lymph nodes located near or within the parotid region of the face and neck.

Subscapular artery

The subscapular artery is the largest branch of the axillary artery, supplying the posterior shoulder region.

Substantia nigra

The substantia nigra is a key structure in the midbrain (mesencephalon) that plays a crucial role in movement control and reward pathways.

Sulcus limitans

The sulcus limitans is an important anatomical landmark in the developing and adult brainstem, particularly within the floor of the fourth ventricle.

Sulcus of corpus callosum

The sulcus of the corpus callosum is a groove that runs along the superior or dorsal surface of the corpus callosum, separating it from the cingulate gyrus above.

Superciliary arch

The superciliary arch is a bony ridge located on the frontal bone, just above the orbit.

Superficial (investing) layer of deep cervical fascia

The superficial (investing) layer of deep cervical fascia is the outermost layer of deep fascia in the neck, which encloses the entire neck and provides structural support and compartmentalization.

Superficial arteries

Superficial arteries are blood vessels that run close to the surface of the body, just beneath the skin, supplying skin, subcutaneous tissue, muscles, and sometimes underlying structures. They are often palpable and important in clinical, surgical, and anatomical contexts.

Superficial branch of transverse cervical artery (superficial cervical artery)

The superficial branch of the transverse cervical artery, also called the superficial cervical artery, is an important vessel in the posterior and lateral neck region.

Superficial cervical artery

The superficial cervical artery, also known as the superficial branch of the transverse cervical artery, is a blood vessel in the posterior neck that supplies the trapezius muscle and overlying skin.

Superficial layer of deep cervical fascia

The superficial layer of deep cervical fascia, also called the investing layer of deep cervical fascia, is the outermost layer of deep fascia in the neck, enclosing the neck like a collar. It provides structural support, protection, and compartmentalization.

Superficial layer of temporal fascia

The superficial layer of temporal fascia is an important fascial structure of the temporal region of the head, covering the temporalis muscle and forming part of the temporal compartment.

Superficial middle cerebral vein

The superficial middle cerebral vein (SMCV) is a major cerebral vein that drains the lateral surface of the cerebral hemisphere, particularly the lateral (Sylvian) fissure.

Superficial parotid nodes (deep parotid nodes to and within parotid gland)

The superficial parotid lymph nodes are part of the parotid lymphatic system, which drains regions of the face, scalp, and external ear. They are closely associated with the parotid gland and are clinically important in infections and tumors.

Superficial part of masseter muscle

The superficial part of the masseter muscle is the largest and most prominent portion of the masseter, one of the main muscles of mastication.

Superficial temporal artery

The superficial temporal artery is a major artery of the scalp and one of the terminal branches of the external carotid artery.

Superficial temporal branches of mandibular nerve

The superficial temporal branches of the mandibular nerve are sensory branches of the auriculotemporal nerve, itself a branch of V₃ (mandibular nerve). They supply the temporal region and surrounding structures.

Superficial temporal vein

The superficial temporal vein is a major venous drainage vessel of the lateral scalp and temporal region, running alongside the superficial temporal artery.

Superficial veins

Superficial veins are veins located close to the surface of the body, typically in the subcutaneous tissue, that drain blood from the skin, subcutaneous tissue, and superficial muscles into deeper veins or directly into larger superficial veins.

Superior nasal retinal arteriole and venule

The superior nasal retinal arteriole and venule are small blood vessels in the retina that specifically supply and drain the superior nasal quadrant of the retina in the eye. They are part of the central retinal circulation, which is essential for the retina’s function and visual processing.

Superior oblique muscle

The superior oblique muscle is one of the extraocular muscles of the eye, responsible for specific movements of the eyeball.

Superior alveolar arteries

The superior alveolar arteries are branches of the maxillary artery that supply the maxillary teeth, maxillary sinus, and adjacent structures. They are divided into posterior, middle, and anterior superior alveolar arteries.

Superior alveolar branches of infraorbital nerve of maxillary nerve

The superior alveolar branches of the infraorbital nerve are sensory nerves that supply the maxillary teeth, adjacent gingiva, and maxillary sinus. They are branches of the maxillary nerve (V₂) via the infraorbital nerve.

Superior alveolar nerves

The superior alveolar nerves are sensory nerves that supply the maxillary (upper) teeth, adjacent gingiva, and parts of the maxillary sinus. They are branches of the maxillary nerve (V₂), a division of the trigeminal nerve (cranial nerve V).

Superior anastomotic vein (of Trolard)

The superior anastomotic vein, also known as the vein of Trolard, is an important superficial cerebral vein connecting the superficial venous system of the brain.

Superior and inferior palpebral arterial arches

The superior and inferior palpebral arterial arches are arterial arcades located within the upper and lower eyelids, forming the main blood supply to the eyelid tissues.

Superior and inferior salivatory nuclei

The superior and inferior salivatory nuclei are parasympathetic nuclei in the brainstem that control salivary gland secretion and some glands of the head. They are part of the visceral motor system and send preganglionic parasympathetic fibers through cranial nerves VII and IX.

Superior and inferior transverse scapular ligaments

The superior and inferior transverse scapular ligaments are small but important ligamentous structures associated with the scapular notch region and spinoglenoid notch of the scapula. They play key roles in forming osteoligamentous foramina for nerves and vessels in the shoulder.

Superior articular process

The superior articular process is a paired bony projection found on vertebrae that participates in forming the joints between adjacent vertebrae.

Superior articular facet

The superior articular facet is the smooth, cartilage-covered articular surface that sits on top of the superior articular process of a vertebra. It forms part of the zygapophysial (facet) joints between adjacent vertebrae and helps determine the type and range of spinal motion possible in each region.

Superior articular facet for atlas

The superior articular facet for the atlas refers to the special superior articular facets of the axis (C2) that articulate with the inferior articular facets of the atlas (C1). These facets form the lateral atlanto-axial joints, which allow most of the rotation of the head (“no” motion).

Superior articular process

The superior articular process is a paired bony projection on each vertebra that participates in forming the facet (zygapophysial) joints with the vertebra above. These joints guide and limit spinal movement and contribute to the stability of the vertebral column.

Superior articular process (C4)

The superior articular process of C4 is one of the paired upward-projecting processes on the fourth cervical vertebra, forming the facet joint with the inferior articular process of C3.

Superior articular surface for occipital condyle

The superior articular surfaces of the atlas (C1) are the smooth, concave, kidney-shaped facets located on the lateral masses of the atlas. These facets articulate directly with the occipital condyles of the skull to form the atlanto-occipital joint.

Superior aspect of C4

The superior aspect of C4 refers to the top view of the fourth cervical vertebra, showing the structures visible when looking down onto its superior surface. This includes the vertebral body, articular facets, transverse processes, pedicles, and laminae.

Superior belly

The term “superior belly” usually refers to the superior belly of the omohyoid muscle, though there are a few “superior bellies” in anatomy (like digastric).

Superior branch of oculomotor nerve (III)

The superior branch of the oculomotor nerve (CN III) is one of the two divisions of the oculomotor nerve after it passes through the superior orbital fissure, responsible for motor innervation of certain extraocular muscles.

Superior bulb of right internal jugular vein

The superior bulb of the internal jugular vein is an important venous structure at the proximal part of the internal jugular vein (IJV) near its origin at the jugular foramen.

Superior cerebellar artery

The superior cerebellar artery (SCA) is an important branch of the basilar artery that supplies parts of the cerebellum, midbrain, and brainstem.

Superior cerebellar peduncle

The superior cerebellar peduncle (SCP) is one of the three paired cerebellar peduncles connecting the cerebellum to the brainstem. It is primarily an efferent (output) pathway, but also carries some afferent fibers.

Superior cerebellar vein

The superior cerebellar vein (SCV) is one of the veins that drain the superior surface of the cerebellum and empty into the veins of the posterior cranial fossa, contributing to the venous drainage of the cerebellum.

Superior cerebellary artery

The superior cerebellar artery (SCA) is one of the main arteries supplying the cerebellum and nearby structures.

Superior cervical cardiac branch of vagus nerve

The superior cervical cardiac branch of the vagus nerve is a small autonomic branch that contributes to the cardiac plexus, carrying parasympathetic fibers from the vagus nerve to the heart.

Superior cervical cardiac nerve

The superior cervical cardiac nerve (sometimes called the superior cervical cardiac branch) is a small autonomic nerve arising from the superior cervical region of the sympathetic or vagus system, contributing fibers to the cardiac plexus.

Superior cervical ganglion

The superior cervical ganglion (SCG) is the largest and most rostral ganglion of the sympathetic chain, located in the neck. It provides sympathetic innervation to the head, neck, and heart.

Superior cervical sympathetic cardiac nerve

The superior cervical sympathetic cardiac nerve is a small autonomic branch arising from the superior cervical ganglion (SCG) of the sympathetic chain, contributing sympathetic fibers to the cardiac plexus.

Superior cervical sympathetic ganglion

The superior cervical sympathetic ganglion (SCG) is the largest and most rostral ganglion of the sympathetic chain, located in the neck. It is a key autonomic structure supplying sympathetic innervation to the head, neck, and heart.

Superior choroid vein

The superior choroid vein is a vein of the lateral ventricle in the brain that primarily drains the choroid plexus and adjacent ventricular structures.

Superior colliculi

The superior colliculi are paired structures on the dorsal aspect of the midbrain that are part of the tectum and play a key role in visual processing and reflexes.

Superior conjunctival fornix

The superior conjunctival fornix is the upper fold of the conjunctiva in the eye where the inner surface of the upper eyelid (palpebral conjunctiva) reflects onto the eyeball (bulbar conjunctiva).

Superior deep lateral cervical (internal jugular) nodes

The superior deep lateral cervical nodes (also called superior internal jugular nodes) are part of the deep cervical lymph node group, located along the internal jugular vein in the neck.

Superior dental plexus

The superior dental plexus is a network of nerves that supplies sensation to the upper teeth, gums, and adjacent structures.

Superior division of oculomotor nerve

The superior division of the oculomotor nerve (CN III) is one of the two main branches of the oculomotor nerve, responsible for innervating specific extraocular muscles that control eye movements.

Superior division of vestibular nerve

The superior division of the vestibular nerve is a branch of the vestibular portion of the vestibulocochlear nerve (CN VIII) that transmits sensory information about balance and head position from the inner ear to the brain.

Superior fovea

The superior fovea refers to a part of the retina in the eye, specifically the foveal region, which is responsible for high-acuity vision.

Superior frontal gyrus

The superior frontal gyrus (SFG) is a prominent structure in the frontal lobe of the brain.

Superior frontal sulcus

The superior frontal sulcus (SFS) is a groove on the lateral surface of the frontal lobe that separates two major gyri.

Superior ganglia of glossopharyngeal nerve

The superior ganglion of the glossopharyngeal nerve (cranial nerve IX) is one of the two sensory ganglia associated with this nerve.

Superior ganglion of vagus nerve

The superior ganglion of the vagus nerve (cranial nerve X) is one of the two sensory ganglia associated with this nerve.

Superior horn of thyroid cartilage

The superior horn of the thyroid cartilage is a structural feature of the thyroid cartilage, which is the largest cartilage of the larynx.

Superior hypophyseal artery

The superior hypophyseal artery (SHA) is an important branch of the internal carotid artery that supplies the pituitary gland.

Superior labial artery

The superior labial artery is a branch of the facial artery that supplies the upper lip and surrounding structures.

Superior labial vein

The superior labial vein is the venous counterpart of the superior labial artery and is responsible for draining blood from the upper lip.

Superior lacrimal papilla and punctum

The superior lacrimal papilla and superior lacrimal punctum are small but essential structures of the lacrimal drainage system of the eye.

Superior laryngeal nerve

The superior laryngeal nerve (SLN) is a branch of the vagus nerve (cranial nerve X) that plays an essential role in laryngeal sensation and motor control.

Superior laryngeal vein

The superior laryngeal vein is a venous vessel associated with the larynx that drains blood from the upper part of the larynx.

Superior lateral nasal nerves

The superior lateral nasal nerves are sensory branches of the ophthalmic division (V₁) of the trigeminal nerve that supply the lateral aspect of the nose.

Superior lateral palpebral artery

The superior lateral palpebral artery is a small artery that contributes to the vascular supply of the upper eyelid.

Superior lateral superficial cervical (external jugular) node

The superior lateral superficial cervical node is a superficial lymph node located along the external jugular vein in the lateral neck.

Superior ligament of incus

The superior ligament of the incus is a small ligament in the middle ear that helps stabilize the ossicular chain.

Superior ligament of malleus

The superior ligament of the malleus is a small ligament in the middle ear that helps stabilize the malleus, one of the auditory ossicles.

Superior longitudinal band of cruciate ligament

The superior longitudinal band of the cruciate ligament is part of the cruciate ligament of the atlas (C1) in the cervical spine.

Superior longitudinal muscle of tongue

The superior longitudinal muscle of the tongue is one of the intrinsic muscles of the tongue, responsible for changing the shape of the tongue rather than moving it in space.

Superior longitudinal of intrinsic muscles of tongue

The superior longitudinal muscle is one of the intrinsic muscles of the tongue, and is specifically part of the intrinsic longitudinal group.

Superior macular arteriole and venule

The superior macular arteriole and venule are the small blood vessels supplying and draining the superior portion of the macula in the retina.

Superior medial palpebral artery

The superior medial palpebral artery is a small artery supplying the medial part of the upper eyelid.

Superior medullary velum

The superior medullary velum is a thin sheet of white matter in the brain that forms part of the roof of the fourth ventricle.

Superior mental spine (genial tubercle) for origin of genioglossus muscle

The superior mental spine, also known as the genial tubercle, is an anatomical landmark on the mandible that serves as the origin of the genioglossus muscle.

Superior mesenteric ganglia

The superior mesenteric ganglia are part of the prevertebral sympathetic ganglia associated with the autonomic nervous system, specifically the sympathetic division.

Superior nasal concha of ethmoid bone

The superior nasal concha of the ethmoid bone is a thin, curved bony structure in the lateral wall of the nasal cavity, forming part of the ethmoid bone.

Superior nasal meatus

The superior nasal meatus is a passage in the lateral wall of the nasal cavity located below the superior nasal concha.

Superior nasal meatus with opening of posterior ethmoidal cells

The superior nasal meatus with the openings of the posterior ethmoidal cells is an anatomical region in the lateral wall of the nasal cavity that serves as a drainage pathway for the posterior ethmoid sinuses.

Superior nuchal line of occipital bone

The superior nuchal line is an important bony ridge on the occipital bone of the skull that serves as an attachment site for muscles and ligaments of the neck.

Superior oblique muscle

The superior oblique muscle is one of the extraocular muscles responsible for eye movement.

Superior oblique muscle of trochlear nerve (IV)

The superior oblique muscle is an extraocular muscle uniquely innervated by the trochlear nerve (cranial nerve IV).

Superior ophthalmic vein

The superior ophthalmic vein (SOV) is a major venous drainage vessel of the orbit that connects the facial venous system to the cavernous sinus.

Superior ophthalmic vein of superior orbital fissure

The superior ophthalmic vein (SOV) is the main venous channel of the orbit that passes through the superior orbital fissure to drain into the cavernous sinus.

Superior orbital fissure

The superior orbital fissure (SOF) is a key opening in the posterior orbit that allows passage of nerves and vessels between the cranial cavity and the orbit.

Superior palpebral conjunctiva

The superior palpebral conjunctiva is the mucous membrane lining the inner surface of the upper eyelid.

Superior parathyroid gland

The superior parathyroid glands are small endocrine glands located in the neck that play a crucial role in calcium homeostasis.

Superior parietal lobule

The superior parietal lobule (SPL) is a prominent region of the parietal lobe in the brain, involved in sensory integration, spatial orientation, and visuomotor coordination.

Superior part of vestibular nerve

The superior part of the vestibular nerve is a division of the vestibular portion of the vestibulocochlear nerve (cranial nerve VIII) that carries balance information from the inner ear to the brain.

Superior petrosal sinus

The superior petrosal sinus is a dural venous sinus located at the base of the skull that forms part of the cerebral venous drainage system, connecting the cavernous sinus to the transverse sinus.

Superior pharyngeal constrictor muscle

The superior pharyngeal constrictor muscle is one of the three paired pharyngeal constrictor muscles that form the posterolateral wall of the pharynx, playing a critical role in swallowing.

Superior rectus muscle of oculomotor nerve (III)

The superior rectus muscle is an extraocular muscle specifically innervated by the superior division of the oculomotor nerve (cranial nerve III).

Superior retrotonsillar vein

The superior retrotonsillar vein is a small venous structure in the pharyngeal region that contributes to the venous drainage of the tonsillar and oropharyngeal area.

Superior root of ansa cervicalis

The superior root of the ansa cervicalis is a key component of the cervical nerve loop that innervates most of the infrahyoid (“strap”) muscles in the neck.

Superior sagittal sinus

The superior sagittal sinus (SSS) is the largest dural venous sinus in the human brain and a key structure in cerebral venous drainage.

Superior salivatory nucleus

The superior salivatory nucleus (SSN) is a parasympathetic motor nucleus in the brainstem responsible for innervating glands of the head.

Superior salivatory nucleus (parasympathetic)

The superior salivatory nucleus (SSN) is a parasympathetic motor nucleus in the brainstem that controls secretomotor activity of several head glands.

Superior semilunar (anseriform) lobule of posterior lobe of cerebellum

The superior semilunar (anseriform) lobule is a subdivision of the posterior lobe of the cerebellum, involved primarily in coordination of limb movements.

Superior surface of orbital part of frontal bone

The superior surface of the orbital part of the frontal bone is the roof of the orbit, forming part of the anterior cranial fossa.

Superior tarsal (Muller's) muscle (smooth)

The superior tarsal muscle, also known as Müller’s muscle, is a smooth (involuntary) muscle of the eyelid that assists in upper eyelid elevation.

Superior tarsus

The superior tarsus (also called the superior tarsal plate) is a dense, fibrous structure in the upper eyelid that provides shape, support, and attachment for eyelid muscles.

Superior temporal gyrus

The superior temporal gyrus (STG) is a prominent structure of the temporal lobe of the brain, involved in auditory processing, language comprehension, and social cognition.

Superior temporal line

The superior temporal line is a bony ridge on the lateral aspect of the skull that serves as an important muscle attachment site.

Superior temporal retinal arteriole and venule

The superior temporal retinal arteriole and venule are part of the retinal circulation, supplying and draining the superior temporal quadrant of the retina.

Superior temporal sulcus

The superior temporal sulcus (STS) is a major groove on the lateral surface of the temporal lobe that separates the superior temporal gyrus (STG) from the middle temporal gyrus (MTG). It is involved in social perception, language, and multimodal sensory integration.

Superior terminal branches

The term “superior terminal branches” generally refers to the final, distal branches of a larger vessel or nerve that are located superiorly, meaning toward the upper aspect of the structure or region. It’s not a single anatomical structure; rather, it’s a descriptive term used in anatomy.

Superior thalamic veins

The superior thalamic veins are part of the venous drainage system of the thalamus, carrying blood from the thalamic nuclei to the internal cerebral veins and eventually to the great cerebral vein (vein of Galen).

Superior thalamostriate and choroidal veins

The superior thalamostriate vein and superior choroidal vein are important deep cerebral veins that drain blood from the thalamus, striatum, and choroid plexus into the internal cerebral veins.

Superior thalamostriate vein

The superior thalamostriate vein is a deep cerebral vein that plays a critical role in draining the thalamus and striatum into the internal cerebral vein.

Superior thyroid artery

The superior thyroid artery (STA) is the first and typically the largest branch of the external carotid artery, supplying the thyroid gland and adjacent structures.

Superior thyroid nodes

Superior thyroid nodes (often called superior deep cervical lymph nodes at the level of the thyroid or simply upper deep cervical nodes) are lymph nodes located along the upper portion of the internal jugular vein, near the level of the thyroid gland, usually just above or around the superior thyroid artery.

Superior thyroid notch

The superior thyroid notch is a prominent V-shaped indentation on the upper border of the thyroid cartilage of the larynx.

Superior thyroid vein

The superior thyroid vein is a major vein that drains the upper portion of the thyroid gland and nearby structures in the anterior neck.

Superior vena cava

The superior vena cava (SVC) is a large, short vein in the upper chest that returns deoxygenated blood from the upper half of the body to the right atrium of the heart.

Superior vermian branch

The superior vermian branch refers to small arterial or venous branches supplying or draining the superior vermis—the midline portion of the cerebellum on its superior (dorsal) surface.

Superior vermian vein

The superior vermian vein is a midline cerebellar vein that drains the superior vermis (the central midline portion on the superior surface of the cerebellum).

Superior vermis

The superior vermis is the midline portion of the cerebellum located on its superior (dorsal) surface. It forms the central region between the two cerebellar hemispheres and plays a key role in posture, balance, and coordination of trunk movements.

Superior vestibular nuclei

The superior vestibular nucleus (also called the Bechterew nucleus) is one of the four major vestibular nuclei located in the dorsolateral pons. It is part of the central vestibular system that processes balance, head-position, and eye-movement signals.

Superior ophthalmic vein

The superior ophthalmic vein (SOV) is the main venous drainage vessel of the orbit. It carries blood from the eye and orbit into the cavernous sinus inside the skull.

Superior sagittal sinus

The superior sagittal sinus (SSS) is a large dural venous sinus that runs along the midline of the skull, between the layers of the dura mater, and drains venous blood from the cerebral hemispheres into the confluence of sinuses.

Supra-optic recess

The supra-optic recess is a small cavity or indentation in the floor of the third ventricle of the brain, located just above the optic chiasm. It is part of the ventricular system and is closely related to the hypothalamus.

Supraclavicular nerves

The supraclavicular nerves are cutaneous (sensory) branches of the cervical plexus that provide sensation to the skin over the shoulder and upper chest.

Supraclavicular nodes

The supraclavicular lymph nodes are a group of deep cervical lymph nodes located just above the clavicle, at the junction of the neck and thorax. They are important clinically because they can indicate distant or regional malignancy.

Suprahyoid artery

The suprahyoid artery is a small muscular branch of the lingual artery (occasionally from the facial artery). It runs above the hyoid bone and supplies the structures in that region.

Suprahyoid node

A suprahyoid lymph node refers to any lymph node situated superior to the hyoid bone, typically in the region between the mandible and the hyoid. These nodes lie in the suprahyoid (floor-of-mouth) anatomical compartment.

Supramarginal gyrus of inferior parietal lobule

The supramarginal gyrus (SMG) is a major convolution of the inferior parietal lobule (IPL) in the parietal lobe of the brain. It wraps around the posterior end of the lateral sulcus (Sylvian fissure).

Supraoptic hypothalamic nucleus

The supraoptic nucleus (SON) is one of the major hypothalamic nuclei involved in neuroendocrine control, especially the regulation of body water balance.

Supraoptic nuclei of hypothalamus

The supraoptic nuclei of the hypothalamus (SONs) are a pair of major magnocellular neurosecretory nuclei located in the anterior hypothalamus. They are among the most important structures for water balance, osmoregulation, and neuroendocrine hormone release.

Supraoptic recess

The supraoptic recess is a small upward extension of the third ventricle located in the anterior part of the hypothalamus, immediately above the optic chiasm.

It is one of the small diverticula (recesses) of the third ventricle.

Supraopticohypophyseal tract

The supraopticohypophyseal tract is the bundle of axons that carries hormones from the supraoptic nucleus (and partly the paraventricular nucleus) of the hypothalamus down to the posterior pituitary (neurohypophysis).

It is a major component of the hypothalamo-neurohypophyseal system.

Supraorbital artery

The supraorbital artery is a major branch of the ophthalmic artery that supplies the forehead, scalp, upper eyelid, and frontal sinus region. It travels with the supraorbital nerve.

Supraorbital nerve

The supraorbital nerve is a major sensory branch of the ophthalmic division (V1) of the trigeminal nerve. It provides cutaneous sensation to the forehead, scalp, and upper eyelid.

Supraorbital nerve branches

The supraorbital nerve, a terminal branch of the frontal nerve (CN V1), divides into two main branches after exiting the supraorbital notch/foramen. These branches provide sensory innervation to the forehead, scalp, and frontal sinus.

Supraorbital notch

The supraorbital notch is an important anatomical landmark on the frontal bone that serves as a passage for the supraorbital nerve, artery, and vein from the orbit to the forehead.

Supraorbital notch (foramen)

The supraorbital notch (or foramen) is a key anatomical structure on the frontal bone that acts as a passageway for neurovascular structures supplying the forehead, anterior scalp, and upper eyelid. It is often referred to as a notch when it is open and groove-like, and as a foramen when completely enclosed by bone.

Supraorbital vein

The supraorbital vein is a vein that drains blood from the forehead and anterior scalp and communicates with the ophthalmic veins, forming an important venous connection between the face and the cavernous sinus.

Suprapineal recess

The suprapineal recess is a small anatomical extension of the third ventricle located above the pineal gland. It is one of several ventricular recesses that serve as landmarks in neuroanatomy.

Suprascapular artery

The suprascapular artery is an important branch of the subclavian or thyrocervical system that supplies blood to the posterior shoulder region, including the supraspinatus and infraspinatus muscles.

Suprascapular vein

The suprascapular vein is the venous counterpart of the suprascapular artery. It drains the posterior scapular region, including the supraspinatus and infraspinatus muscles, and communicates with the external jugular vein system.

Suprasternal space (of Burns)

The suprasternal space (of Burns) is a small anatomical fascial space in the lower part of the neck, also known as the episternal space. It is clinically significant because it provides a potential space for infection spread and is an important landmark in neck surgery.

Supratonsillar fossa

The supratonsillar fossa is an anatomical space located just above the palatine tonsil in the oropharynx. It is clinically relevant in tonsil surgery and for understanding peritonsillar abscess formation.

Supratrochlear artery

The supratrochlear artery is a branch of the ophthalmic artery that supplies the medial forehead and upper eyelid region. It is closely associated with the supratrochlear nerve.

Supratrochlear nerve

The supratrochlear nerve is a small sensory branch of the ophthalmic division (V₁) of the trigeminal nerve (cranial nerve V).

Supratrochlear vein

The supratrochlear vein is a superficial vein of the forehead that contributes to the venous drainage of the upper face.

Supreme (superior) intercostal artery

The supreme (superior) intercostal artery is a branch of the costocervical trunk, which itself arises from the subclavian artery.

Sustentacular cell

Sustentacular cells are supporting cells found in different tissues, but the term is most commonly used in two major contexts: the olfactory epithelium and the testis (though in the testis, “Sertoli cells” is the preferred name).

Suture (wormian) bone

A suture (Wormian) bone is a small, irregular extra bone that forms within a cranial suture of the skull.

Styloid process

The styloid process is a slender, pointed, bony projection that extends downward and forward from the temporal bone of the skull.

Sympathetic fibers

Sympathetic fibers are the nerve fibers of the sympathetic division of the autonomic nervous system (ANS). They control involuntary responses associated with “fight-or-flight” functions.

Sympathetic postganglionic fibers

Sympathetic postganglionic fibers are the axon fibers that originate from sympathetic ganglion cells and travel to their target organs after the synapse between preganglionic and ganglionic neurons.

Sympathetic preganglionic fibers

Sympathetic preganglionic fibers are the myelinated nerve fibers that originate in the spinal cord and synapse in sympathetic ganglia before reaching their final targets.

Sympathetic root of ciliary ganglion

The sympathetic root of the ciliary ganglion is the sympathetic pathway entering the ciliary ganglion, but it does NOT synapse there. The ciliary ganglion is a parasympathetic ganglion, and sympathetic fibers simply pass through.

Sympathetic trunk

The sympathetic trunk (also called the sympathetic chain) is a paired bundle of nerve fibers that runs along the length of the vertebral column and is a major part of the sympathetic division of the autonomic nervous system (ANS).

Synovial cavities

Synovial cavities are a fundamental feature of synovial joints, which are the most mobile type of joint in the human body.

The T1 vertebra is the first thoracic vertebra, located at the junction between the cervical and thoracic spine, and serves as a transition vertebra with features of both cervical and thoracic vertebrae.

T1 spinal nerve

The T1 spinal nerve is the first thoracic spinal nerve, emerging from the spinal cord at the level of the T1 vertebra. It plays a crucial role in the brachial plexus and provides both motor and sensory innervation.

The T2 vertebra is the second thoracic vertebra of the spine. It is part of the thoracic segment, which is characterized by its articulation with ribs and features that provide stability to the thoracic cage.

T2 spinal nerve

The T2 spinal nerve is the second thoracic spinal nerve, emerging from the spinal cord at the level of the T2 vertebra. It is part of the thoracic segment of the spinal nerves and mainly contributes to intercostal nerve supply and the upper thoracic wall.

Taenia of 4th ventricle

The taenia of the fourth ventricle are thin bands of white matter associated with the floor of the fourth ventricle in the brain.

Tail of caudate nucleus

The tail of the caudate nucleus is the posterior portion of the caudate nucleus, one of the key structures of the basal ganglia in the brain.

Tarsal (meibomian) glands

The tarsal glands, also called Meibomian glands, are specialized sebaceous glands located within the tarsal plates of the eyelids. They are crucial for eye lubrication and tear film stability.

Tarsus of eyelid

The tarsus of the eyelid (plural: tarsi) is a dense, fibrous plate that provides structural support to the eyelid and serves as a site of attachment for muscles and glands.

Taste buds

Taste buds are specialized sensory organs responsible for detecting taste (gustation). They are found primarily on the tongue, but also in other parts of the oral cavity and pharynx.

Taste pore

The taste pore is a small opening at the surface of the epithelium of the tongue that allows the microvilli (taste hairs) of gustatory cells to come into contact with substances in saliva.

Tectal (quadrigeminal) plate

The tectal plate, also known as the quadrigeminal plate, is a key structure in the midbrain (mesencephalon) involved in visual and auditory reflexes.

Tectorial membrane

The tectorial membrane is a specialized extracellular structure in the inner ear that plays a critical role in hearing by interacting with the organ of Corti.

Tectospinal tract

The tectospinal tract is a descending motor pathway that originates in the midbrain and is involved in reflexive head and neck movements in response to visual and auditory stimuli.

Teeth

Teeth are hard, calcified structures in the oral cavity that are essential for mastication (chewing), speech, and appearance. They are part of the dentition and are classified by type, structure, and development.

Tegmen tympani

The tegmen tympani is a thin bony plate in the temporal bone that forms part of the roof of the tympanic cavity (middle ear). It plays an important role in separating the middle ear from the cranial cavity.

Tela choroidea of 3rd ventricle

The tela choroidea of the third ventricle is a thin, vascular membrane that forms part of the choroid plexus of the third ventricle, which produces cerebrospinal fluid (CSF).

Temporal (inferior) horn of lateral ventricle

The temporal (inferior) horn of the lateral ventricle is a part of the lateral ventricle that extends into the temporal lobe of the brain. It is important in cerebrospinal fluid (CSF) circulation and is closely related to several key structures.

Temporal bone

The temporal bone is a complex, paired bone of the lateral skull that houses important structures related to hearing, balance, and neurovascular passage. It contributes to the cranial base, side of the skull, and part of the cranial cavity.

Temporal branches

The temporal branches usually refer to the temporal branches of the facial nerve (cranial nerve VII), which supply muscles of facial expression in the forehead and temple region.

Temporal branches of anterior cerebral artery

The anterior cerebral artery (ACA) primarily supplies the medial portions of the frontal and parietal lobes, but it also gives off temporal branches in certain regions of the temporal lobe. These branches are much smaller and less prominent than those of the middle or posterior cerebral arteries.

Temporal branches of middle cerebral artery

The temporal branches of the middle cerebral artery (MCA) are the cortical arteries that supply the temporal lobe. They arise mainly from the M2 segment (insular segment) of the MCA and run along the lateral (Sylvian) fissure toward the temporal cortex.

Temporal branches of posterior cerebral artery

The temporal branches of the posterior cerebral artery (PCA) are cortical arteries that supply parts of the temporal lobe and hippocampal region. They arise from the P2 segment of the PCA (the part that runs around the midbrain in the ambient cistern) and course laterally and inferiorly toward the temporal lobe.

Temporal fascia

The temporal fascia is a strong, fibrous sheet that covers the temporal muscle (temporalis) on the side of the skull. It helps contain and support the muscle and provides attachment for surrounding structures.

Temporal fossa

The temporal fossa is a shallow depression on the lateral aspect of the skull that houses the temporalis muscle.

Temporal horn of lateral ventricle

The temporal horn (also called the inferior horn) is the anteroinferior extension of the lateral ventricle that projects into the temporal lobe. It is C-shaped, following the curvature of the lateral ventricle.

Temporal lobe

The temporal lobe is one of the four major lobes of the cerebral cortex and is located on the lateral and inferior aspect of the brain, beneath the lateral sulcus (Sylvian fissure). It plays key roles in auditory processing, memory, language, and emotion.

Temporal operculum

The temporal operculum is a specific anatomical region of the temporal lobe that forms part of the lateral surface covering the insula. It’s an important structure in language, auditory processing, and cortical mapping.

Temporal pole of cerebrum

The temporal pole of the cerebrum is the anteromedial tip of the temporal lobe, representing the most anterior portion of the cerebral hemisphere’s temporal lobe. It is an important anatomical and functional region due to its connections with the limbic system and its role in memory, language, and social-emotional processing.

Temporal process of zygomatic bone

The temporal process of the zygomatic bone is a bony projection that contributes to the formation of the zygomatic arch, an important structure in the lateral aspect of the skull.

Temporalis muscle

The temporalis is a major muscle of mastication located on the lateral side of the skull. It is a strong, fan-shaped muscle that plays a key role in elevating and retracting the mandible.

Temporofacial division

The temporofacial division is one of the two main divisions of the facial nerve (cranial nerve VII) after it exits the stylomastoid foramen and enters the parotid gland. It is primarily a motor branch that innervates the upper and lateral muscles of facial expression.

Temporomandibular joint

The temporomandibular joint (TMJ) is the synovial joint that connects the mandible (lower jaw) to the temporal bone of the skull. It is one of the most complex joints in the body because it allows both hinge and gliding movements.

Tendinous arch

The term “tendinous arch” can refer to different anatomical structures depending on context, but in head and neck anatomy, it often refers to the tendinous arch of the levator veli palatini or tendinous arches in the orbit or pelvis.

Tendon of lateral rectus muscle

The tendon of the lateral rectus muscle is the fibrous distal portion of the lateral rectus, one of the six extraocular muscles responsible for moving the eye. It attaches the muscle to the sclera of the eyeball.

Tendon of medial rectus muscle

The tendon of the medial rectus muscle is the fibrous distal portion of the medial rectus, one of the six extraocular muscles, which attaches the muscle to the sclera of the eyeball.

Tendon of stapedius muscle

The tendon of the stapedius muscle is the distal fibrous portion of the stapedius, the smallest skeletal muscle in the human body, located in the middle ear. It plays a key role in modulating sound transmission.

Tendon of superior rectus muscle

The tendon of the superior rectus muscle is the distal fibrous portion of the superior rectus, one of the six extraocular muscles, which attaches the muscle to the sclera of the eyeball.

Tendon of tensor tympani muscle

The tendon of the tensor tympani muscle is the distal fibrous portion of the tensor tympani, a small skeletal muscle located in the middle ear that plays a role in dampening sound.

Tendon of tensor veli palatini muscle

The tendon of the tensor veli palatini (TVP) muscle is the distal fibrous portion of this muscle, which plays a key role in tensing the soft palate and opening the pharyngeal (auditory/Eustachian) tube.

Tensor tympani muscle

The tensor tympani is a small skeletal muscle of the middle ear that plays an important role in dampening loud sounds and protecting the inner ear.

Tensor tympani nerve

The tensor tympani nerve is the motor branch of the mandibular nerve (CN V3) that innervates the tensor tympani muscle, the small middle ear muscle responsible for dampening loud sounds.

Tensor veli palatini nerve of mandibular nerve

The tensor veli palatini nerve is the motor branch of the mandibular nerve (CN V3) that innervates the tensor veli palatini muscle, a key muscle of the soft palate.

Tensor veli palatini muscle

The tensor veli palatini (TVP) muscle is a muscle of the soft palate that plays a crucial role in tensing the soft palate and opening the pharyngotympanic (Eustachian) tube. It is unique because it is innervated by the mandibular nerve (CN V3), unlike most other soft palate muscles, which are innervated by the vagus nerve (CN X).

Tensor veli palatini tendon

The tendon of the tensor veli palatini (TVP) muscle is the distal fibrous portion of the muscle that wraps around the pterygoid hamulus and inserts into the palatine aponeurosis of the soft palate. It is crucial for proper soft palate tension and Eustachian tube function.

Tentorial (meningeal) branch of ophthalmic nerve (V1)

The tentorial (meningeal) branch of the ophthalmic nerve (V1) is a small sensory branch of the ophthalmic division of the trigeminal nerve (cranial nerve V1). It is sometimes called the tentorial nerve or nerve of Arnold.

Tentorial artery

The tentorial artery, also known as the artery of Bernasconi and Cassinari, is a branch of the meningohypophyseal trunk of the internal carotid artery (ICA). It is primarily a small dural artery supplying the tentorium cerebelli.

Tentorial branches of meningohypophyseal trunk

The tentorial branches of the meningohypophyseal trunk are small dural arteries that supply the tentorium cerebelli.

Tentorium cerebelli

The tentorium cerebelli is a fold of dura mater that separates the cerebellum from the occipital lobes of the cerebrum. It is one of the major dural reflections in the cranial cavity.

Terminal branches of anterior cerebral artery

The anterior cerebral artery (ACA) is one of the two terminal branches of the internal carotid artery, the other being the middle cerebral artery (MCA). After coursing along the interhemispheric fissure, the ACA gives off several terminal branches that supply the medial and superior aspects of the frontal and parietal lobes.

Terminal branches of posterior cerebral artery

The posterior cerebral artery (PCA) is one of the two terminal branches of the basilar artery (the other being the superior cerebellar artery in some texts, but the basilar artery bifurcates into the two PCAs). The PCA supplies the occipital lobe, inferior temporal lobe, thalamus, midbrain, and posterior corpus callosum. Its terminal branches arise after it courses around the midbrain and along the calcarine sulcus.

Terminal sulcus

The terminal sulcus is an anatomical landmark in the right atrium of the heart, associated with the junction between the sinus venosus and the primitive atrium during development.

Termination of anterior jugular vein

The anterior jugular vein (AJV) is a superficial vein of the neck that primarily drains the anterior region of the neck. Its termination is important for understanding venous drainage and surgical approaches in the neck.

Thalami

The thalami (plural of thalamus) are a pair of large, egg-shaped gray matter structures located in the diencephalon of the brain. They act as the major relay stations for sensory, motor, and limbic information between the brainstem, cerebellum, basal ganglia, and cerebral cortex.

Thalamogeniculate arteries

The thalamogeniculate arteries are small, deep branches of the posterior cerebral artery (PCA) that supply key thalamic and midbrain structures.

Thalamoperforating arteries

The thalamoperforating arteries are small, deep-penetrating arteries that arise mainly from the posterior cerebral artery (PCA) and posterior communicating artery (PComm) to supply the thalamus and adjacent structures. They are crucial for deep brain blood supply.

Thalamotuberal (premammillary) artery

The thalamotuberal artery, also called the premammillary artery, is a small but important perforating artery that arises from the posterior communicating artery (PComm) and supplies key regions of the diencephalon.

Thalamus

The thalamus is a paired, large, egg-shaped gray matter structure located in the diencephalon of the brain. It acts as a major relay and integration center for sensory, motor, and limbic pathways between the brainstem, cerebellum, basal ganglia, and cerebral cortex.

Thoracic cardiac branch of vagus nerve

The thoracic cardiac branches of the vagus nerve are parasympathetic fibers that contribute to the cardiac plexus, helping regulate heart rate and cardiac function.

Thoracic duct

The thoracic duct is the largest lymphatic vessel in the body and is the main channel for returning lymph and chyle from most of the body into the venous system.

Thoracic part of spinal cord

The thoracic part of the spinal cord is the segment of the spinal cord that gives rise to the thoracic spinal nerves (T1–T12). It has distinctive anatomical and functional features compared with cervical or lumbar regions.

Thoracic sympathetic nerves

The thoracic sympathetic nerves are part of the sympathetic division of the autonomic nervous system and arise from the thoracic segments of the spinal cord (T1–T12). They are responsible for innervating the thoracic viscera, blood vessels, and sweat glands.

Thoracic sympathetic trunk ganglion

The thoracic sympathetic trunk ganglia are collections of nerve cell bodies in the thoracic portion of the sympathetic chain, forming part of the autonomic nervous system. They serve as relay stations for sympathetic signals going to thoracic and abdominal organs.

Thoracodorsal artery

The thoracodorsal artery is a branch of the subscapular artery, which itself arises from the axillary artery. It is the main arterial supply to the latissimus dorsi muscle and contributes to the scapular region’s blood supply.

Thyroarytenoid muscle

The thyroarytenoid muscle is an intrinsic muscle of the larynx that plays a key role in voice modulation by adjusting tension of the vocal cords.

Thyrocervical trunk

The thyrocervical trunk is a short, thick arterial branch of the subclavian artery that supplies structures in the neck and upper back, including the thyroid gland, scapula, and surrounding muscles.

Thyroepiglottic ligament

The thyroepiglottic ligament is a fibrous structure of the larynx that connects the epiglottis to the thyroid cartilage, helping stabilize the epiglottis and maintain the laryngeal inlet.

Thyroepiglottic muscle

The thyroepiglottic muscle is a small intrinsic muscle of the larynx, considered part of the thyroarytenoid muscle complex, that helps widen the laryngeal inlet.

Thyrohyoid membrane

The thyrohyoid membrane is a fibroelastic structure connecting the thyroid cartilage to the hyoid bone, forming part of the laryngeal framework and playing a key role in supporting and stabilizing the larynx.

Thyrohyoid muscle

The thyrohyoid muscle is one of the infrahyoid (“strap”) muscles of the neck. It is involved in laryngeal movement during swallowing and speech.

Thyroid articular surface

The thyroid articular surface refers to the part of the thyroid cartilage that articulates with another laryngeal cartilage, most commonly the cricoid cartilage, forming the cricothyroid joint.

Thyroid cartilage

The thyroid cartilage is the largest of the laryngeal cartilages and forms the anterior and lateral walls of the larynx, giving structure and protection to the vocal apparatus.

Thyroid cartilage lamina

The lamina of the thyroid cartilage refers to the two broad, flat plates that make up the lateral walls of the thyroid cartilage. These laminae fuse anteriorly to form the laryngeal prominence.

Thyroid gland

The thyroid gland is a highly vascular endocrine gland in the neck that produces hormones regulating metabolism, growth, and development.

Tip of greater horn of hyoid bone

The tip of the greater horn (cornu) of the hyoid bone refers to the lateral, posterior projection of the hyoid bone that serves as a site for muscle and ligament attachments.

Tongue

The tongue is a muscular organ in the oral cavity that is essential for taste, speech, swallowing, and oral hygiene. It is highly mobile and consists of intrinsic and extrinsic muscles, covered by a mucous membrane with specialized papillae.

Tonsil

The tonsils are lymphoid tissues located in the pharyngeal region that form part of the Waldeyer’s ring, which provides immune defense in the upper respiratory and digestive tracts.

Tonsil of posterior lobe of cerebellum

The tonsil of the posterior lobe of the cerebellum is a rounded lobule on the inferior surface of the cerebellum, part of the cerebellar hemispheres, closely associated with the foramen magnum and medulla oblongata.

Tonsillar artery

The tonsillar artery is an artery that primarily supplies the palatine tonsil. It is a branch of the facial artery, although accessory supply can come from other nearby arteries.

Tonsillar branch of ascending palatine artery

The tonsillar branch of the ascending palatine artery is a small artery that contributes to the blood supply of the palatine tonsil. It is a branch of the ascending palatine artery, which itself arises from the facial artery.

Tonsillar branch of ascending pharyngeal artery

The tonsillar branch of the ascending pharyngeal artery is a small arterial branch that contributes to the blood supply of the palatine tonsil, arising from the ascending pharyngeal artery, a branch of the external carotid artery.

Tonsillar branch of dorsal lingual artery

The tonsillar branch of the dorsal lingual artery is a small arterial branch that supplies the palatine tonsil and nearby structures.

Tonsillar branch of glossopharyngeal nerve

The tonsillar branch of the glossopharyngeal nerve is a sensory nerve branch that supplies the palatine tonsil and nearby areas.

Tonsillar branch of lesser palatine artery

The tonsillar branch of the lesser palatine artery is a small arterial branch that contributes to the blood supply of the palatine tonsil.

Tonsillar branches

The tonsillar branches are a group of arterial and neural branches that supply the palatine tonsil and its surrounding tissues.

Torus levatorius

The torus levatorius is a mucosal ridge in the lateral wall of the nasopharynx formed by the underlying levator veli palatini muscle.

Torus tubarius

The torus tubarius is a prominent mucosal elevation in the nasopharynx caused by the underlying cartilage of the pharyngotympanic (Eustachian) tube.

Trabecula (fibrous tissue)

A trabecula in the context of fibrous tissue refers to a small, beam-like or thread-like band of connective tissue that supports or partitions tissue within an organ.

Trabecular meshwork and spaces of iridocorneal angle (of Fontana)

The trabecular meshwork and the spaces of Fontana are key anatomical structures in the iridocorneal angle of the eye, crucial for aqueous humor drainage.

Trachea

The trachea is a tubular airway connecting the larynx to the bronchi, allowing air passage to the lungs.

Tragus

The tragus is a small, cartilaginous projection on the external ear that partially covers the opening of the external auditory canal.

Transverse and oblique arytenoid muscles

The transverse and oblique arytenoid muscles are intrinsic muscles of the larynx that control the movement of the vocal folds and arytenoid cartilages.

Transverse and vertical of intrinsic muscles of tongue

The intrinsic muscles of the tongue are responsible for changing the shape of the tongue (shortening, flattening, curling, or narrowing it) rather than moving it from place to place. Among them, the transverse and vertical muscles are key for altering tongue shape.

Transverse arytenoid muscle

The transverse arytenoid muscle is an intrinsic muscle of the larynx that plays a key role in adducting the vocal folds.

Transverse cervical artery

The transverse cervical artery is an important branch of the thyrocervical trunk that supplies muscles and structures in the posterior triangle of the neck.

Transverse cervical chain of nodes

The transverse cervical chain of lymph nodes is a group of superficial and deep cervical lymph nodes located along the transverse cervical vessels in the posterior triangle of the neck.

Transverse cervical nerves

The transverse cervical nerves are part of the cervical plexus and are primarily cutaneous nerves that supply the anterior and lateral neck.

Transverse cervical vein

The transverse cervical vein is a venous vessel of the neck that accompanies the transverse cervical artery and drains blood from the posterior neck and shoulder region.

Transverse facial artery

The transverse facial artery is a branch of the superficial temporal artery that supplies facial structures in the lateral region of the face.

Transverse facial vein

The transverse facial vein is a venous structure of the face that runs alongside the transverse facial artery and drains blood from the lateral face into the superficial temporal or retromandibular vein.

Transverse foramen

The transverse foramen is a bony opening in the cervical vertebrae that allows passage of the vertebral artery, vein, and sympathetic nerves. It is a key landmark in cervical spine anatomy.

Transverse ligament of atlas

The transverse ligament of the atlas is a crucial ligament of the atlantoaxial joint that stabilizes the dens (odontoid process) of the axis (C2) against the anterior arch of the atlas (C1).

Transverse occipital sulcus

The transverse occipital sulcus is a groove on the posterior part of the brain, located in the occipital lobe.

Transverse palatine folds

The transverse palatine folds are anatomical features of the hard palate that play a role in oral function and speech.

Transverse part of nasalis muscle

The transverse part of the nasalis muscle is a component of the nasal muscles that compresses the nostrils.

Transverse pontine vein

The transverse pontine vein is a venous structure of the brainstem involved in draining blood from the pons into larger venous channels.

Transverse process

The transverse process is a bony projection from the vertebra that serves as a site for muscle and ligament attachment and, in the cervical region, as a passageway for vertebral vessels.

Transverse process (posterior tubercle)

The posterior tubercle of the transverse process is a specific anatomical feature of cervical vertebrae, part of the bony projection that serves for muscle attachment and vertebral stability.

Transverse process of atlas (C1)

The transverse process of the atlas (C1) is a prominent lateral projection of the first cervical vertebra that serves as a site for muscle attachment and passage for the vertebral artery.

Transverse process of C6

The transverse process of the sixth cervical vertebra (C6) is a prominent lateral bony projection that serves as a landmark for muscle attachment, ligament attachment, and clinical procedures.

Transverse sinus

The transverse sinus is a major dural venous sinus in the brain that drains venous blood from the brain into the sigmoid sinus.

Transverse veins of caudate nucleus

The transverse veins of the caudate nucleus are small veins that drain the caudate nucleus, a part of the basal ganglia, into larger venous channels in the brain.

Trapezius muscle

The trapezius muscle is a large, superficial back and neck muscle involved in movement and stabilization of the scapula and shoulder.

Triangular fold

The term triangular fold usually refers to small folds of mucous membrane in the pharynx or larynx, depending on the context. The most commonly described triangular fold is in the larynx.

Triangular fossa

The triangular fossa is a small, triangular-shaped depression in the external ear (auricle).

Triangular part of inferior frontal gyrus

The triangular part of the inferior frontal gyrus is a specific subdivision of the frontal lobe involved in language, speech, and cognitive functions.

Tributary of superficial temporal vein

The superficial temporal vein is a major venous channel of the scalp that drains the lateral aspect of the head into the retromandibular vein. It receives several tributaries.

Trigeminal (semilunar) ganglion

The trigeminal (semilunar) ganglion is a sensory ganglion of the trigeminal nerve (cranial nerve V) that contains the cell bodies of sensory neurons supplying the face.

Trigeminal impression of petrous part of temporal bone

The trigeminal impression is an anatomical feature of the petrous part of the temporal bone that serves as the site for the trigeminal (semilunar) ganglion).

Trigeminal nerve (V)

The trigeminal nerve is the fifth cranial nerve (CN V) and is the main sensory nerve of the face as well as a motor nerve for mastication.

Trigeminal tubercle

The trigeminal tubercle is an anatomical landmark on the posterolateral aspect of the medulla oblongata related to the trigeminal nerve (CN V).

Trochlea (pulley)

The trochlea in anatomy usually refers to a pulley-like structure in the orbit associated with the superior oblique muscle of the eye.

Trochlear nerve (IV)

The trochlear nerve (cranial nerve IV) is a cranial nerve that innervates the superior oblique muscle of the eye, responsible for intorsion, depression, and abduction of the eyeball.

Trochlear nucleus

The trochlear nucleus is the motor nucleus of cranial nerve IV (trochlear nerve) located in the midbrain, responsible for innervating the superior oblique muscle of the eye.

Tonsil of cerebellum

The tonsil of the cerebellum is a rounded lobule of the cerebellar hemisphere that is part of the posterior lobe of the cerebellum.

Trunk of corpus callosum

The trunk of the corpus callosum is a major subdivision of the corpus callosum, which is the largest commissural fiber bundle connecting the two cerebral hemispheres.

Tubal branch of tympanic plexus

The tubal branch is a branch arising from the tympanic plexus, which is a network of nerves on the promontory of the middle ear. It provides sensory fibers to the pharyngotympanic (Eustachian) tube.

Tuber cinereum

The tuber cinereum is a gray, cone-shaped structure of the hypothalamus that forms part of the floor of the third ventricle.

Tuber of inferior vermis

The tuber of the inferior vermis is a specific part of the cerebellar vermis, located in the posterior lobe of the cerebellum.

Tuber of vermis of cerebellum

The tuber of the vermis is a specific lobule of the cerebellar vermis, part of the posterior lobe of the cerebellum.

Tubercle of superior lip

The tubercle of the superior lip is a small anatomical prominence of the upper lip, often considered in facial anatomy and aesthetics.

Tubercles of transverse process of C3 vertebra

The tubercles of the transverse process of C3 vertebra are small bony prominences located on the anterior and posterior aspects of the transverse process. They are important anatomical landmarks for muscle attachment and neurovascular passage.

Tuberculum sellae of sella turcica of body of sphenoid bone

The tuberculum sellae is an important bony landmark of the sphenoid bone that forms the anterior boundary of the sella turcica.

Tuberohypophyseal tract

The tuberohypophyseal tract is a hypothalamic-pituitary neuroendocrine pathway that carries hormones from the hypothalamus to the anterior pituitary.

Tuberosity of maxilla

The tuberosity of the maxilla is a prominent anatomical feature of the posterior part of the upper jaw that serves as an important site for muscle attachment and dental anatomy.

Tufted cell

A tufted cell is a specific type of neuronal cell found in the olfactory bulb, involved in the processing of olfactory (smell) information.

Tympanic

The term “tympanic” generally refers to anything related to the tympanum (middle ear). It can describe structures, nerves, arteries, or cavities associated with the middle ear.

Tympanic branch of glossopharyngeal nerve (IX) of Tympanic canaliculus

The tympanic branch of the glossopharyngeal nerve (CN IX), also called the tympanic nerve, is an important nerve that contributes to the tympanic plexus in the middle ear.

Tympanic canaliculus of temporal bone

The tympanic canaliculus is a small bony canal in the temporal bone that serves as a passageway for the tympanic branch of the glossopharyngeal nerve (CN IX) and accompanying vessels.

Tympanic cavity

The tympanic cavity is a central part of the middle ear and plays a key role in hearing and sound transmission.

Tympanic cells

Tympanic cells are part of the mastoid air cell system in the temporal bone, connected to the tympanic cavity.

Tympanic membrane

The tympanic membrane (commonly called the eardrum) is a thin, semi-transparent membrane that separates the external ear from the middle ear and plays a crucial role in hearing.

Tympanic membrane (pars tensa)

The pars tensa is the largest and tense portion of the tympanic membrane, primarily responsible for transmitting sound vibrations to the ossicles.

Tympanic nerve

The tympanic nerve is a branch of the glossopharyngeal nerve (cranial nerve IX) that plays a key role in sensory innervation of the middle ear and parasympathetic innervation to the parotid gland.

Tympanic part of temporal bone

The tympanic part of the temporal bone is a portion of the temporal bone that contributes to the walls of the external acoustic (auditory) canal and the floor of the tympanic cavity. It’s closely associated with the ear structures and plays a key role in hearing.

Tympanic plexus

The tympanic plexus is a network of nerves located on the promontory of the middle ear (tympanic cavity) that plays a key role in autonomic innervation of the middle ear, inner ear, and nearby glands.

Tympanic plexus on promontory

The tympanic plexus on the promontory refers specifically to the nerve network that lies over the bony prominence (promontory) on the medial wall of the middle ear.

Umbo

In anatomy, the umbo refers to the central, most depressed point of the tympanic membrane (eardrum) where the tip of the malleus (umbo of malleus) attaches. It is a key landmark in otology and is important for sound transmission from the external ear to the middle ear.

Uncal vein

The uncal vein is a cerebral vein that drains the uncus of the temporal lobe, a medial part of the anterior temporal lobe near the parahippocampal gyrus. It is part of the superficial venous system of the brain and typically drains into larger veins such as the basal vein (of Rosenthal) or great cerebral vein (vein of Galen).

Uncinate process of ethmoid bone

The uncinate process is a hook-shaped anatomical projection found in different regions of the body, but most commonly referred to in two contexts: the lung (bronchial anatomy) and the ethmoid bone (paranasal sinus anatomy).

Uncinate processes

The term “uncinate processes” refers generally to hook-shaped projections in anatomy. The two main contexts where this term is commonly used are the ethmoid bone (nasal cavity) and the pancreas.

Uncovertebral articulations

The uncovertebral articulations (also called Luschka’s joints) are synovial-like joints in the cervical spine formed between the uncinate processes of the cervical vertebrae and the vertebral bodies above. They are unique to the cervical region (C3–C7) and play a role in stabilizing the cervical spine and guiding its movement.

Uncovertebral joints

The uncovertebral joints (also called joints of Luschka) are unique anatomical structures found in the cervical spine, specifically from C3 to C7. They are not true synovial joints but are often described as pseudo-joints because of their structure and function.

Uncus

In anatomy, the term uncus generally refers to a hook-shaped structure, and its meaning depends on the context.

Upper 1st molar

The upper first molar (also called maxillary first molar) is a key tooth in the permanent dentition and has distinctive features important in dentistry and anatomy.

Upper 1st premolar

The upper first premolar (also called maxillary first premolar) is a tooth in the permanent dentition with unique anatomy and clinical importance.

Upper 2nd molar

The upper second molar (maxillary second molar) is an important tooth in the permanent dentition, located posteriorly in the maxilla.

Upper 2nd premolar

The upper second premolar (maxillary second premolar) is a tooth in the permanent dentition with slightly different anatomy compared to the first premolar.

Upper 3rd molar

The upper third molar (maxillary third molar), often called the wisdom tooth, is the most posterior tooth in the upper jaw.

Upper canine

The upper canine (maxillary canine) is a key tooth in the permanent dentition with distinctive anatomy and function.

Upper central incisor

The upper central incisor (maxillary central incisor) is one of the most prominent teeth in the permanent dentition.

Upper cervical vertebrae

The upper cervical vertebrae refer to the first two cervical vertebrae (C1 and C2) and, in some contexts, also include C3. These vertebrae have unique features that distinguish them from the lower cervical and thoracic vertebrae.

Upper lateral incisor

The upper lateral incisor (maxillary lateral incisor) is an anterior tooth located next to the central incisor in the upper jaw.

Utricle

The utricle is a key structure in the inner ear, part of the vestibular system, which is responsible for balance and spatial orientation.

Uvula

The uvula is a small, conical structure that hangs down from the posterior edge of the soft palate in the oral cavity.

Uvula of inferior vermis

The uvula of the inferior vermis is a specific lobule of the cerebellum.

Uvula of vermis of cerebellum

The uvula of the vermis is a lobule of the cerebellar vermis, which is the midline structure of the cerebellum connecting the two hemispheres.

Uvular muscle

The uvular muscle (or musculus uvulae) is a small intrinsic muscle of the soft palate, specifically forming the body of the uvula.

Vagal cardiac nerves

The vagal cardiac nerves are parasympathetic branches of the vagus nerve (cranial nerve X) that contribute to the cardiac plexus, helping regulate heart rate, conduction, and cardiac function.

Vagal fibers

Vagal fibers are the axonal components of the vagus nerve (cranial nerve X) that carry motor, sensory, and parasympathetic signals to a wide range of structures in the head, neck, thorax, and abdomen. They are a key part of the autonomic and sensory innervation system.

Vagal trigone

The vagal trigone is a triangular area on the floor of the fourth ventricle of the brainstem that represents the surface landmark of the dorsal motor nucleus of the vagus nerve (cranial nerve X). It is part of the medullary floor and indicates the location of the vagus nerve’s parasympathetic nucleus.

Vagus (X) nerve

The vagus nerve (cranial nerve X) is a mixed cranial nerve with motor, sensory, and parasympathetic fibers, playing a critical role in autonomic regulation, swallowing, speech, and visceral sensation. It is the longest cranial nerve, extending from the medulla oblongata to thoracic and abdominal organs.

Vagus nerve (X) and superior cervical cardiac branch

The vagus nerve (cranial nerve X) gives off several branches that contribute to cardiac innervation, including the superior cervical cardiac branches. These branches carry parasympathetic fibers that participate in regulating heart rate and conduction.

Vagus nerve (X) and sympathetic trunk

The vagus nerve (cranial nerve X) and the sympathetic trunk are both part of the autonomic nervous system, but they carry different types of autonomic fibers and interact in areas like the cardiac, pulmonary, and esophageal plexuses.

Vagus nerve (X) of jugular foramen

The vagus nerve (cranial nerve X) at the jugular foramen refers to the portion of the nerve as it exits the skull through the jugular foramen, carrying motor, sensory, and parasympathetic fibers to the neck, thorax, and abdomen. This is a critical anatomical landmark because several cranial nerves and vascular structures pass through or near this foramen.

Vagus nerve (X) of jugular fossa

The vagus nerve (cranial nerve X) at the jugular fossa refers specifically to the segment of the nerve as it exits the skull through the jugular fossa, the bony depression forming part of the jugular foramen. This is essentially the cranial root of CN X before it enters the neck, and it carries all the motor, sensory, and parasympathetic fibers of the vagus nerve.

Vallate papillae

Vallate papillae (also called circumvallate papillae) are a type of taste papilla located on the dorsal surface of the tongue, specialized for gustation (taste sensation). They are the largest papillae and are involved primarily in bitter taste perception.

Vallecula

The vallecula is a depression or space located in the oropharyngeal region, important in swallowing and airway management.

Vascular supply of eye

The vascular supply of the eye is a complex system that ensures oxygenation and nutrient delivery to the retina, optic nerve, choroid, and other ocular structures. It is primarily derived from the ophthalmic artery, a branch of the internal carotid artery, with contributions from the ciliary arteries, central retinal artery, and vortex veins for venous drainage.

Vein of lateral recess of 4th ventricle

The vein of the lateral recess of the fourth ventricle is a small cerebral vein associated with the lateral recess (foramen of Luschka) of the fourth ventricle. It is part of the venous drainage system of the brainstem and cerebellum.

Veins draining scleral venous sinus (into anterior ciliary veins)

The scleral venous sinus, also known as the canal of Schlemm, is the primary aqueous humor drainage pathway from the anterior chamber of the eye. The veins draining the scleral venous sinus connect it to the episcleral and anterior ciliary venous system, allowing aqueous humor to enter the systemic venous circulation.

Veins of iris

The veins of the iris are part of the venous drainage system of the anterior uveal tract. They collect blood from the iris stroma and drain it into the ciliary veins, which then connect to the episcleral veins and ultimately the ophthalmic veins.

Veins of orbit and eyelids

The veins of the orbit and eyelids form a rich venous network that drains blood from the eye, orbit, and periorbital structures into the cavernous sinus, pterygoid plexus, and facial veins. They are clinically important because of the potential for infection to spread from the face to the brain (“danger triangle”).

Veins of posteriori cranial fossa

The veins of the posterior cranial fossa form a complex venous network draining the cerebellum, brainstem, and occipital lobes into the dural venous sinuses. They include cerebellar veins, brainstem veins, and emissary veins, many of which communicate with extracranial veins.

Veins of vertebral column

The veins of the vertebral column form a valveless venous network that provides venous drainage of the vertebrae, spinal cord, and surrounding structures, and communicates with both intracranial and systemic veins, allowing bidirectional blood flow. This system is clinically important because it can serve as a route for metastatic spread or infection.

Vena comitans of hypoglossal nerve (to lingual vein)

The vena comitans of the hypoglossal nerve is a small accompanying vein that runs alongside the hypoglossal nerve (cranial nerve XII) and drains into the lingual vein, contributing to the venous drainage of the tongue.

Vena comitans of hypoglossal nerve

The vena comitans of the hypoglossal nerve is a small vein that accompanies the hypoglossal nerve (cranial nerve XII) along its course, primarily in the neck and submandibular region, and participates in venous drainage of the tongue and surrounding structures.

Venae comitantes

The vena comitans (plural venae comitantes) is a vein that closely accompanies an artery, usually in pairs or more, along its course. The key idea is that these veins run alongside an artery rather than independently.

Venous plexus of vertebral artery

The venous plexus of the vertebral artery is a network of veins that surrounds the vertebral artery along its course in the neck. These veins are essentially venae comitantes (accompanying veins) that form a plexus, rather than being a single vein.

Ventral posterolateral

The ventral posterolateral nucleus (VPL) is a specific nucleus of the thalamus that plays a key role in sensory processing.

Ventral anterior

The ventral anterior (VA) nucleus is a nucleus of the thalamus that plays a critical role in motor control.

Ventral intermedial

The ventral intermediate (VIM) nucleus is a specific thalamic nucleus that is primarily involved in motor coordination, especially in relation to the cerebellum.

Ventral lateral

The ventral lateral (VL) nucleus is a motor-related nucleus of the thalamus that plays a critical role in coordinating and relaying motor information from subcortical structures to the cerebral cortex.

Ventral posterior

The ventral posterior (VP) nucleus is a major sensory relay nucleus of the thalamus. It is responsible for transmitting somatosensory information from the body and face to the cerebral cortex.

Ventral posteromedial

The ventral posteromedial (VPM) nucleus is a thalamic nucleus that serves as a key sensory relay center for the face and head. It is part of the ventral posterior (VP) complex of the thalamus.

Ventral posteromedial nucleus of thalamus

The ventral posteromedial (VPM) nucleus of the thalamus is a sensory relay nucleus that specifically processes somatosensory information from the face and head. It is part of the ventral posterior (VP) complex of the thalamus.

Ventral rami of C1, C2, C3 for ansa cervicalis of cervical plexus

The ansa cervicalis is a loop of nerves in the cervical plexus that innervates most of the infrahyoid (“strap”) muscles of the neck. Its fibers come from the ventral rami of C1, C2, and C3 spinal nerves.

Ventral ramus

The ventral ramus is one of the two primary branches of a spinal nerve after it exits the intervertebral foramen. It plays a major role in innervating the body wall and limbs.

Ventral root

The ventral root is one of the two roots of a spinal nerve that emerges from the spinal cord and carries motor signals from the central nervous system to the body.

Ventricle

A ventricle is a chamber or cavity within the body. The term is most commonly used in the brain and the heart.

Ventricles of brain

The ventricles of the brain are a system of fluid-filled cavities within the brain that contain cerebrospinal fluid (CSF). They help protect the brain, provide buoyancy, and circulate nutrients and waste.

Ventromedial nuclei of hypothalamus

The ventromedial nucleus (VMN or VMH) of the hypothalamus is a key hypothalamic nucleus involved in regulating feeding behavior, satiety, and metabolism.

Vermis of cerebellum

The vermis is a key structure of the cerebellum that acts as the midline connecting region between the two cerebellar hemispheres.

Vertebra prominens

The vertebra prominens refers to a specific cervical vertebra that is easily palpable at the base of the neck due to its long spinous process.

Vertebral arteries

The vertebral arteries are major paired arteries that supply the posterior part of the brain, including the brainstem, cerebellum, and posterior cerebral hemispheres.

Vertebral bodies

The vertebral bodies are the large, anterior, weight-bearing portions of the vertebrae that make up the main column of the spine. They are key structural units of the vertebral column.

Vertebral canal

The vertebral canal (also called the spinal canal) is the bony passage formed by the vertebrae that houses and protects the spinal cord and its coverings.

Vertebral foramen

The vertebral foramen is the central opening in a single vertebra through which the spinal cord passes. When the vertebrae are stacked together, the vertebral foramina form the vertebral canal.

Vertebral ganglion

The vertebral ganglion refers to a collection of nerve cell bodies (a ganglion) located along the vertebral column, typically associated with the sympathetic nervous system. Most commonly, the term refers to the sympathetic (paravertebral) ganglia of the sympathetic chain.

Vertebral plexus

The vertebral plexus refers to a network of veins (venous plexus) surrounding the vertebral column and spinal cord. It plays an important role in venous drainage and collateral circulation.

Vertical and transverse muscles of tongue

The vertical and transverse muscles of the tongue are intrinsic muscles, meaning they are entirely contained within the tongue and do not attach to bone. These muscles are responsible for shaping and precise movements of the tongue rather than moving it as a whole.

Vessels of internal sheath of optic nerve

The internal (intraneural) sheath of the optic nerve contains blood vessels that supply and drain the optic nerve itself. These vessels are essential for the nutrition of the optic nerve fibers and their supporting glial tissue.

Vestibular

In anatomy, the term “vestibular” refers to structures or functions related to balance, equilibrium, and spatial orientation, usually associated with the inner ear and the nervous system.

Vestibular (Reissner's) membrane

The vestibular membrane, also called Reissner’s membrane, is a thin, delicate membrane inside the cochlea of the inner ear. It plays an essential role in hearing by separating fluid-filled chambers.

Vestibular area

The vestibular area is an anatomical region on the floor of the fourth ventricle in the brainstem, specifically on the lateral part of the rhomboid fossa, that overlies the vestibular nuclei.

Vestibular ganglion

The vestibular ganglion, also called the Scarpa’s ganglion, is a sensory ganglion of the vestibular division of the vestibulocochlear nerve (cranial nerve VIII). It contains the cell bodies of primary sensory neurons that carry balance (equilibrium) information from the inner ear to the brainstem.

Vestibular nerve

The vestibular nerve is the balance (equilibrium) division of the vestibulocochlear nerve (cranial nerve VIII). It carries sensory information about head position and movement from the inner ear to the brainstem.

Vestibular nuclei

The vestibular nuclei are a group of four paired sensory nuclei located in the brainstem (pons and medulla) that receive balance information from the vestibular nerve and help control posture, balance, and eye movements.

Vestibule

The term “vestibule” in anatomy refers to a small entrance chamber or cavity that serves as a gateway into a larger space.

Vestibulocochlear nerve (VIII)

The vestibulocochlear nerve (cranial nerve VIII) is a sensory cranial nerve responsible for hearing and balance.

Vestigial remnant of Rathke's pouch

The vestigial remnant of Rathke’s pouch refers to small leftover tissue from Rathke’s pouch, an embryonic structure that gives rise to the anterior pituitary gland (adenohypophysis).

Vitreous body

The vitreous body is a clear, gel-like substance that fills the posterior segment of the eyeball—the large space between the lens and the retina. It helps maintain the eye's shape and keeps the retina pressed gently against the choroid.

Vitreous chamber

The vitreous chamber is the largest compartment of the eyeball, located between the lens and the retina, and it is filled with the vitreous body (vitreous humor).

Vocal fold

The vocal fold (commonly called the vocal cord) is a paired structure in the larynx that is essential for voice production.

Vocal ligaments

The vocal ligaments are fibrous bands within the vocal folds (true vocal cords) of the larynx that provide structural support and elasticity essential for voice production.

Vocal process

The vocal process is a bony projection on the arytenoid cartilage of the larynx to which the vocal ligament attaches. It plays a key role in voice production by anchoring the vocal folds.

Vocalis and thyroarytenoid muscles

The vocalis and thyroarytenoid muscles are intrinsic muscles of the larynx that play a critical role in voice production, pitch modulation, and vocal fold tension. They are closely related anatomically and functionally.

Vocalis muscle

The vocalis muscle is a small, intrinsic muscle of the larynx that lies medial to the thyroarytenoid muscle and is closely associated with the vocal ligament. It plays a critical role in fine control of voice.

Vomer

The vomer is a thin, flat bone in the midline of the skull that forms part of the nasal septum. It helps divide the nasal cavity into right and left halves.

Vomerine groove (for nasopalatine nerve and vessels)

The vomerine groove is a groove on the anterior surface of the vomer bone that serves as a passageway for the nasopalatine nerve and accompanying vessels.

Vorticose (choroid) vein

A vorticose vein, also called a vortex vein or choroidal vein, is a large venous vessel in the eye that drains blood from the choroid (the vascular layer of the eye) into the scleral venous sinus or vortex venous system.

White rami communicans

The white rami communicantes are structures of the autonomic nervous system that connect spinal nerves to the sympathetic trunk (chain ganglia).

Wing of central lobule of anterior lobe of cerebellum

The wing of the central lobule of the anterior lobe of the cerebellum is a specific part of the cerebellar vermis and hemispheres.

Zone of sparse muscle fibers

The zone of sparse muscle fibers is a specialized anatomical term most commonly used in reference to extraocular muscles, specifically the superior oblique and inferior oblique muscles, or in the palatal muscles, depending on context.

Zonular fibers

Zonular fibers (also called suspensory ligaments of the lens) are key structures in the eye that connect the ciliary body to the lens, allowing the lens to change shape for focusing.

Zonular fibers (suspensory ligament of lens)

The zonular fibers, also called the suspensory ligaments of the lens, are fine fibrous structures in the eye that connect the ciliary body to the lens, playing a crucial role in lens suspension and accommodation.

Zygapophyseal (facet) joints

The zygapophyseal joints, also called facet joints, are synovial joints located between the articular processes of adjacent vertebrae. They play a crucial role in spinal stability and movement.

Zygapophyseal joints (C4-5 and C5-6)

The zygapophyseal (facet) joints at the C4–C5 and C5–C6 levels are part of the cervical spine and are important for neck mobility and stability.

Zygomatic arch

The zygomatic arch is a prominent bony structure of the face formed by the zygomatic bone and the temporal bone. It plays a key role in facial contour, muscle attachment, and protection of neurovascular structures.

Zygomatic bone

The zygomatic bone (cheekbone or malar bone) is a paired facial bone that forms the prominence of the cheek and contributes to the orbit, zygomatic arch, and facial contour.

Zygomatic branches

The zygomatic branches are branches of the facial nerve (cranial nerve VII) that supply muscles of facial expression in the cheek and lateral orbit.

Zygomatic nerve

The zygomatic nerve is a branch of the maxillary division (V2) of the trigeminal nerve (cranial nerve V). It is primarily sensory and supplies the lateral face and orbit.

Zygomatic process of maxilla

The zygomatic process of the maxilla is a bony projection of the maxilla that contributes to the prominence of the cheek and forms part of the zygomatic arch.

Zygomatic process of temporal bone

The zygomatic process of the temporal bone is a bony projection of the temporal bone that, together with the zygomatic process of the maxilla, forms the zygomatic arch.

Zygomatic recesses of maxillary sinus

The zygomatic recesses of the maxillary sinus are superolateral extensions of the maxillary sinus, located near the zygomatic bone.

Zygomaticofacial artery

The zygomaticofacial artery is a small branch of the zygomatic artery, itself a branch of the maxillary artery, supplying the lateral face.

Zygomaticofacial foramen of zygomatic bone

The zygomaticofacial foramen is a small opening on the zygomatic bone that allows passage of the zygomaticofacial nerve and artery.

Zygomaticofacial nerve of maxillary nerve

The zygomaticofacial nerve is a sensory branch of the maxillary nerve (V2, cranial nerve V) that supplies the skin over the lateral cheek.

Zygomaticofacial vein

The zygomaticofacial vein is a venous vessel that accompanies the zygomaticofacial artery and nerve over the lateral cheek.

Zygomaticoorbital artery

The zygomaticoorbital artery is a branch of the zygomatic artery, itself originating from the maxillary artery, supplying structures in the lateral orbit.

Zygomaticoorbital vein

The zygomaticoorbital vein is a venous vessel associated with the zygomaticoorbital artery, draining the lateral orbit and connecting with facial and orbital venous networks.

Zygomaticotemporal nerve of maxillary nerve

The zygomaticotemporal nerve is a sensory branch of the maxillary nerve (V2, cranial nerve V) that supplies the temporal region of the scalp.

Zygomaticus major muscle

The zygomaticus major muscle is a muscle of facial expression responsible for elevating the angle of the mouth, producing a smile.

Zygomaticus minor muscle

The zygomaticus minor muscle is a muscle of facial expression that assists in elevating the upper lip, contributing to expressions like smiling or showing the teeth.

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