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Antihelix (ear)

The antihelix of the ear refers to the Y-shaped cartilage within the external ear, it lies next to the scapha of the ear, the ridge separating the helix from the antihelix. Gross anatomy The antihelix can be divided into two parts bifurcating around the triangular fossa1: superior crus: upper...

Vertebral arteria lusoria

Vertebral arteria lusoria is an extremely rare anatomical variant of the aortic arch, whereby the right vertebral artery arises from the aorta distal to the left subclavian artery 1. The aberrant right vertebral artery has a retro-esophageal and retrotracheal course before entering a cervical tr...

Helix (ear)

The helix of the ear refers to the cartilaginous rim of the auricle. It can be divided into three parts 1: ascending: beginning from the root at the scalp, extending vertically superior: begins at the end of the ascending portion when the helix curves and ends at the Darwin tubercle, a thicke...

Normal variant of femoral condyle ossification

Normal variant of femoral condyle ossifications occurs due to variability of endochondral ossification of articular cartilage and can be easily confused with osteochondritis dissecans. Epidemiology more often in boys (mean age of ~8 years) than in girls 1 often bilateral 1,2 typically locat...

Rectus capitis lateralis muscle

The rectus capitis lateralis muscle is an integral component of the prevertebral muscle group, which plays a pivotal role in head movement and serves as a vital surgical landmark. Summary origin: superior transverse processes of the atlas insertion: inferior to the jugular processes of the oc...

Antitragicus muscle

The antitragicus muscle is an intrinsic muscle of the outer ear that is part of the broader auricular muscle group. Summary origin: posterior surface of the antitragus insertion: tail of the helix innervation: posterior auricular branch of the facial nerve action: assists in ear...

Tragus

The tragus is a small, cartilaginous projection situated anteriorly to the external auditory meatus. Relations The tragus is positioned anteriorly to the external auditory meatus and is surrounded by other components of the external ear, including the antitragus and the helix. Arterial Supply...

Tragicus muscle

The tragicus muscle is an intrinsic muscle of the outer ear that facilitates the opening of the external auditory canal and assists in minor movement of the tragus. Summary: origin: base of tragus insertion: apex of tragus blood supply: branches of facial arteries innervation: f...

Helicis minor muscle

The helicis minor muscle is a small, intrinsic auricular muscle responsible for shaping the anterior margin of the ear. Summary origin: base of the helix of the ear insertion: anterior helix blood supply: branches of the facial arteries innervation: posterior and temporal auricular nerves o...

Accessory hepatic sulci

Accessory hepatic grooves (interchangeably referred as accessory hepatic fissures or accessory hepatic sulci) are a common variant, with majority of accessory grooves occurring over the diaphragmatic surface of the liver 1,2. Several hypotheses have been made regarding the process by which an a...

Helicis major muscle

The helicis major muscle is an intrinsic auricular muscle that plays a vestigial role in adjusting the shape of the ear. Summary origin: root of the helix of the ear insertion: anterior border of the helix blood supply: anterior auricular branches of the superficial temporal artery and other...

Mental spines

Mental spines are small, midline, paired, bony protuberances (or eminences) of the posterior lingual surface of the mandible. There are usually two superior and two inferior spines. They represent the anchor points of origin of the superior genioglossus and the inferior geniohyoid muscles 1,2. C...

Ligaments of the larynx

The ligaments of the larynx can be considered as two groups based on whether they attach components of the larynx together internally or externally. Gross anatomy Extrinsic ligaments thyrohyoid membrane median thyrohyoid ligament lateral thyrohyoid ligament hyoepiglottic ligament cricothy...

Rima vestibuli

The rima vestibuli is the V-shaped space formed between the false vocal cords, which allows the passage of air through the larynx. It is larger and located superior to the rima glottidis. It should not be confused for the laryngeal vestibule, which is the entire open space of the supraglottis b...

Rima glottidis

The rima glottidis is the V-shaped opening formed between the true vocal cords, which permits the passage of air through the larynx. Abduction or adduction of the vocal cords can open or close the rima glottidis. The rima glottidis constitutes part of the glottic region of the larynx. It should...

Lumbar veins

The lumbar veins are paired segmental veins that drain structures of the back and posterior abdominal wall. They are the venous complement of the lumbar arteries. They primarily drain into the inferior vena cava and ascending lumbar veins. Gross anatomy There are usually four pairs of lumbar v...

Spiral mucosal folds

The spiral mucosal folds, also known as the valves of Heister, are spirally arranged mucosal folds on the endoluminal surface of the cystic duct. Although incompletely understood, they contain neurohormonally responsive muscle, and their unique shape is thought to support the patency of the cys...

Obturator fascia

The obturator fascia is the fascia of the obturator internus muscle which covers its internal surface and attaches to the bony margins of the obturator foramen. Superomedially, the obturator fascia gives way to the obturator canal, allowing the obturator artery, vein and nerve to communicate b...

Palmar carpal ligament

The palmar carpal ligament (also known as the volar carpal ligament) is a fibrous structure that forms the roof of Guyon's canal. Proximally, it is continuous with the deep fascia of the forearm and attaches to the pisiform, pisiform ligamentous complex and a leaf of the flexor retinaculum over...

Anal columns

The anal columns, also known as columns of Morgagni are a number of longitudinal folds of the anal mucosa. The columns unite inferiorly to form crescentic shaped anal valves. Shallow clefts of mucosa are formed in between the columns and valves, termed the anal sinuses. The anal valves form a c...

Venous drainage of the upper limb

The venous drainage of the upper limb is highly variable, however the anatomy by which the veins drain the upper limb can be broadly divided into superficial and deep venous systems 1. Superficial venous system cephalic vein accessory cephalic vein basilic vein median cubit...

Deep palmar arch

The deep palmar arch is the terminal branch of the radial artery, usually forming an anastomosis with the ulnar artery 1. The radial artery enters the palm in between the oblique and transverse heads of adductor pollicis muscle, coursing across the palm approximately 1 cm proximal to the superf...

Submandibular gland agenesis

Submandibular gland agenesis, also known as aplasia, is the absence of one or both of the submandibular glands and is rare. Epidemiology Only forty cases of submandibular gland agenesis had been reported in the English literature up to 2014 3. Associations It has been found that aplasia of m...

Pancreatoduodenal space

The pancreaticoduodenal space (PDS) or groove (PDG) is a small anatomical potential space between the pancreatic head and duodenum 1. Gross anatomy Boundaries medial: pancreatic head lateral: 2nd portion of duodenum superior: duodenal bulb inferior 3rd portion of duodenum posterior: infer...

Dorsolateral fasciculus

The dorsolateral fasciculus (also known as Lissaeur's tract or the posterolateral tract) is a bundle of white matter fibers within the posterolateral spinal cord. Summary The dorsolateral fasciculus lies between the apex of the dorsal grey matter and the surface of the cord, surrounding the af...

APUD cells

APUD (Amine Precursor Uptake and Decarboxylation) cells include a wide range of endocrine cell types scattered throughout the body, such as the respiratory system, gastroenteropancreatic system, reproductive system, thyroid gland, pancreatic islets, adrenal medulla, carotid body, kidney, pituita...

Locus coeruleus

The locus coeruleus is a paired pigmented brainstem nucleus and the brain's main noradrenergic nucleus. It is located in the posterior rostral pons near the lateral floor of the fourth ventricle and is the leading site of norepinephrine synthesis in the brain. Locus coeruleus neurons densely i...

Artery of Davidoff and Schechter

The artery of Davidoff and Schechter is the only dural radicle of the posterior cerebral artery (PCA) and supplies parts of the falx cerebri and tentorium cerebelli 1. Summary origin: either the P1 or P2 segment of the PCA course: inferior to the superior cerebellar artery and superior to the...

Inferior tympanic artery

The inferior tympanic artery is a small branch of the ascending pharyngeal artery that supplies the tympanic cavity. Summary origin: proximal neuromeningeal trunk of ascending pharyngeal artery course: passage through tympanic canaliculus termination: anastomosis with caroticotympanic arter...

Periosteum

The periosteum is a thin membrane of connective tissue composed of different layers covering the surface of a bone, providing structural integrity and contributing to growth and development as well as the repair of bone 1-3. Gross anatomy The periosteum consists of different layers in particul...

Ganglion

A ganglion (plural: ganglia) is a group of neuronal cell bodies and processes located in the peripheral nervous system 1. Ganglia can be categorized into two groups - sensory ganglia and autonomic ganglia. Sensory ganglia primarily contain the cell bodies of neurons as well as their central an...

Posterior meniscofemoral ligament (of Wrisberg)

The posterior meniscofemoral ligament or ligament of Wrisberg is one of the two variably present bands of the meniscofemoral ligament. Gross anatomy The posterior meniscofemoral ligament has insertions proximally at the lateral intercondylar aspect of the medial femoral condyle and distally a...

Subarachnoid lymphatic-like membrane

The subarachnoid lymphatic-like membrane (SLYM) is a recently discovered fourth meningeal layer which compartmentalizes the subarachnoid space into two functional compartments. Gross anatomy The subarachnoid lymphatic-like membrane is only a few cells thin layer, which renders it invisible usi...

Omphalomesenteric duct

The omphalomesenteric duct, also called the vitelline or vitellointestinal duct, is a communicating tract between the embryonic yolk sac and the primitive midgut. This duct is obliterated at around the 5th to 8th week of gestation. Approximately 2% of people have a failure of involution. Relat...

White line of Toldt

The white line of Toldt is a line formed at the junction of the lateral reflection of the posterior parietal peritoneum and the visceral peritoneum of the colon in the paracolic gutter. This represents an avascular plane used to mobilize the right and left hemicolon during hemicolectomy and is ...

Cerebral arteries

Cerebral arteries refers to the three paired main arteries that supply the brain. anterior cerebral arteries (ACAs) middle cerebral arteries (MCAs) posterior cerebral arteries (PCAs) The anterior and middle cerebral arteries arise as terminal branches of the internal carotid arteries. The p...

Superior clunal nerve

The superior clunal nerve is a sensory nerve that originates from the dorsal rami of T11 – L4. The nerve travels obliquely across the buttock. It penetrates thoracolumbar fascia at the iliac crest 1-3. Approximately, half of the nerve fibers travel within an osteofibrous tunnel of the iliac cre...

Intertransversarii muscle group

The intertransversarii muscles are small and short muscles found in the deepest layer of the intrinsic back muscles extending between the transverse processes of adjacent cervical and lumbar vertebrae. The cervical intertransversarii are subdivided into seven pairs of anterior and posterior musc...

Interspinales muscles

The interspinales muscles are a group of paired muscle fascicles found in the paraspinal portion of the deepest layer of the intrinsic back muscles. Gross anatomy The interspinales muscles extend between the spinous processes of two neighboring vertebrae. They are present throughout the entir...

Rectus capitis anterior muscle

The rectus capitis anterior muscle is a short muscle that belongs to the prevertebral and anterior neck muscles. It is located anterior to the vertebral column and stretches between the atlas and the base of the skull. Summary origin: lateral mass and transverse process of atlas (C1) insertio...

Middle clunal nerve

The middle clunal nerve is a sensory nerve that originates from S1-S4 1. It travels underneath the long posterior sacroiliac ligament (LPSL) and passes between the posterior superior iliac spine and posterior inferior iliac spine to course over the iliac crest 1. It supplies sensation to the lum...

Os interphalangeus

Os interphalangeus is an ossicle present in the plantar aspect of interphalangeal joint of great toe 1. The ossicle can be present either centrally or eccentrically within the joint capsule and is separated from the flexor hallucis longus tendon by a bursa. Radiographic features Plain radiogra...

Depressor supercilii muscle

The depressor supercilii is a facial muscle found medial to the orbits and acts as a depressor of the eyebrow. Terminology Ongoing debate exists regarding the exact designation of this muscle. Some anatomy sources view it as part of the orbicularis oculi muscle while others (Cook et. al) sugge...

Extensor indicis proprius

The extensor indicis propius (EIP) muscle is one of the muscles of the posterior deep compartment of the forearm. It is involved in the extension of the second digit at the metacarpophalangeal and interphalangeal joints 1. Summary origin: posterior surface of ulna and interosseous membrane in...

Foramen cecum (tongue)

The foramen cecum of the tongue is the remnant of thyroglossal duct located between the anterior two-thirds and posterior third of the tongue. Gross anatomy The foramen cecum is located in the midline on the surface of the tongue, at the apex of the terminal sulcus, the groove that marks the ...

Metopic ridge

A metopic ridge refers to a variation in skull shape, characterized by a midline forehead ridge, which may occur either due to the physiological closure of the metopic suture or as a result of craniosynostosis of this suture 1-3. It is essential to differentiate between the two conditions becaus...

Adductor hiatus

The adductor hiatus is an opening between the adductor magnus muscle and the femur. It is also known as the hiatus magnus. Gross Anatomy adductor hiatus represents the distal end of the adductor canal it is the anatomical landmark where the femoral artery and vein transition to become the pop...

Ciliary body (eye)

The ciliary body is the continuation of the uveal layer of the eye and functions in the production of aqueous humor and the process of lens accommodation. Summary location: between the vitreous body and posterior chamber of the globe function: aqueous humor production and accommodation...

Posterior meningeal artery

The posterior meningeal artery is the largest artery supplying the dura of the posterior cranial fossa. It may arise from the ascending pharyngeal artery, or less commonly, the occipital artery. The artery may enter the cranial vault through the jugular foramen, foramen magnum or the hypoglossal...

Thoracic splanchnic nerves

The thoracic splanchnic nerves are three paired autonomic nerves that provide sympathetic innervation of the abdominopelvic viscera and vessels. They contain efferent and afferent fibers. Gross anatomy Three pairs of thoracic splanchnic nerves arise from the T5 to T12 sympathetic ganglia. Gre...

Somatic nervous system

The somatic nervous system (SNS) is a subdivision of the peripheral nervous system which provides innervation to the somatic structures of the body, that is the parts excluding the viscera, smooth muscle, and glands. The SNS is distributed throughout the body through somatosensory neurons withi...

Phrenic plexus

The phrenic plexus (plural: plexuses) is an autonomic nerve plexus and ganglia in the upper abdomen. It is a lateral epiarterial extension of the celiac plexus. Summary location: the bilateral ganglia and plexuses lie along the inferior phrenic arteries origin: preganglionic sympathetic fiber...

Renal plexus

The renal plexus (plural: plexuses) is an autonomic nerve plexus and ganglia located in the upper abdomen and is a lateral perivascular extension of the aorticorenal plexus. Summary location: bilateral plexuses and ganglia lie on the renal arteries lateral to the aorticorenal plexuses origin:...

Aorticorenal plexus

The aorticorenal plexus (plural: plexuses) is an autonomic nerve plexus and ganglia located in the upper abdomen and is an inferior perivascular extension of the larger celiac plexus. Some descriptions separate the aortic and aorticorenal plexuses but they are considerably interconnected and con...

Hepatic plexus

The hepatic plexus (plural: plexuses) is an autonomic nerve plexus and ganglia located in the upper abdomen. Most descriptions are of a periarterial extension of the celiac plexus along the common hepatic artery and portal vein. Summary location: the plexus and ganglia extends to the right fr...

Inferior cervical ganglion

The inferior cervical ganglion (plural: ganglia) is the second largest ganglion of the cervical sympathetic trunk and provides autonomic innervation to the head and neck region. Gross anatomy The inferior cervical ganglion is formed by embryologically fused C7 and C8 sympathetic ganglia. It ha...

Middle cervical ganglion

The middle cervical ganglion (plural: ganglia) is the smallest ganglion of the cervical sympathetic trunk and providing autonomic innervation to the head and neck region. Gross anatomy The middle cervical ganglion is formed by embryologically fused C5 and C6 sympathetic ganglia. It has superio...

Celiac plexus

The celiac plexus (plural: plexuses) is an autonomic nerve plexus and ganglia in the upper abdomen. It is the largest major autonomic plexus. Summary location: the ganglion and plexus lie close to the celiac trunk origin: preganglionic sympathetic fibers via the greater and les...

Ganglion impar

The ganglion impar, also know as the ganglion of Walther, is the midline autonomic ganglion located in the lower pelvis. It is the most distal convergence of the pelvic sympathetic chain which is usually located anterior to the coccyx. It can be found anywhere between the sacrococcygeal joint a...

Pulmonary plexus

The pulmonary plexus is a network of autonomic nerves and ganglia situated at the pulmonary hila of each lung which regulates bronchial smooth muscle tone, submucosal glandular mucous secretion, vascular permeability and blood flow. It is derived from both the sympathetic and parasympathetic ner...

Superior mesenteric plexus

The superior mesenteric plexus is an autonomic nerve plexus and ganglia located in the retroperitoneum. Summary location: the plexus and ganglia lie in the retroperitoneum at the origin of the superior mesenteric artery within the small bowel mesentery origin: formed from branches from ...

Inferior mesenteric plexus

The inferior mesenteric plexus is an autonomic nerve plexus and ganglia located in the retroperitoneum. Summary location: the plexus and ganglia lie in the retroperitoneum at the origin of the inferior mesenteric artery origin: formed mainly from branches from the aorticorenal plexus some c...

Gonads

The gonads (single: gonad) are the paired reproductive organs of humans responsible for the production of gametes and sex hormones. The anatomy of the gonadal arteries differs substantially between the sexes, hence they are covered separately: ovaries in the female located in the pelvis testes...

Autonomic ganglia and plexuses

The autonomic ganglia and plexuses are a collection of ganglia where autonomic preganglionic neurons arising from the CNS synapse with postganglionic neurons outside the CNS, i.e. in the peripheral nervous system. Many of the ganglia contain nerves of the sympathetic and parasympathetic nervous ...

Parasympathetic nervous system

The parasympathetic nervous system (PaNS/PNS), mediated by the head and neck ganglia and pelvic splanchnic nerves, is a major division of the autonomic nervous system. It is composed of general visceral afferent and efferent axons that allow for involuntary control of bodily functions via severa...

Superior alveolar arteries

The superior alveolar arteries is a collective term for the following arteries: posterior superior alveolar artery: branch of the maxillary artery in the pterygopalatine fossa middle superior alveolar artery: small branch of the infraorbital artery anterior superior alveolar artery: branch of...

Uncal artery

The uncal artery is a group of small vessels providing arterial supply predominantly to the uncus. It consists of numerous terminal branches (on average 7 branches per uncus) from major intracranial arteries 1, and it is sometimes subdivided into anterior uncal arteries and posterior uncal, or u...

Carotid arteries

The carotid arteries is used as a collective term for: common carotid artery (CCA) and its two terminal branches external carotid artery (ECA) internal carotid artery (ICA) These arteries provide the vast majority of the arterial supply to the head and neck region and central nervous system...

Suspensory ligaments of the middle ear ossicles

The suspensory ligaments of the middle ear ossicles are ligaments within the middle ear which attach the ossicles to the walls of the mesotympanum 1. The ligaments help the ossicles transmit sound from the tympanic membrane to the oval window. Gross anatomy Origins and insertions of the suspen...

Athelia

Athelia is a rare congenital condition characterized by the absence of the nipple. This may occur unilaterally or bilaterally. Associations Poland syndrome ectodermal dysplasia 2

Track vs tract

The terms track and tract are commonly mixed up in radiology and medicine (and often English more generally). Track Track in medicine refers to an artificially created path through something, a typical example being a "needle track" which is the narrow channel formed when a needle is inserted ...

Nail unit (anatomy)

The nail unit or nail apparatus refers to a group of distal digital structures involved in the function and support of the nail plate. Gross anatomy Structures of the distal phalanx composing the nail unit include 1: nail plate nail matrix nail bed periungual soft tissues eponychium (cuti...

Supraopticohypophyseal tract

The supraopticohypophyseal tract (TA: tractus supraopticohypophysialis) is one of the two major hypothalamohypophyseal neurosecretory tracts connecting the supraoptic nucleus and the paraventricular nucleus in the hypothalamus with the posterior pituitary (neurohypophysis). Gross anatomy Intra...

Anococcygeal raphe

The anococcygeal raphe (plural: anococcygeal raphes or raphae), also known as the anococcygeal ligament or anococcygeal body refers to the midline structure that connects the anorectal junction to the coccyx. It is composed of bilateral interdigitating fibers from the iliococcygeal and pubococcy...

Cerebellomedullary cisterns

Cerebellomedullary cisterns are basal cisterns located laterally and posteriorly around the medulla, between it and the adjacent cerebellum. They are divided into paired lateral cerebellomedullary cisterns (located on either side of the medulla, directly inferior to the cerebellopontine cister...

Accessory muscles of respiration

Accessory muscles of respiration refer to muscles that provide assistance to the main breathing muscles, mainly when additional power is needed, for example during exercise or those with airway pathologies (e.g. COPD) 1,2. During normal quiet breathing, inspiration is an active process primaril...

Scalene muscles

The scalene muscles are a group of three closely related neck muscles. anterior scalene muscles middle scalene muscles posterior scalene muscles Summary origin: transverse processes of mid to lower cervical vertebrae (C2-C7). insertion: first or second ribs. The anterior and middle insert...

Basivertebral nerve

The basivertebral nerve supplies the vertebral endplates and can be a target for treating back pain. Gross anatomy The basivertebral nerve is a paired nerve arising from the sinuvertebral nerve. It ascends from its origin to enter the spinal canal, traversing centrally 1. It courses with the ...

Fibulotalocalcaneal ligament

The fibulotalocalcaneal ligament is part of the deep crural fascia and runs medially from the posteromedial border of the lateral malleolus (anterior malleolar groove) with two sheet-like laminae that insert on the superolateral surface of the calcaneus and the lateral tubercle of the posterior ...

Paraventricular nucleus

The paraventricular nucleus is a group of neurosecretory cells in the hypothalamus that produce the hormones oxytocin and vasopressin (antidiuretic hormone). Gross anatomy The paraventricular nucleus is found in the medial area of the anterior hypothalamus immediately medial to the column of t...

Cardinal ligament

The cardinal ligaments, also known as transverse cervical ligaments or Mackenrodt ligaments, are paired structures that act to support the pelvic organs of the female pelvis. These along with the uterosacral and pubocervical ligaments, provide support to prevent pelvic organ prolapse 1. Gross ...

Oral tori

Oral tori (singular torus) are benign bony outgrowths from the maxilla and mandible: maxillary tori a.k.a. torus palatinus mandibular tori a.k.a. torus mandibularis Oral tori are subcategorised according to their shape 1: flat spindle nodular lobular Although not usually called tori, fur...

Persistent dorsal ophthalmic artery

The persistent dorsal ophthalmic artery is a rare anatomical variant of the ophthalmic artery. Instead of arising from the supraclinoid (C6) segment of the internal carotid artery, as is normally the case, the persistent dorsal ophthalmic artery arises from the lateral aspect of the cavernous (C...

Right gastric vein

The right gastric vein, also known as pyloric vein, forms part of the venous drainage network of the stomach and proximal duodenum. It is a tributary of the portal vein. Gross anatomy Location The right gastric vein courses parallel to the right gastric artery adjacent to the lesser curvature...

Paracingulate sulcus

The paracingulate sulcus is a secondary sulcus running anteroposteriorly in the medial surface of the frontal lobe above and parallel to the cingulate sulcus 1. It is only found in the great apes and only identified in 70-89% of humans 1.

Depressor labii inferioris muscle

The depressor labii inferioris muscle, also known as quadratus labii inferioris muscle, is one of the facial muscles. Summary origin: oblique line of the mandible, medial to the mental foramen insertion: modiolus at the angle of the mouth ascends to medially insert into lower lip innerva...

Scapulothoracic bursa

Scapulothoracic bursae refer to a number of bursae that allow for the gliding movement of the scapulothoracic joint. Two major bursae have been reliably described 1,3: infraserratus (scapulothoracic) bursa: between the serratus anterior muscle and the chest wall supraserratus (subscapularis) ...

Superior cervical ganglion

The superior cervical ganglion (plural: ganglia) is the largest ganglion of the cervical sympathetic trunk, providing autonomic innervation to the head and neck region 1. Gross anatomy The superior cervical ganglion is formed by embryologically fused C1 to C4 sympathetic ganglia. It is elongat...

Ciliary muscle

The ciliary muscle (TA: musculus ciliaris) is located within the ciliary body of the eye. It acts to facilitate lens accommodation for near vision, and receives parasympathetic innervation from short ciliary nerves, arising from the oculomotor nerve via the ciliary ganglion. Gross anatomy The ...

Dilator pupillae muscle

The dilator pupillae muscle is a ring of contractile cells within the iris. These cells are arranged radially, such that their contraction facilitates pupillary dilation (mydriasis). The dilator pupillae muscle receives innervation from the sympathetic nervous system. Gross anatomy The dilator...

Sphincter pupillae muscle

The sphincter pupillae muscle is a circular ring of smooth muscle within the iris responsible for constriction of the pupil (miosis). The structure is stimulated by the parasympathetic nervous system causing the muscle to decrease in diameter as it contracts. Gross anatomy The sphincter pupill...

Pharyngeal muscles

There are multiple pharyngeal muscles that make up the structure of the pharynx. They comprise circular and longitudinal muscles whose overall function is to propel food into the esophagus. Gross anatomy Outer/circular muscles These muscles comprise the outer layer of musculature and act to c...

Persistent primitive olfactory artery

A persistent primitive olfactory artery (PPOA) is a rare variant of the proximal anterior cerebral artery 1,2. It is proposed to be more prone to aneurysms due to its sharp hairpin-like turn. Embryologically, the persistent primitive olfactory artery is the rostral division of the primitive inte...

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