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Choroid plexus

The choroid plexus is located within the cerebral ventricles and is made of epithelial cells, loose connective tissue (tela choroidea) and permeable capillaries. It produces cerebrospinal fluid. Gross anatomy Location roof of the temporal horns of the lateral ventricles, extending along the ...

Chromaffin cells

Chromaffin cells are neuroendocrine cells found predominantly in the medulla of the adrenal gland. They are also found in other ganglia of the sympathetic nervous system and are derived from the embryonic neural crest. Embryology They arise in the fifth week of fetal development when neuroblas...

Ciliary ganglion

The ciliary ganglion is one of four parasympathetic ganglia of the head and neck. It receives parasympathetic fibers from the oculomotor nerve. Gross anatomy smallest of the ganglia (2 mm in size) located posterolaterally in the intraconal space of the orbit (towards the orbital apex) between...

Cingulate gyrus

The cingulate gyrus lies on the medial aspect of the cerebral hemisphere. It forms a major part of the limbic system which has functions in emotion and behavior. The frontal portion is termed the anterior cingulate gyrus (or cortex) 1,2. Gross anatomy Location The cingulate gyrus extends fro...

Cingulate sulcus

The cingulate sulcus is situated directly superior to the cingulate gyrus, which is formed by the medial surface of the frontal lobes that is directly above the corpus callosum.

Circle of Willis

The Circle of Willis is an arterial polygon (heptagon) formed as the internal carotid and vertebral systems anastomose around the optic chiasm and infundibulum of the pituitary stalk in the suprasellar cistern. This communicating pathway allows equalization of blood-flow between the two sides of...

Circular sulcus

The deep circular sulcus surrounds the insular cortex and separates it from the operculum. The circular sulcus is contiguous with the lateral (Sylvian) sulcus.

Circumaortic left renal vein

Circumaortic left renal vein, also known as circumaortic renal collar is an anomaly of left renal vein when a supernumerary or accessory left renal vein passes posterior to the aorta, apart from the normal renal vein passing anterior to the aorta. This anomaly is potentially hazardous, if unreco...

Circumcaval ureter

Circumcaval ureter, also known as retrocaval ureter, is a term used to describe an abnormal course of a ureter that encircles the inferior vena cava. Both of these terms are somewhat misleading, as this configuration is considered a developmental anomaly of the inferior vena cava (IVC). There ar...

Circumduction

Circumduction is the orderly combination of shoulder movements so that the hand traces a circle and the arm traces a cone. In order it is produced by shoulder flexion, abduction, extension and abduction (or the reverse). It is hence produced by co-ordination of all the muscles that produce thes...

Circumflex artery

The circumflex artery (Cx) is one of the two major coronary arteries that arise from the bifurcation of the left main coronary artery (the other branch being the left anterior descending (LAD) artery). Terminology The circumflex artery can be referred to by multiple terms: circumflex artery (...

Circumflex fibular artery

The circumflex fibular artery is a minor artery of the leg. Gross anatomy Origin and course Most often arises from the posterior tibial artery, passes laterally round the neck of the fibula through the soleus to anastomose with the lateral inferior genicular, medial genicular and anterior tib...

Circumventricular organs (CNS)

The circumventricular organs are neuroendocrine anatomical structures localized around the ventricles of the brain. They are characterized by a rich vasculature and fenestrated (permeable) capillaries. As such, with the exception of the subcomissural organ, they are also characterized by the abs...

Cisterna chyli

The cisterna chyli (CC), also known as the receptaculum chyli, is a normal anatomical structure in the lymphatic system. It is seen as a saccular area of dilatation in the lymphatic channels that are located in the retrocrural space, usually to the immediate right of the abdominal aorta. Gross ...

Cisterna magna

The cisterna magna (also known as the cerebellomedullary cistern) is the largest of the CSF-filled subarachnoid cisterns. Gross anatomy The cisterna magna is located between the cerebellum and the dorsal surface of the medulla oblongata at and above the level of the foramen magnum. CSF produce...

Claustrum

The claustrum is a vertical curved sheet of subcortical grey matter oriented sagittally between the white matter tracts of the external capsule and extreme capsule. It is lateral to the putamen and medial to the insular cortex. It is not part of the basal ganglia. There are lateral and medial t...

Clavicle

The clavicle, also colloquially known as the collarbone, is the only bone connecting the pectoral girdle to the axial skeleton and is the only long bone that lies horizontally in human skeleton. Gross anatomy Osteology The clavicle is roughly "S-shaped" with a flattened, concave, lateral one...

Clavipectoral fascia

The clavipectoral fascia is a sheet of loose connective tissue which is the deep layer of fascia in the pectoral region. It acts to suspend the floor of the axilla. Gross anatomy The clavipectoral fascia lies below the clavicular head of the pectoralis major. It fills in the space between the...

Cleft epiphysis

Cleft epiphysis is a normal variant of an epiphysis. It can be either unilateral or bilateral. The most common site is the epiphysis of the first proximal phalanx of the foot. Radiographic features Plain radiograph Plain radiographs will demonstrate a lucent defect in the epiphysis. The borde...

Clitoris

The clitoris (plural: clitorides), the female homologue of the penis, and part of the female reproductive system, is situated at the anterior aspect of the labia minora. The clitoris, like the penis, is formed of a body and glans, formed respectively from the crura of the clitoris and the bulbs ...

Clivus

The clivus (of Blumenbach) is the sloping midline surface of the skull base anterior to the foramen magnum and posterior to the dorsum sellae 1. Specifically, it is formed by the sphenoid body and the basiocciput, which join at the spheno-occipital synchondrosis. At the clivus, the occipital bon...

Cloaca (urogenital)

The cloaca is the terminal portion of the hindgut. It is an embryonic structure (weeks 4-7) in which the distal ends of the gastrointestinal tract and urogenital system share a common channel. The most distal aspect of the cloaca is termed the cloacal membrane. The cloaca, or portions of it, ca...

Cloison sagittale

The cloison sagittale (sagittal partition), also known as Charpy fascia, is a sagittally oriented fascia on either side of the neck that separates the midline deep neck spaces (retropharyngeal space, prevertebral space, and danger space) from the more lateral parapharyngeal space (including caro...

Cloquet's canal

Cloquet's canal, also known as the hyaloid canal or Stilling's canal, is a transparent canal that runs from the optic nerve disc to the lens traversing the vitreous body. It serves as a perivascular sheath surrounding the hyaloid artery in the embryonic eye. History and etymology Hippolyte Clo...

Coalition

A coalition is a joining of two bones that are normally discrete 1. It is usually a congenital abnormality. The bridge between the bones is initially fibrous, then gradually becomes cartilaginous, finally ossifying. Symptoms tend to arise as the coalition forms a synostosis, which is usually fro...

Coccygeus muscle

The coccygeus muscle, also known as the ischiococcygeus muscle, is a remnant muscle of the pelvic floor. Gross anatomy The coccygeus is a paired muscle which is triangular in shape and overlies the sacrospinous ligament. The coccygeus lies parallel to the inferior border of the piriformis musc...

Coccyx

The coccyx (plural: coccyges) is the series of rudimentary vertebrae forming the caudal termination of the vertebral column and is positioned inferior to the apex of the sacrum. The coccyx is one leg of the tripod formed in conjunction with the ischial tuberosities for support in a seated positi...

Cochlea

The cochlea (plural: cochleae) is part of the inner ear osseous labyrinth found in the petrous temporal bone. It contains the cochlear duct, part of the membranous labyrinth which senses hearing. Gross anatomy The cochlea is a shell-shaped spiral that turns between two-and-a-half and two-and-t...

Cochlear aqueduct

The cochlear aqueduct is a small narrow bony canal in the bony labyrinth of the petrous temporal bone. It contains the perilymphatic duct which arises from the scala tympani of the cochlea draining perilymph into the cerebrospinal fluid in the posterior cranial fossa near the lateral margin of t...

Cochlear duct

The cochlear duct (also known as the scala media) is an endolymph-filled cavity located between the scala vestibuli (upper) and the scala tympani (lower) in the cochlea which is part of the inner ear along with the vestibular apparatus 1,4. The cochlea is located in the bony labyrinth, itself fo...

Cochleariform process

The cochleariform process is the thin osseous projection in the anterior wall of the middle ear cavity that acts as the fulcrum for the tendon of the tensor tympani. Gross anatomy Relations The cochleariform process is located 2,3: at the posterior termination of the semicanal for tensor tym...

Cochlear promontory

The cochlear promontory is the name given to the bone that overlies the basal turn of the cochlea protruding into the middle ear cavity. Related pathology glomus tympanicum paragangliomas typically arise in the region of the cochlear promonotory

Celiac artery

Celiac artery, also known as the celiac axis or celiac trunk, is a major visceral artery in the abdominal cavity supplying the foregut. It arises from the abdominal aorta and commonly gives rise to three branches: left gastric artery, splenic artery, and common hepatic artery. Gross anatomy O...

Celiacomesenteric trunk

The celiacomesenteric trunk represents an uncommon vascular anatomical variant where both the celiac trunk and the superior mesenteric artery have a common origin from the abdominal aorta as a single trunk. Its frequency has been reported to occur in about 1.5% of the population 1,2. A celiac-b...

Cog

The cog is a coronally oriented bony process in the middle ear cavity of the temporal bone that projects from the tegmen tympani, separating the anterior epitympanic recess from the posterior epitympanum. The cog ends anterosuperior to the head of the malleus and superior to the cochleariform pr...

Collateral ligaments of the foot

The collateral ligaments of the foot are attached to the dorsal tubercles on the metatarsal heads and the corresponding side of the phalangeal bases.

Collateral sulcus

The collateral sulcus, also known as the medial occipitotemporal sulcus, runs anteroposteriorly on the inferior surface of the temporal lobe and occipital lobe. Anteriorly it is sometimes continuous with the rhinal sulcus 1-3. Anteriorly, it separates the fusiform gyrus laterally, from the par...

Collateral systems between the celiac trunk and superior mesenteric artery

There are several collateral systems between the primary vascular supply of the foregut and midgut. The collateral between the celiac trunk and superior mesenteric artery include: gastroduodenal artery (GDA) branch of the common hepatic artery and anastomoses with branches of the inferior pa...

Colliscalene triangle

The colliscalene triangle is an important anatomical region of the neck, situated medial to the scalenus anterior muscle. It should not be confused with the scalene triangle which is located posterior to the scalenus anterior muscle. Gross anatomy Boundaries medial: lateral border of longus...

Columella

The columella is the most anteroinferior portion of the nasal septum and forms the central fleshy portion between the two nostrils when looking at someone's nose. It is a single midline structure composed of cartilage and overlying skin, extending posteriorly from the tip of the nose. The latera...

Commissural fibers of the brain

Commissural fibers of the brain, also known as commissural tracts of the brain or commissures are a type of white matter tract that cross the midline, connecting the same cortical area in opposite hemispheres (right-left hemispheric connections 3). Commissural fibers include: corpus callosum (...

Common bile duct

The common bile duct (CBD), which is sometimes simply known as the bile duct, is formed by the union of the cystic duct and common hepatic duct (CHD). Terminology On ultrasound imaging, it is not always possible to confidently see where the cystic duct enters the common hepatic duct to form t...

Common carotid artery

The common carotid artery is a paired structure that supplies blood to the head and neck. Summary origin: left: branch of the aortic arch right: branch of the brachiocephalic trunk course: posterior to sternoclavicular joint, lateral to thyroid and trachea supply: head and neck main bran...

Common facial vein

The common facial vein is formed by the joining of the facial vein and anterior branch of the retromandibular vein. It is part of the venous drainage system of the face. Summary origin and termination: the facial vein (along with the facial artery) pierces the deep investing fascia of the neck...

Common femoral artery

The common femoral artery (CFA) is the continuation of the external iliac artery (EIA) at the level of the inguinal ligament. As well as supplying oxygenated blood to the leg, it gives off smaller branches to the anterior abdominal wall and superficial pelvis. Summary origin: continuation of ...

Common femoral vein

The common femoral vein (CFV) forms from the confluence of the femoral vein and the deep femoral vein, and continues as the external iliac vein at the inguinal ligament. It accompanies the common femoral artery. Terminology "Common femoral vein" is not listed in Terminologia Anatomica, however...

Common hepatic artery

The common hepatic artery (CHA) is one of the 3 branches of the celiac artery. Gross anatomy Origin and course The CHA is a terminal branch of the celiac artery. It passes over the top of the pancreas, and downwards to the right in the lesser sac towards the first part of duodenum. It gives o...

Common hepatic duct

The common hepatic duct (CHD) is formed by the junction of the right and left hepatic ducts. It joins the cystic duct to form the common bile duct (CBD). It is approximately 4 cm long and 4 mm in diameter. Together with the cystic duct (laterally) and cystic artery (superiorly), they form Calo...

Common iliac artery

The common iliac arteries (CIAs) are the large paired terminal branches of the abdominal aorta. Gross anatomy Origin The abdominal aorta bifurcates anterolateral (to the left side) of the L4 vertebra, into the right and left common iliac arteries. Course The common iliac arteries (CIAs) en...

Common iliac vein

The common iliac vein, corresponding with the common iliac artery, drains venous blood from the pelvis, lower limbs and their associated structures. Summary location: pelvis, anterior to the sacroiliac joint origin and termination: union of internal and external iliac veins; into the inferior...

Common interosseous artery

The common interosseous artery is a branch of the proximal part of the ulnar artery at the level of the pronator teres in the distal part of the cubital fossa. It is a short vessel that dives laterally and deeply before bifurcating into anterior and posterior interosseous arteries.

Common peroneal nerve

The common peroneal nerve, also known as common fibular nerve, forms the lateral part of the sciatic nerve and supplies the leg. Summary origin: one of two terminal branches of the sciatic nerve course: diverges laterally to enter the lateral compartment of the leg terminal branches deep pe...

Compressor naris muscle

Compressor naris muscle forms the transverse component of nasalis muscle, and is one of the muscles of the nose, a subset of the muscles of facial expression. Summary origin: frontal process of maxilla insertion: medial insertion into a transverse aponeurosis innervation: facial nerve (V...

Concha bullosa

Concha bullosa (plural: conchae bullosae) (also known as middle turbinate pneumatization) is a common finding and although associated with deviation of the nasal septum, it is usually of little clinical importance. Epidemiology Concha bullosa is a normal variant and is one of the most common v...

Condylar canal

The condylar canal, or canalis condylaris, is a skull base canal in the posterior cranial fossa, located in the condylar fossa. It is the largest of the emissary foramina of the skull 1. Summary location: in the condylar fossa of the posterior cranial fossa, posterior to the occipital condyles...

Condylar emissary veins

The condylar emissary veins (anterior, lateral, posterior) are major posterior cranial fossa emissary veins: anterior condylar vein connects the internal vertebral venous plexus to the internal jugular vein lateral and posterior condylar veins connect the external vertebral venous system with ...

Condyloid joint

Condyloid joints are a type of synovial joint where the articular surface of one bone has an ovoid convexity sitting within an ellipsoidal cavity of the other bone. Movements Condyloid joints allow movement with two degrees of freedom much like saddle joints. They allow flexion/extension, ab...

Confluence of sinuses

The confluence of sinuses, also known as the torcula or torcular herophili is the site of the confluence of: superior sagittal sinus straight sinus occipital sinus transverse sinuses The anatomy is highly variable and three types can be distinguished: type 1: superior sagittal sinus drains...

Congenital absence of a spine pedicle

Congenital absence of a spine pedicle is a rare congenital condition, but awareness of its characteristic imaging appearance is important to avoid misdiagnosis. Failure to recognize this entity can lead to misdiagnosis of unilateral facet subluxation/dislocation, leading to unnecessary treatmen...

Congenital absence of the internal carotid artery

Congenital absence of the internal carotid artery (ICA) is a rare anomaly that occurs in less than 0.01% of the population. It encompasses agenesis, aplasia, and hypoplasia 1. The most common type of collateral flow is through the circle of Willis, through the anterior communicating artery (ACO...

Congenital anomalies of the posterior atlas arch

Congenital anomalies of the posterior arch of the atlas (C1) are relatively common anomalies. They may range from partial defects presenting as clefts to complete absence of the posterior arch (aplasia). These anomalies are classified according to Currarino (see below). It should not be confuse...

Congenital coronary artery anomalies

Congenital coronary artery anomalies (CCAAs) are not common, found only in ~1% (range 0.1-2%) of patients 1,3.The most important finding to look for is the "malignant" course of anomalous coronary artery, i.e. does the artery run between big pulsating objects - right ventricular outflow tract / ...

Congenital intrahepatic portosystemic shunt classification

This congenital intrahepatic portosystemic shunt classification was proposed by Park et al. in 1990 1: type 1: single large vessel of constant diameter connecting the right portal vein to the inferior vena cava type 2: localized, peripheral shunt with one or more communications in a single hep...

Congenital portosystemic shunt

Congenital portosystemic shunts are rare, extrahepatic or intrahepatic, anatomical abnormalities shunting blood from the portal venous system to the systemic venous system and, thus, avoiding passage through the hepatic acinus. Terminology The term “portosystemic shunt” can be used to refer t...

Congenital pulmonary venolobar syndrome

Congenital pulmonary venolobar syndrome is a condition comprising a rare group of cardiac and pulmonary congenital abnormalities occurring variably in combination. The abnormalities include: anomalous pulmonary venous drainage particularly scimitar syndrome with hypogenetic right lung pulmona...

Congenital urachal anomalies

Congenital urachal anomalies are a spectrum of potential anomalies that can occur due to incomplete involution of the urachus. Epidemiology A urachal remnant occurs in approximately 1 in 5000 patients. Pathology The urachus connects the dome of the bladder to the umbilical cord during fetal ...

Congenital utero-vaginal anomalies

There are many classification systems for congenital utero-vaginal anomalies. These include: Buttram and Gibbons classification 2 American Fertility Society (AFS) classification Modified Rock and Adam - AFS classification Modified Rock and Adam - AFS classification This classification divid...

Conjoined nerve root

A conjoined root is a type of developmental anomaly involving a nerve root. It is the most common nerve root developmental anomaly of the cauda equina being twice as common as two roots in the same foramen, the next most common anomaly. Epidemiology The incidence in cadaveric studies is ~10 (r...

Conjoint tendon

The conjoint tendon forms when the medial fibers of the internal oblique aponeurosis unite with the deeper fibers of the transversus abdominis aponeurosis. The conjoint tendon then turns inferiorly and attaches onto the pubic crest and pecten pubis 1. It forms part of the posterior wall of the i...

Conjunctiva

The conjunctiva (plural: conjunctivas or conjunctivae) is a transparent membrane is attached at the margins of the cornea. It is loosely attached to the sclera and thence reflected over the inner surface of the eyelids. It is firmly attached to the tarsal plates and blends with the skin at the m...

Conoid ligament

The conoid ligament is one of two components forming the coracoclavicular (CC) ligament. The trapezoid ligament is the other component. Gross anatomy The conoid ligament takes the shape of an inverted cone. It is the posteromedial part of the coracoclavicular ligament. Its apex originates from...

Conoid tubercle

The conoid tubercle also known as the coracoid tuberosity (not to be confused with the coracoid process of the scapula) is a bony prominence on the inferior surface of the lateral third of the clavicle. It marks the insertion of the conoid ligament (which along with the trapezoid ligament) for...

Contents of the cubital fossa (mnemonic)

A useful mnemonic to remember the contents of the cubital fossa is, from medial to lateral: My Brother Throws Rad Parties Mnemonic M: median nerve B: brachial artery T: tendon of biceps R: radial nerve P: posterior interosseous branch of radial nerve

Conus artery

The conus artery is a small early branch off the right coronary artery (RCA) circulation. Gross anatomy Supply The artery has a variable distribution, but usually supplies a region of the anterior interventricular septum and the conus of the main pulmonary artery (hence its name). Variant an...

Conus medullaris

The conus medullaris is the terminal end of the spinal cord. Gross anatomy After the cord terminates, the nerve roots descend within the spinal canal as individual rootlets, collectively termed the cauda equina. The conus medullaris most commonly terminates at the L1/2 intervertebral disc leve...

Cooper ligament

Cooper ligaments are the fibrous connections between the inner side of the breast skin and the pectoral muscles. Working in conjunction with the fatty tissues and the more fibrous lobular tissues, they are largely responsible for maintaining the shape and configuration of the breast. They play a...

Coracoacromial ligament

The coracoacromial ligament is a flat triangular band that plays a supportive role for the shoulder joint. Gross anatomy originates from the medial border of the acromion attaches to the lateral border of the coracoid process overlies the subacromial bursa indirectly supports the head of th...

Coracobrachialis muscle

The coracobrachialis muscle is one of the three muscles of the anterior compartment of the arm. It sits beneath the biceps brachii, inserting via a flat tendon into the medial shaft of the humerus. origin: coracoid process of scapula insertion: via a flat tendon onto the midportion of the medi...

Coracoclavicular joint

The coracoclavicular joint is a normal variant of the pectoral girdle, where the conoid tubercle of the clavicle appears enlarged or elongated, with a flattened inferior surface where it approximates the coracoid process of the scapula to form an articulation. Epidemiology More common in Asia...

Coracoclavicular ligament

The coracoclavicular (CC) ligament is the major vertical stabilizing factor of the acromioclavicular joint. Gross anatomy The coracoclavicular ligament can be divided into two parts, the more medial conoid ligament and trapezoid ligament. conoid ligament origin: knuckle of the coracoid proc...

Coracohumeral ligament

The coracohumeral ligament (CHL) is a strong supportive ligament of the shoulder joint and is a part of rotator cuff interval. Gross anatomy originates from the lateral surface of the base of the coracoid process runs laterally across the glenohumeral capsule and covers the long head of bicep...

Coracoid process

The coracoid process is an anteriorly projecting hook-like process on the superolateral edge of the scapula that projects anterolaterally. Gross anatomy Attachments muscles: coracobrachialis from the medial apex short head of biceps brachii from the lateral apex pectoralis minor from the m...

Cornea

The cornea forms the fibrous layer of the anterior portion of the eye. It functions to refract light entering the eye. Summary location: anterior one-sixth of the eyeball blood supply: avascular innervation: long ciliary nerves relations: continuous with the sclera posteriorly and covered...

Corniculate cartilage

The corniculate cartilages are paired, elastic and accessory cartilages of the larynx that lie superior to and articulate with the apices of the arytenoid cartilages. They are components of the laryngeal cartilages. The word 'corniculate' comes from the latin word 'cornu' meaning horn-like.

Coronal suture

The coronal suture is the cranial suture formed between the two parietal bones and the frontal bone. At the junction of coronal, sagittal and frontal sutures is the anterior fontanelle which is open at birth and usually fuses at around 18-24 months after birth. Fusion of the coronal suture occu...

Corona mortis

Corona mortis, Latin for "crown of death", is a common variant vascular anastomosis between the external iliac artery or deep inferior epigastric artery with the obturator artery. It is reported to be present in a third of patients on routine multi-detector CT examination 1,4. Knowledge of thi...

Corona radiata

The corona radiata refer to a pair of white matter tracts seen at the level of the lateral ventricles. Superiorly they are continuous with the centrum semiovale. Inferiorly these tracts converge as the internal capsule.

Coronary arterial dominance

Coronary arterial dominance is defined by the vessel which gives rise to the posterior descending artery (PDA), which supplies the myocardium of the inferior 1/3rd of the interventricular septum. Most hearts (80-85%) are right dominant where the PDA is supplied by the RCA. The remaining 15-20% ...

Coronary arteries

The coronary arteries arise from the coronary sinuses immediately distal (superior) to the aortic valve and supply the myocardium with oxygenated blood. They branch and encircle the heart to cover its surface with a lacy network, perhaps resembling a slightly crooked crown. Gross anatomy The t...

Coronary sinus

The coronary sinus is the largest cardiac venous structure. It returns the majority of the blood supply for the left ventricle to the right atrium. Gross anatomy The coronary sinus courses along the posterior wall of the left atrium into the left atrioventricular groove. It normally drains int...

Coronary veins

The coronary veins return deoxygenated blood from the myocardium back to the right atrium. Most venous blood returns via the coronary sinus. Coronary venous anatomy is highly variable, but is generally comprised of three groups: cardiac veins which drain into the coronary sinus: great cardiac ...

Coronoid process (disambiguation)

Coronoid process can refer to a number of different anatomical structures: coronoid process (mandible) coronoid process (ulna)

Corpora quadrigemina

The corpora quadrigemina (Latin for "quadruplet bodies", singular: corpus quadrigeminum) are the four colliculi, two inferior and two superior, that sit on the quadrigeminal plate on the posterior surface of the midbrain. The corpora quadrigemina are reflex centers involving vision and hearing:...

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