Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

2,851 results found
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Digastric muscle

The digastric muscle is composed of two bellies, anterior and posterior, connected by an intermediate round tendon. The two bellies of the muscle have different embryonic origins and hence are supplied by different cranial nerves. Summary origin anterior belly: digastric fossa on the deep sur...
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Digastric triangle

The digastric triangle is one of the paired triangles in the anterior triangle of the neck. The triangles of the neck are surgically focused, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spaces of ...
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Dilator naris muscle

Dilator naris muscle forms the alar component of nasalis muscle, and is one of the muscles of the nose, a subset of the muscles of facial expression.  Summary origin: maxilla​​ insertion: ​nasal ala innervation: facial nerve (VII) action: flaring of the nostril Gross anatomy Origin fiber...
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Discoid meniscus

Discoid menisci are those that have a body that is too wide, usually affecting the lateral meniscus. They are incidentally found in 3-5% of knee MRI examinations.  Epidemiology Discoid menisci are congenital, frequently bilateral (up to 50%) and have been reported in twins, although no genetic...
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Distal dural ring

The distal dural ring is an anatomical landmark that separates the extradural from the intradural intracranial internal carotid artery (ICA). It is located at the junction of the cavernous, clinoid and ophthalmic segments of the ICA. Gross anatomy Anatomy of this region is complex and varied a...
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Distal radioulnar joint

The distal radioulnar joint is a pivot type synovial joint between the distal radius and ulna. Summary articulation: pivot type synovial joint between the distal aspect of the radius and the ulna movement: rotation of the distal radius ligaments: triangular ligament, and anterior and posteri...
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Distal tibiofibular syndesmosis

The tibiofibular syndesmosis is a complex fibrous joint composed of multiple ligaments and a broad fibrous interosseous membrane that spans between the tibia and fibula throughout the length of both bones. The distal osseous part of this syndesmotic joint includes the following four components:...
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Dominant ovarian follicle

A dominant ovarian follicle refers to the follicle that enlarges to release an ovum during a menstural cycle. Usually approximately 10 Graafian follicles begin to mature where one becomes a dominant follicle and the rest become atretic ovarian follicles. After release of the ovum the remainder o...
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Dorello canal

Dorello canal channels the abducens nerve (CN VI) from the pontine cistern to the cavernous sinus.  Gross anatomy Dorello canal is found at the medial most end of the petrous ridge at the confluence of the inferior petrosal, basal, and cavernous sinuses. Boundaries superiorly: petrosphenoida...
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Dorsal columns

The dorsal columns, or posterior columns, are ascending pathways primarily concerned with sensory function. They are responsible for transmitting vibration, conscious proprioception, and fine (discriminative) touch 1,2. The dorsal columns are divided two tracts, which are discussed separately 2...
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Dorsal defect of the patella

Dorsal defects of the patella are benign subchondral lesions of unknown etiology and a normal developmental anomaly of the patella, which can be mistaken for a pathological process such as a focus of infection or osteochondritis dissecans. Epidemiology Dorsal defect of patella occurs in males ...
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Dorsal horn

The dorsal horn of the spinal cord is one of the grey longitudinal columns found within the spinal cord. It primarily acts as the termination of primary afferent fibers via the dorsal roots of the spinal nerves. Gross Anatomy On transverse section of the spinal cord the spinal grey matter is d...
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Dorsal intercarpal ligament

The dorsal intercarpal ligament is one of the extrinsic wrist ligaments. Gross anatomy The dorsal intercarpal ligament has a horizontal orientation, however, together with the dorsal radiotriquetral ligament, it is said to have a zig-zag configuration. It runs from the dorsal tubercle of the ...
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Dorsal interossei (foot)

The four dorsal interossei muscles are the most superior muscles in the sole of the foot and abduct the second to fourth toes relative to the long axis through the second toe. Summary origin sides of metatarsals of toes I to V insertion extensor hoods and bases of proximal phalanges of toes...
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Dorsal interossei muscles (hand)

The interossei muscles form part of the intrinsic muscles of the hand, and as a group consist of four palmar (1st is often rudimentary) and four dorsal muscles. Collectively, the interossei contribute to abduction and adduction of the fingers and also contribute to flexion of the metacarpophala...
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Dorsal nasal artery

The dorsal nasal artery, also known as the dorsonasal artery, is a terminal branch of the ophthalmic artery. Gross anatomy Arising as a terminal branch of the ophthalmic artery, the dorsal nasal artery exits the orbit after piercing the orbital septum above the medial canthal tendon (medial pa...
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Dorsal nerve of penis or clitoris

Dorsal nerve of penis or clitoris is one of the two terminal branches of the pudendal nerve that arises from nerve whilst in the pudendal canal. The other terminal branch is the perineal nerve.  Gross anatomy Course Entering the urogenital triangle of the perineum, the dorsal nerve of penis o...
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Dorsal pancreatic artery

The dorsal pancreatic artery is a branch of the splenic artery that supplies the pancreas. It arises from the proximal splenic artery and descends a short distance to run along the posterior margin of the pancreas where it divides in to left and right branches. the right branches pass either an...
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Dorsal radioulnar ligament

The dorsal radioulnar ligament is one of the primary stabilizers of the distal radioulnar joint and forms part of the triangular fibrocartilage complex 1,2. Summary location: extending from posterior margin of the ulnar notch at the distal radius to the posterior portion of the head of the uln...
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Dorsal root ganglion

The dorsal root ganglia are an enlargement of the dorsal root of spinal nerves representing the cell bodies of the primary somatosensory neurons. Gross anatomy Each dorsal root ganglion is oval and proportional in size to its related root. They are usually found just distal to the intervertebr...
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Dorsal scapular artery

The dorsal scapular artery is a branch of either the transverse cervical artery (from the thyrocervical trunk off the first part of the subclavian artery) or an independent branch from the third (or less commonly second) part of the subclavian artery. It accompanies the dorsal scapular nerve, c...
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Dorsal scapular nerve

The dorsal scapular nerve is a branch from the C5 root of the brachial plexus and supplies the rhomboid muscles. Gross anatomy Origin Posterior aspect of the C5 root of the brachial plexus. Course It courses through scalenus medius then accompanies the dorsal scapular vessels inferiorly, de...
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Dorsum sellae

The dorsum sellae is the square shaped process of the sphenoid bone. It ascends superiorly from the posterior part of the sphenoid body to form the posterior wall of the sella turcica. Gross anatomy Relations The dorsum sellae forms the posterior wall of the sella turcica, which houses the pi...
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Double aortic arch

Double aortic arches are the most common symptomatic type of the aortic arch variant. It may account for up to 50-60% of vascular rings. Clinical presentation Double aortic arch is mostly diagnosed in childhood due to symptoms related to esophageal and/or tracheal obstruction. Respiratory symp...
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Double retroaortic left renal vein

Double retroaortic left renal vein is a very rare entity that is usually clinically silent and detected incidentally at imaging, surgery, or autopsy. The knowledge of anatomical variations helps the surgeon or interventionist to avoid complications during surgery and interventional procedures 4...
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Dromedary hump

Dromedary humps are prominent focal bulges on the lateral border of the left kidney. They are normal variants of the renal contour, caused by the splenic impression onto the superolateral left kidney. Dromedary humps are important because they may mimic a renal mass, and as such is considered a...
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Duct of Rivinus

The duct of Rivinus connects the sublingual gland to the floor of the mouth. Despite its name, it is not a single duct, but numerous small ducts all of which open into the floor of the mouth and are collectively termed the duct of Rivinus. The largest of these little ductules is the major duct...
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Ducts of the salivary glands

The ducts of the salivary glands allow the passage of salivary juice from the glands to the oral cavity: parotid duct (Stenson duct): connects the parotid gland to the buccal mucosa, adjacent to maxillary second molar submandibular duct (Wharton duct): connects the submandibular gland to the f...
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Ductus arteriosus

The ductus arteriosum (DA) (or arteriosus) is the thick short conduit for blood to bypass the non-ventilated lungs in the fetus. It is located between and connects the proximal left pulmonary artery and the undersurface of the aortic arch distal to the origin of the last branch of the arch, at t...
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Ductus deferens

The ductus deferens (plural: ductus deferentes) forms part of the male internal genitalia where it transports sperm from the epididymis to the ejaculatory duct. In modern anatomic nomenclature, it is no longer referred to as the vas deferens (plural: vasa deferentia). Gross anatomy The ductus ...
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Ductus diverticulum

Aortic ductus diverticulum is a developmental outpouching of the thoracic aorta which may be mistaken for an acute aortic injury. Gross anatomy It is usually seen at the anteromedial aspect of the aorta at site of the aortic isthmus, where the ligamentum arteriosum attaches. It is also the sit...
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Ductus venosus

Ductus venosus (DV) is a narrow, trumpet-shaped vessel which is seen in the fetal liver connecting the umbilical vein directly to the caudal inferior vena cava. The vessel plays a critical role in the fetal circulation by shunting oxygenated and nutrient-rich umbilical venous blood from the plac...
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Duodenojejunal flexure

The duodenojejunal (DJ) flexure or junction is the anatomical border between the duodenum and the jejunum. Gross anatomy The DJ flexure is located anterolateral to the aorta at the level of the upper border of the second lumbar vertebra. It makes a sharp turn anteroinferiorly to become the jej...
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Duodenum

The duodenum is the first part of the small intestine and is the continuation of the stomach. Gross anatomy The duodenum is a 20-30 cm C-shaped hollow viscus predominantly on the right hand side of the vertebral column. It lies at the level of L1-3 and the convexity of the duodenum (called the...
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Duplex appendix

Duplex appendix is a rare anomaly of the appendix and is usually discovered incidentally during surgery for appendicitis. Epidemiology Duplication of the vermiform appendix is extremely rare. It is found in only 1 in 25,000 patients (incidence ~0.004%) operated on for acute appendicitis. Altho...
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Duplicated middle cerebral artery

The duplicated middle cerebral artery is an anatomical variant in which there are two middle cerebral arteries originating from the distal end of the internal carotid artery. Supply The duplicated artery supplies the anterior temporal lobe. Differential diagnosis It should not be confused wi...
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Duplication of inferior vena cava

Duplication of the inferior vena cava is a relatively rare vascular anomaly, but this caval abnormality needs to be recognized, especially in association with renal anomalies like crossed fused ectopia or circumaortic renal collar 1,2. Epidemiology The incidence of inferior vena cava duplicati...
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Dural venous sinuses

Dural venous sinuses are venous channels located intracranially between the two layers of the dura mater (endosteal layer and meningeal layer). They can be conceptualised as trapped epidural veins. Unlike other veins in the body, they run alone, not parallel to arteries. Furthermore, they are va...
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Dura mater

The dura mater, also known as the pachymeninx (plural: pachymeninges), is the tough outer layer of the meninges that surrounds the central nervous system and is pierced by the cranial nerves, the internal carotid arteries and the vertebral arteries.  Intracranially, it is formed by two layers: ...
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Ear

The ear refers to the entire vestibulocochlear organ and is divided anatomically into: external ear middle ear inner ear
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Ectopic intracaval liver

Ectopic intracaval liver is a very rare congenital abnormality of the liver in which a part of the liver, not contiguous with the liver proper, lies within the inferior vena cava (IVC).  Ectopic hepatic lobes elsewhere have been described rarely as congenital abnormalities, but a location withi...
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Ectopic kidney

An ectopic kidney, also known as renal ectopia, is a congenital renal anomaly characterized by the abnormal location of one or both of the kidneys. They can occur in several forms: cross fused renal ectopia ectopic thoracic kidney pelvic kidney Epidemiology The estimated incidence of an ec...
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Ectopic pancreatic tissue

Ectopic pancreatic tissue, also known as heterotopic pancreatic tissue, refers to the presence of pancreatic tissue in the submucosal, muscularis or subserosal layers of the luminal gastrointestinal tract outside the normal confines of the pancreas and lacking any anatomic or vascular connection...
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Ectopic posterior pituitary

An ectopic posterior pituitary reflects a disruption of normal embryogenesis of the posterior pituitary and is one of the more common causes of pituitary dwarfism. Although it can be an isolated abnormality, numerous other congenital central nervous system malformations have been identified. Whe...
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Ectopic thyroid

An ectopic thyroid gland is one which is located in a location other than the normal position anterior to the laryngeal cartilages. Variant anatomy During embryological development, the thyroid gland migrates down from the foramen cecum at the posterior aspect of the tongue to its permanent lo...
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Ejaculatory duct

The ejaculatory ducts are paired structures of the male reproductive system and convey seminal fluid. Gross anatomy Each ejaculatory duct is formed by the union of the excretory duct of the seminal vesicle and the ampulla of the ductus deferens, and is approximately 2 cm long. The ducts course...
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Ejaculatory pathway of sperm (mnemonic)

A useful mnemonic to remember the ejaculatory pathway of sperm is: SEVEN UP Mnemonic S: seminiferous tubules of the testes E: epididymis V: vas (ductus) deferens E: ejaculatory duct N: nothing U: urethra P: penis
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Elbow

The elbow is a complex synovial joint formed by the articulations of the humerus, the radius, and the ulna.  Gross anatomy Articulations The elbow joint is made up of three articulations 2,3: radiohumeral: capitellum of the humerus with the radial head ulnohumeral: trochlea of the humerus w...
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Elbow bursae

The elbow bursae are a collection of synovial-lined bursae that exist around the elbow.  They can be divided into bursae around the olecranon and in the cubital fossa. Olecranon bursae superficial olecranon bursa: lies between the olecranon and the subcutaneous tissue. subtendinous olecranon ...
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Elbow ossification

Elbow ossification occurs at the six elbow ossification centers in a reproducible order. Being familiar with the order of ossification of the elbow is important in not mistaking an epicodylar fracture for a normal ossification center.  Appearance Order The order of appearances of the elbow os...
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Eleventh rib

The atypical 11th rib is one of two floating ribs. Gross anatomy Osteology The 11th rib has a single facet on its head for articulation with the T11 vertebra. It has a short neck and no tubercle. The angle is slight. Its costal groove is shallow. The internal surface of this rib faces slightl...
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Elster's rule (pituitary gland)

Elster's rule provides a guide to the expected approximate pituitary gland's height in relation to age 1. The rule follows an even-numbered pattern of 6, 8, 10, and 12 1: 6 mm pituitary gland height in infants and children 8 mm pituitary gland height in men and postmenopausal women 10 mm pitu...
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Emissary veins

Emissary veins (also known as the vena emissaria) are small valveless, thin-walled veins that pass via the foramina of the skull, providing a venous communication between the dural venous sinuses and veins of the scalp or veins inferior to the skull base (cranial-cerebral anastomosis). Thus, the...
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Empty sella

An empty sella, also known as an empty pituitary fossa, is a relatively common incidental finding and posed more of a diagnostic problem before modern cross-sectional imaging. In addition to being incidental, a well-established association with benign intracranial hypertension is also recognized...
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Endochondral ossification

Endochondral ossification describes the process of ossification from mesenchymal cells (stem cells) with a cartilaginous template and is involved in the healing process of fractures. Bone formation occurs at centers of ossification (or ossification centers) which are either primary or secondary...
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Endolymph

Endolymph is one of the two types of cochlear fluids, the other being perilymph. It is located in the scala media of the cochlea. It is secreted by the stria vascularis (also colloquially called the 'battery of the cochlea') on the outer wall of the scala media. It has a high level of potassium...
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Endolymphatic duct

The endolymphatic duct is a small epithelial-lined channel, part of the membranous labyrinth that passes through the vestibular aqueduct in the bony labyrinth of the petrous temporal bone. It arises from the utricle and saccule via the utriculosaccule duct and drains endolymph. The distal end is...
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Endometrium

The endometrium refers to the inner lining of the uterine lumen, composed of endometrial glands surrounded by loose highly cellular connective tissue. Gross anatomy Layers In women of reproductive age, the endometrium is composed of two layers: stratum basale (basal layer): describes the de...
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Enthesis

An enthesis (plural: entheses), also known as a footprint, generally refers to the anatomic junction where connective tissue (e.g. ligaments, tendons, joint capsules) attach to bone. Enthesis are commonly classified into two types 1: fibrous fibrocartilage Histology Fibrous In a fibrous en...
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Entorhinal cortex

The entorhinal cortex (Brodmann area 28) is located in the mesial temporal lobe and acts as the interface between the hippocampus and the neocortex. It has been considered part of the hippocampal formation (along with Ammon’s horn, subiculum and presubiculum), but is difficult to precisely local...
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Eparterial bronchus

The eparterial bronchus is a synonymous term for the right superior lobar bronchus. Its name is derived from the bronchus being the only one originating superior to the level of the pulmonary artery. Conversely, all other bronchi can be referred to by their anatomical relationship to the pulmona...
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Ependymal cells

Ependymal cells are one of the four main types of glial cells, and themselves encompass three types of cells 1:  ependymocytes: line the ventricles of the brain and central canal of the spinal cord tanycytes: line the floor of the third ventricle overlying the median eminence of the hypothalam...
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Ependymocytes

Ependymocytes are one of the three types of ependymal cells, which in turn are one of the four principles types of glial cells, and are found lining the ventricular system of the brain and the central canal of the spinal cord 1.  They do not form a water-tight barrier between the cerebrospinal ...
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Epididymal appendix

Epididymal appendices, also known as appendix of the epididymis or appendix epididymis, are an testicular appendage found at the head of the epididymis 1. They represent a developmental remnant of the mesonephric duct (Wolffian duct). In 78% of the cases, it has a stalk configuration and is thus...
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Epididymis

The epididymis (plural: epididymides) is situated adjacent to the testis within the scrotal sac. Its primary function is the collection, maturation and transport of sperm via the ductus deferens. Gross anatomy The epididymis is an elongated structure, posterolateral to the testis. It can be su...
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Epidural ligaments

The epidural ligaments, also known as meningovertebral ligaments, are variably thick bands of connective tissue located within the spinal epidural space attaching the outer surface of the theca to the inner borders of the spinal canal (vertebrae and ligaments).  They are somewhat variable in nu...
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Epiglottis

The epiglottis is a single midline leaf-shaped fibrocartilaginous structure that forms part of the supraglottic larynx and defines the division of the hypopharynx from the larynx.  Gross anatomy The epiglottis projects posterosuperiorly from its stem-like base, which is attached to the thyroid...
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Epiphysis

The epiphyses (singular: epiphysis) are the rounded portions at the ends of a bone separated from the metaphysis by the physis. The epiphysis contributes to a joint, compared with an apophysis which is a site of tendon or ligament attachment. Once the growth plate has fused, the epiphysis and me...
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Epiploic appendage

Epiploic appendages (or appendix epiploica, plural: appendices epiploicae) are peritoneum-lined protrusions of subserosal fat that arise from the surface of the large bowel.  Gross anatomy Epiploic appendages typically measure 1.5 x 3.5 cm but have been reported to measure up to 15 cm in lengt...
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Epiploic foramen

The epiploic foramen (also called the foramen of Winslow) is a passage between the greater (general peritoneal space) and lesser sac (omental bursa), allowing communication between these two spaces. Gross anatomy Boundaries It has the following borders: anterior: the free edge of the lesser ...
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Episternal ossicles

Episternal (or suprasternal) ossicles are accessory bones and a normal variant of the sternum. They result from supernumerary ossification centers and are seen in ~4% (range 1-7%) of the population. Gross anatomy Episternal ossicles are usually located posterior or superior to the superior bor...
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Epithalamus

The epithalamus is a dorsal posterior segment of the diencephalon that includes the habenula, stria medullaris, pineal gland, and posterior commissure. Its function is the connection between the limbic system to other parts of the brain.
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Epitransverse process of the atlas

Epitransverse process is a rare anatomical variant of the atlas, consisting of a bony exostosis which extends cephalad from the transverse process of the atlas to articulate with the occipital bone. This process sometimes meets with a paracondylar process from the occipital bone, forming a pseud...
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Epitympanum

The epitympanum, also known as the attic or epitympanic recess, is the most superior portion of the tympanic cavity. It is that portion of the tympanic cavity superior to the axial plane between the tip of the scutum and the tympanic segment of the facial nerve 1,3. Posteriorly the epitympanum ...
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Erector spinae group

The erector spinae group is the intermediate layer of the intrinsic muscles of the back. This group is made of three subgroups, with the group divisions occurring by location. iliocostalis subgroup is the most lateral longissimus subgroup is between iliocostalis and spinalis spinalis subgroup...
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Erector spinae muscles (mnemonic)

There are multiple handy mnemonics to recall the erector spinae muscles. They usually describe the position from lateral to medial.  I Like Standing I Love Sex I Long for Spinach I Like Siri Mnemonic I: iliocostalis L: longissimus S: spinalis
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Esophageal lymph node stations

Esophageal lymph node stations are those nodal stations in the neck, chest, and abdomen considered regional (rather than distant) for the purpose of esophageal cancer staging. This list reflects the map provided in the 8th edition of the American Joint Committee on Cancer (AJCC) Cancer Staging M...
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Ethmoidal air cells

The ethmoidal air cells, also known less commonly as the ethmoidal sinuses, form one of the four pairs of paranasal sinuses. They are located within the single, midline ethmoid bone. Summary location: between the orbit and the nasal cavity, within the ethmoid labyrinth of the ethmoid bone blo...
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Ethmoid bone

The ethmoid bone is a single midline facial bone that separates the nasal cavity from the brain and is located at the roof of the nose and between the orbits. It is a cubical shape and is relatively lightweight because of its spongy construction. It contributes to the anterior cranial fossa. Gr...
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Ethmoid bulla

The ethmoid bulla, also known as bulla ethmoidalis, is the largest and most consistent air cell of the anterior ethmoid air cells. Gross anatomy It is located posterior to the frontal recess and enclosed laterally by the lamina papyracea. It forms the roof of the middle meatus. It can be clas...
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Ethmoid infundibulum

The ethmoid infundibulum is a curved cleft of the ethmoid bone which leads into the anterior portion of the hiatus semilunaris. It is bordered medially by the uncinate process and laterally by the orbital plate of the ethmoid. The infundibulum is often continuous with the frontal recess into whi...
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Eustachian tube

The Eustachian tube, also known as the pharyngotympanic tube or auditory tube, is the channel via which the tympanic cavity communicates with the nasopharynx. It is ~36 mm in length and is directed downward, forward, and medially, forming an angle of about 45 degrees with the sagittal plane and ...
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Eustachian valve

The eustachian valve (also known as the "valve of the inferior vena cava") is a ridge of variable thickness in the inferior right atrium. It is a remnant of a fetal structure that directed incoming oxygenated blood to the foramen ovale and away from the right atrium.   Incomplete regression of ...
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Extensor carpi radialis brevis muscle

Extensor carpis radialis brevis (ECRB) is a muscle of superficial layer on posterior compartment of the forearm. It passes through the 2nd extensor compartment of the wrist. ECRB is one of the three muscles forming the mobile wad of Henry. It is one of the extrinsic muscles of the hand. Summary...
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Extensor carpi radialis longus muscle

Extensor carpis radialis longus (ECRL) is a muscle of the superficial layer in the posterior compartment of the forearm. It passes through the 2nd extensor compartment of the wrist. It is one of the three muscles forming the mobile wad of Henry. It is one of the extrinsic muscles of the hand. S...
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Extensor carpi ulnaris

Extensor carpi ulnaris (ECU) is a muscle of the superficial layer of the posterior compartment of the forearm. It is separated from the extensor digitorum and the extensor digiti minimi muscles by a distinct intermuscular septum. It is the only forearm extensor that lies in its own fibro-osseous...
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Extensor compartments of the wrist

The extensor tendons at the level of the wrist are divided into six extensor compartments that are designated by Roman numerals from lateral to medial 1: I: extensor pollicis brevis, abductor pollicis longus II: extensor carpi radialis longus, extensor carpi radialis brevis III: extensor poll...
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Extensor digiti minimi

Extensor digiti minimi (EDM) is a muscle of the superficial layer of the posterior compartment of the forearm, and with other extensor muscles arises from a common extensor tendon attached to the lateral epicondyle of the humerus. The EDM represents a medial group of superficial extensor muscles...
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Extensor digitorum

Extensor digitorum (ED), also known as extensor digitorum communis (EDC), is a muscle of the superficial layer of the posterior compartment of the forearm and with other extensor muscles arises from a common tendon attached to the lateral epicondyle of the humerus. It is one of the extrinsic mus...
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Extensor digitorum brevis manus muscle

The extensor digitorum brevis manus (EDBM) muscle is an accessory muscle in the hand and is a normal anatomical variant.  Summary origin: distal radius and posterior radiocarpal ligament insertion: extensor hood of 2nd or 3rd digits (variable) innervation: posterior interosseous nerve actio...
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Extensor digitorum brevis muscle

The extensor digitorum brevis muscle is a muscle on the dorsal surface of the foot which helps extend digits 2 through 4. Summary origin: superolateral surface of calcaneus insertion: lateral sides of the tendons of extensor digitorum longus of toes II to IV action: extension of toes II to I...
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Extensor digitorum longus muscle

Extensor digitorum longus (EDL) is a thin muscle situated in the anterior leg lateral to extensor hallucis longus and extends the lateral four toes. Summary origin: upper two thirds of anterior shaft of fibula, superior portion of the anterior surface of the interosseous membrane, superior tib...
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Extensor expansion

The extensor expansions (also known as the extensor hood or dorsal digital expansion)​ are triangular aponeuroses by which the extensor tendons insert onto the phalanges. Gross anatomy On the dorsal aspect of the fingers, the tendons of the long extensors of the posterior forearm (extensor dig...

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