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.

2,268 results found
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Abdominal and pelvic anatomy

Abdominal and pelvic anatomy encompasses the anatomy of all structures of the abdominal and pelvic cavities.
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Abdominal aorta

The abdominal aorta is the main blood vessel in the abdominal cavity that transmits oxygenated blood from the thoracic cavity to the organs within the abdomen and to the lower limbs. Summary origin: continuation of descending thoracic aorta at T12  course: descends anterior and slightly to th...
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Abdominal cavity

The abdominal cavity is divided into two major compartments, the peritoneum and retroperitoneum, early in fetal development. The parietal peritoneum is reflected over the peritoneal organs to form a series of supporting peritoneal ligaments, mesenteries and omenta. The peritoneal reflections ca...
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Abdominal surface anatomy

The abdomen, when looking from in front, is divided into nine regions by imaginary planes (two vertical and two horizontal) forming abdominal surface anatomy. The nine regions are of clinical importance when examining and describing pathologies related to the abdomen. The horizontal planes are o...
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Abducens nerve

The abducens nerve is the sixth cranial nerve. It courses from its nucleus located in the dorsal pons to its innervation of the lateral rectus muscle and can be divided into four parts: nucleus and intraparenchymal portion cisternal portion cavernous sinus portion orbital portion Gross anat...
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Abductor digiti minimi (foot)

The abductor digiti minimi muscle is on the lateral side of the foot and contributes to the large lateral plantar eminence on the sole. Summary origin: lateral and medial processes of calcaneal tuberosity, and band of connective tissue connecting calcaneus with base of metatarsal V insertion:...
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Abductor digiti minimi (hand)

The abductor digiti minimi muscle overlies the opponens digiti minimi. Summary origin: pisiform, the pisohamate ligament, and tendon of flexor carpi ulnaris insertion: 5th proximal phalanx action: abducts 5th finger at metacarpophalangeal joint arterial supply: ulnar artery innervation: de...
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Abductor hallucis muscle

The abductor hallucis muscle forms the medial margin of the foot and contributes to a soft tissue bulge on the medial side of the sole. Summary origin: medial process of calcaneal tuberosity insertion: medial side of base of proximal phalanx of great toe action: abducts and flexes great toe ...
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Abductor pollicis brevis

The abductor pollicis brevis is a thin subcutaneous muscle located laterally in the thenar eminence of the hand. Summary origin: mainly from the flexor retinaculum few fibres originate from the tubercles of scaphoid and trapezium and tendon of abductor pollicis longus accessory slips may ori...
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Abductor pollicis longus

The abductor pollicis longus (APL) is a muscle found in the deep layer of the posterior compartment of the forearm. As it descends, it becomes superficial and passes under the extensor retinaculum and through the 1st extensor compartment of the wrist before attaching distally. Summary origin: ...
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Aberrant arachnoid granulations

Aberrant arachnoid granulations (AbAG) are arachnoid granulations that penetrated the dura but failed to migrate normally in the venous sinus. They are most often located in the greater wing of the sphenoid bone. Occasionally, they are seen in the posterior temporal bone wall. Clinical presenta...
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Aberrant left pulmonary artery

Aberrant left pulmonary artery, also known as pulmonary sling, represents an anatomical variant characterised by the left pulmonary artery arising from the right pulmonary artery and passing above the right main bronchus and in between the trachea and oesophagus to reach the left lung. It may le...
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Aberrant right subclavian artery

Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are the commonest of the aortic arch anomalies 2.  Epidemiology The estimated incidence is 0.5-2%. Clinical presentation They are often asymptomatic, but around 10% of people may complain of tracheo-oesophageal symptom...
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Abnormal renal rotation

Abnormal renal rotation (renal malrotation) refers to an anatomical variation in the position of the kidneys, in particular to anomalous orientation of the renal hilum. It may occur unilaterally or bilaterally. It is almost always an asymptomatic incidental finding.  Epidemiology Malrotation i...
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Accessory appendicular artery

The accessory appendicular artery (or artery of Seshachalam) is a branch of the posterior caecal artery, which in turn arises from the ileocolic artery, and runs in the mesoappendix. The exact prevalence of this accessory artery and its impact upon the risk of appendicitis varies among studies....
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Accessory breast tissue

Accessory breast tissue is a relatively common congenital condition in which abnormal accessory breast tissue is seen in addition to the presence of normal breast tissue. This normal variant can present as a mass anywhere along the course of the embryologic mammary streak (axilla to the inguinal...
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Accessory fissures of the lung

Accessory fissures of the lung usually occur at the borders of bronchopulmonary segments. They are common normal variants but are less commonly seen on imaging.  Some of the more common accessory fissure include 1: azygos fissure: most commonly seen accessory fissure inferior accessory fissur...
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Accessory gallbladder

Accessory gallbladders are a rare anatomical variant occurring in 0.03% of cases (approximately 1 in 3000 people). They can arise from either the left or right hepatic ducts or both. Accessory gallbladders arise from a bifid diverticulum of the hepatic duct in the 5th or 6th week of development ...
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Accessory hemiazygos vein

The accessory (or superior) hemiazygos vein forms part of the azygos system and along with the hemiazygos vein, it is partially analogous to the right-sided azygos vein. It drains the left superior hemithorax.  Gross anatomy Origin and course The accessory hemiazygos vein is formed by the con...
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Accessory left atrial appendage

An accessory left atrial appendage is a frequent fortuitous finding in cardiac imaging, encountered in ~10% of patients. They are more often seen as a small diverticular structure projecting from the right upper side of the left atrial wall. Differential diagnosis it must not be confused with ...
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Accessory meningeal artery

The accessory meningeal artery is a branch of the maxillary artery but can also branch from the middle meningeal artery. The artery passes upwards through the foramen ovale to supply the trigeminal ganglion and the dura mater of Meckel's cave and the middle cranial fossa. It also usually suppli...
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Accessory middle cerebral artery

The accessory middle cerebral artery is a variant of the middle cerebral artery (MCA) that arises from the anterior cerebral artery (ACA). It is different from a duplicated middle cerebral artery, in which the duplicated vessel originates also from the distal end of the internal carotid artery (...
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Accessory occipital bone sutures

The parietal and occipital bones in particular are common regions for accessory sutures because of their multiple ossification centres. The occipital bone has complex development, ossifying from six centres. The foramen magnum is surrounded by four ossification centres. On each side are the exo...
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Accessory ossicle of the anterior arch of the atlas

The accessory ossicle of the anterior arch of the atlas is a normal variant and is best appreciated on a lateral cervical/sagittal study. It is observed as a circular and corticated osseous density that articulates with the inferior aspect of the anterior arch of the atlas.  It is not associate...
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Accessory ossicles

Accessory ossicles are secondary ossification centres that are separate from the adjacent bone. In most cases, they are congenital in origin, although they may occur as a result of trauma or local degenerative disease 2: shoulder and elbow os acromiale os supratrochleare dorsale wrist (mnemo...
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Accessory ossicles of the foot

Accessory ossicles of the feet are common developmental variants with almost 40 having been described. The more common ones include: os peroneum os subfibulare os subtibiale os tibiale externum (accessory navicular) os trigonum os calcaneus secundaris os intermetatarseum pars peronea met...
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Accessory ossicles of the wrist

Accessory ossicles of the wrist are commonly seen on plain radiographs of the wrist and associated cross-sectional imaging. Over 20 were originally described 2, although the more common include 1: lunula: between TFCC and triquetrum os styloideum (carpal boss): on dorsal surface of 2nd or 3rd ...
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Accessory parotid glands

Accessory parotid glands are a normal variant and represent ectopic salivary tissue separate from, but usually in close proximity to, the main parotid glands 1. Occasionally the accessory tissue is contiguous with the main glands. Epidemiology Accessory parotid glands are commonly picked up in...
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Accessory peroneal muscles

Accessory peroneal muscles are a group of accessory muscles that can occur in the foot region as a normal variant in some individuals. The peroneal compartment is known as the lateral compartment of the leg. Peroneus quartus muscle Originally, several accessory muscles were distinguished in th...
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Accessory renal artery

Accessory renal arteries are a common variant and are present in ~25% (range 20-30%) of the population. Their proper identification is of utmost importance for surgical planning prior to live donor transplantation 3,4 and renal artery embolisation for various reasons 5. The term extra renal art...
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Accessory right inferior hepatic vein

An accessory right inferior hepatic vein is the most common variation of the hepatic veins.  It is present in up to 48% of the population and drains the posterior part of the right lobe (mainly segments 6 and 7) directly into the inferior vena cava. Variations in hepatic vascular anatomy are pa...
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Accessory soleus muscle

The accessory soleus muscle is an anatomical variant characterised by an additional distinct muscle encountered along a normal soleus muscle. It is uncommon with a prevalence of ~3% (range 0.7-5.5%). Summary origin: fibula, soleal line of the tibia, or the anterior surface of the soleus muscle...
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Accessory superior acetabular notch

An accessory superior acetabular notch is a normal variant of the acetabulum, which can be seen on radiographs. It may lead to diagnostic confusion, especially in younger patients.  Radiographic features MRI appear as bilateral symmetric fluid-filled pits in the roof of the acetabulum with sh...
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Acetabular foramen

The acetabular foramen is formed by the bony margins of the acetabular notch and completed by the transverse ligament of the hip. From its margins (both transverse ligament and acetabular notch) arises the ligamentum teres. Through it pass nutrient vessels to the femoral head epiphysis.
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Acetabular labrum

Acetabular labrum acts to deepen the acetabulum and increase contact between the pelvis and the femoral head. Its exact biomechanical role remains to be fully elucidated. Gross anatomy The acetabular labrum is a C-shaped fibrocartilaginous structure with an opening anteroinferiorly at the site...
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Acetabular notch

The acetablar notch is a depression in the margin of the acetabulum located anteroinferiorly. It is bridged by the transverse ligament, and thus forms the acteabular foramen. The ligamentum teres has part of its origin from the acetabular notch. 
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Acetabulum

The acetabulum (plural: acetabula) is the large cup-shaped cavity on the anterolateral aspect of the pelvis that articulates with the femoral head to form the hip joint. Gross anatomy All three bones of the pelvis (the ilium, ischium, and pubis) together form the acetabulum. The three bones ar...
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Acromial types

The shape of the acromion had been initially divided into three types (which was known as the Bigliani classification) 3, to which a fourth has been added 2. They are useful as a standardised way of describing the acromion, as well as predicting to a degree the incidence of impingement.  Classi...
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Acromioclavicular joint

The acromioclavicular (AC) joint is a plane synovial joint of the pectoral girdle. Gross anatomy The acromioclavicular joint is between the small facets of the convex distal clavicle and flat medial acromion. The articular surfaces are lined with hyaline cartilage 4. A fibrocartilaginous wedge...
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Acromioclavicular joint configuration

There is much variation in acromioclavicular (AC) joint configuration which may be confused with pathology.  The relationship of the acromion to the distal clavicle at the AC joint can be described in the coronal plane as 1, 2, 3: horizontal: normal low lying: associated with shoulder impinge...
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Acromion

The acromion, also known as the acromial process, is a small section of the scapula that extends anteriorly from the spine of the scapula.  Gross anatomy It forms the acromioclavicular joint with the lateral third of the clavicle, and also connects with the coracoid process via the coraco-acro...
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Adductor brevis muscle

The adductor brevis is a muscle in the medial compartment of the thigh that lies immediately deep to the pectineus and adductor longus. Summary origin: external surface of body of pubis and inferior pubic ramus insertion: posterior surface of proximal femur, linea aspera, medial supracondylar...
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Adductor canal

The adductor canal is a muscular tunnel in the thigh. It commences at the inferior end of the femoral triangle and terminates at the adductor hiatus.  Gross anatomy Boundaries anteriorly: sartorius muscle posteromedially: adductor longus and adductor magnus muscles laterally: vastus mediali...
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Adductor hallucis muscle

The adductor hallucis muscle arises by two heads, an oblique and transverse head. It is responsible for adducting the big toe. Summary origin transverse head: ligaments associated with metatarsophalangeal joints of lateral three toes oblique head: bases of metatarsals II to IV and from sheat...
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Adductor longus muscle

The adductor longus is a muscle in the medial compartment of the thigh that lies anterior to the adductor magnus. Summary origin: external surface of body of pubis (triangular depression inferior to pubic crest and lateral to pubic symphysis) insertion: linea aspera on middle one-third of sh...
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Adductor magnus muscle

The adductor magnus is the largest and deepest of the muscles in the medial compartment of the thigh. Like the adductor longus and brevis muscles, the adductor magnus is a triangular or fan shaped muscle anchored by its apex to the pelvis and attached by its expanded base to the femur. Summary ...
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Adductor pollicis

The adductor pollicis is a large triangular muscle anterior to the plane of the interossei that crosses the palm. Summary origin: transverse head: 3rd metacarpal oblique head: capitate and bases of 2nd and 3rd metacarpals insertion: base of proximal phalanx and extensor hood of thumb actio...
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Adnexa

Adnexa (pl., sing. adnexus) is a general term that refers to the accessory structures of an organ. In general radiological use, the term is often (incorrectly) used synonymously with ovary, an adnexal structure of the uterus. Adnexa have been described with: uterus (adnexa uteri) ovaries, fal...
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Adrenal arteries

The adrenal glands are supplied by three adrenal (suprarenal) arteries:  superior adrenal artery: arises from ipsilateral inferior phrenic artery middle adrenal artery: arises from lateral side of abdominal aorta inferior adrenal artery: arises from the ipsilateral renal artery
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Adrenal gland

The adrenal (suprarenal) glands are paired organs of the endocrine system, often asymmetric in shape.  Gross anatomy Each gland is enclosed in the perirenal fascia and each has a body and two limbs: a medial limb and a lateral limb. However, the right adrenal gland is usually more pyramidal in...
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Adrenal veins

The venous drainage of the adrenal (suprarenal) glands is typically comprised of a single vein draining each adrenal gland. Like the gonadal veins each side drains differently: left suprarenal vein drains into the left renal vein 1. right suprarenal vein drains directly into the inferior vena ...
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Agenesis of the left hepatic lobe

Agenesis of the left hepatic lobe is a rare variation in liver anatomy. It is clinically asymptomatic and discovered during imaging or surgery. Radiographic features absence of the left hepatic lobe (left of the falciform ligament, Couinaud segments II and III) absence of left hepatic artery,...
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Agenesis of the right hepatic lobe

Agenesis of the right hepatic lobe is a rare variation in liver anatomy. Radiographic features absence of the right hepatic lobe absence of right hepatic artery, right portal vein, and right hepatic biliary system compensatory hypertrophy of the left hepatic lobe and caudate lobe possible r...
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Agger nasi cells

Agger nasi air cells are the most anterior ethmoidal air cells lying anterolateral and inferior to the frontoethmoidal recess and anterior and above the attachment of the middle turbinate. They are located within the lacrimal bone and therefore have as lateral relations the orbit, the lacrimal s...
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Alar ligament

The alar ligaments join the lateral margins of the sloping upper posterior margin of the dens of C2 to the lateral margins of the foramen magnum (adjacent to the occipital condyles) and lie on either side of the apical ligament. The may be oblique or vertical and are thickest at the occipital at...
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Alveoli

The alveoli are tiny hollow air sacs that comprise the basic unit of respiration. Gross Anatomy Alveoli are found within the lung parenchyma and are found at the terminal ends of the respiratory tree, clustered around alveolar sacs and alveolar ducts.  Each alveolus is approximately 0.2 mm in ...
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Amastia

Amastia is a rare congenital condition characterised by the absence of breast tissue, nipple and areola. This may occur unilaterally or bilaterally. Pathology During embryological development, breasts first appear as ectoderm ridges during the 6th week of gestation. This ridge grows thicker an...
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Amazia

Amazia is a rare congenital condition defined by the absence of glandular parenchyma in either one or both of the breasts and a normal nipple and areola complex.  Epidemiology This is a very rare entity and the true prevalence is not known. Although there are strict definition criteria, the di...
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Ambient cistern

The ambient cistern is part of the subarachnoid cisterns. Gross anatomy The ambient cistern is a thin, sheet-like extension of the quadrigeminal cistern that extends laterally surrounding around the midbrain and posterior to the thalami. It acts as the connection between the quadrigeminal cist...
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Amnion

Amnion refers to a membranous structure which covers and protects the embryo. It forms inside the chorion. The amnion usually fuses with the outer chorion by around 14 weeks of gestation. Radiographic features Ultrasound The amnion can be visualised in most pregnancies before the 12th week of...
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Amphiarthroses

Amphiarthroses are a functional class of joint that permit a small amount of movement under normal conditions. Examples symphyses (secondary cartilaginous joints) symphysis pubis intervertebral discs sternomanubrial joint  See also  synarthroses diarthroses
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Ampulla of Vater

The ampulla of Vater is a conical structure at the confluence of the common bile duct (CBD) and the main pancreatic duct that protrudes at the major duodenal papilla into the medial aspect of the descending duodenum. The entire structure is encased by smooth muscle fibers that compose the sphinc...
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Amygdala

The amygdala is a very well studied part of the limbic system and forms part of the mesial temporal lobe.  Gross anatomy The amygdala is a complex structure, located dorsomedially in the temporal lobe, forming the ventral superior, and medial walls of the inferior horn of the lateral ventricle...
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Anal canal

The anal canal is the terminal part of the gastrointestinal tract. Anatomically, the anal canal is referred to as the terminal alimentary tract between the dentate line and anal verge. However, histologically it extends more proximally and includes the columns of Morgagni and anal sinuses. Surgi...
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Anal margin

Anal margin or perianal skin is arbitrarily defined as a skin tissue with a radius of 5 cm from the anal verge, consisting of keratinizing squamous epithelial tissue containing hair follicles. See also anal margin neoplasms
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Anal sphincter

The anal sphincter is divided into an internal and external anal sphincter. It surrounds the anal canal.  Gross anatomy Internal anal sphincter continuation of inner rectal muscle thickened, circular muscle fibres, up to 5 mm thick composed of visceral muscle External anal sphincter Compo...
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Anal verge

Anal verge is part of anal region and consists of a band of squamous epithelial tissue lacks hair follicles and extends from inter-sphincteric groove to perianal skin. 
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Anatomical snuff box

The anatomical snuff box is a surface anatomy feature. It appears as a triangular depression on the lateral surface of the wrist on full extension of the thumb. Gross anatomy Boundaries medial: tendons of the extensor pollicis longus lateral: tendons of the extensor pollicis brevis and mor...
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Anatomic position

The anatomic position, also referred to as the standard anatomic position, is the consistent position of the human body in which positional reference is made for anatomical nomenclature. It is not reliant on whether the patient is standing, supine, prone, sitting, etc. The position is defined a...
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Anatomy article structure

Articles pertaining to normal anatomy require a different structure, and the following subheadings are recommended: ========================================================================== As with all other articles, the introductory paragraph should introduce the anatomical term and aim to ...
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Anatomy article structure (bone)

As with all other articles, the introductory paragraph should introduce the anatomical term and aim to give an interesting summary. The first sentence should contain the title of the article in bold.  Summary location: articulations: blood supply and innervation: relations: Gross anatomy ...
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Anatomy article structure (joint)

As with all other articles, the introductory paragraph should introduce the anatomical term and aim to give an interesting summary. The first sentence should contain the title of the article in bold.  Summary location: movement: ligaments and tendons: relations: Gross anatomy Location Mo...
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Anatomy article structure (nerve)

As with all other articles, the introductory paragraph should introduce the anatomical term and aim to give an interesting summary. The first sentence should contain the title of the article in bold.  Summary location: origin and course: branches and supply: relations: Gross anatomy Locat...
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Anatomy article structure (organ)

As with all other articles, the introductory paragraph should introduce the anatomical term and aim to give an interesting summary. The first sentence should contain the title of the article in bold.  Summary location: function: blood supply and drainage: relations: Gross anatomy Location...
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Anatomy article structure (space/region)

As with all other articles, the introductory paragraph should introduce the anatomical term and aim to give an interesting summary. The first sentence should contain the title of the article in bold.  Summary location: boundaries: contents: Gross anatomy Location Boundaries Contents Rel...
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Anatomy article structure (vessel)

As with all other articles, the introductory paragraph should introduce the anatomical term and aim to give an interesting summary. The first sentence should contain the title of the article in bold.  Summary location: origin and termination: branches and supply: relations: Gross anatomy ...
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Anatomy curriculum

The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists. General anatomy Neuroanatomy Head and neck anatomy Thoracic anatomy Abdominal and pelvic anatomy Spinal anat...
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Anconeus

The anconeus is a small muscle in the posterior compartment of the arm at the lateral aspect of the elbow. It has little functional significance but should be differentiated from the variably present anconeus epitrochlearis at the medial aspect of the elbow. Summary origin: lateral epicondyle ...
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Anconeus epitrochlearis

Anconeus epitrochlearis is an accessory muscle at the medial aspect of the elbow. It is also known as the accessory anconeus muscle and should not be confused with the anconeus muscle which is present at the lateral aspect of the elbow.  Epidemiology The muscle may be unilateral but has been f...
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Angle of the longitudinal arch (foot)

The angle of the longitudinal arch is one of the angles drawn on the weightbearing lateral foot radiograph. The angle is formed between the calcaneal inclination axis and a line drawn along the inferior edge of the 5th metatarsal. The normal angle is 150-170°. In pes cavus, as the height of th...
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Angular gyrus

The angular gyrus is a portion of the parietal lobe of the brain. It is one of the two parts of the inferior parietal lobule, the other part being the supramarginal gyrus. It plays a part in language and number processing, memory and reasoning 1. Gross anatomy Relations It lies as a horseshoe...
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Angular vein

The angular vein drains the anterior region of the scalp 1. It is formed by the union of the supratrochlear and supraorbital veins and becomes the facial vein 1,2,3. Gross Anatomy The angular vein is formed at the medial canthus as the supratrochlear vein and supraorbital vein unite 1,2. The a...
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Ankle joint

The ankle joint forms the articulation between the foot and the leg. It is a primary hinge synovial joint lined with hyaline cartilage. Gross anatomy The ankle joint is comprised of the tibia, fibula, talus, and calcaneus as well as the supporting ligaments, muscles and neurovascular bundles. ...
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Annular pancreas

Annular pancreas is a morphological anomaly which can cause duodenal obstruction. This condition is important to recognise, as radiologists are frequently the first to make the diagnosis. Epidemiology The incidence is probably 1 in 250, however incidence is not accurately reported 1. It is as ...
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Annulus fibrosus

The annulus fibrosus surrounds the nucleus polposus and together they form the intervertebral disc. Gross anatomy The annulus comprises 15 to 20 collagenous (type I) laminae which run obliquely from the edge of one vertebra down to the edge of the vertebra below. The direction of the fibres al...
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Anomalous course of coronary arteries

Anomalous course of a coronary artery is a type of congenital coronary artery anomaly. It may represent a benign and incidental finding, but can also be a malignant course predisposing patients to life-threatening myocardial ischaemia or arrhythmias, depending on where the artery runs.  Clinica...
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Ansa cervicalis

The ansa cervicalis is a component of the cervical plexus which gives muscular branches to the geniohyoid muscle of the suprahyoid group and all 4 of the infrahyoid muscles.  Gross anatomy Roots superior root: derived from the anterior primary rami of C1 inferior root: derived from the anter...
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Ansa pancreatica

The ansa pancreatica is a rare type of anatomical variation of the pancreatic duct. It is a communication between the main pancreatic duct (of Wirsung) and the accessory pancreatic duct (of Santorini). Recently, the ansa pancreatica has been considered as a predisposing factor in patients with i...
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Anterior abdominal wall

The anterior abdominal wall forms the anterior limit of the abdominal viscera and is defined superiorly by the xiphoid process of the sternum and costal cartilages and inferiorly by the iliac crest and pubic bones of the pelvis. Gross anatomy The anterior abdominal wall has seven layers (from ...
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Anterior angulation of the coccyx

Anterior angulation of the coccyx may be a normal variant but poses a diagnostic challenge for those considering coccygeal trauma. Classification Four types of coccyx have been described: type I: the coccyx is curved slightly forward, with its apex pointing caudally (~70%) type II: the coccy...
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Anterior atlanto-occipital membrane

The anterior atlanto-occipital membrane is a thin membrane that joins the upper border of the anterior arch of the atlas (C1) to the anterior inferior surface of the foramen magnum. It is a continuation of the anterior longitudinal ligament above the C1 level. It is immediately posterior to the ...
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Anterior cardiac veins

The anterior cardiac veins are a group of parallel coronary veins that course over the anterior surface of the right ventricle, draining it and entering directly into the right atrium. They may occasionally drain into the small cardiac vein. 
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Anterior cardinal veins

The anterior cardinal veins are paired transient embryologic venous vessels which deliver venous return to the heart starting at about 4 weeks of gestation 1. Embryogenesis The anterior cardinal veins begin their embryological development as symmetric venous channels draining blood from the cr...

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