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.

2,521 results found
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Notochord

The notochord represents the earliest foetal axial skeleton, and extending from the Rathke's pouch to the coccyx. It is a primitive cell line in which the skull base and the vertebral column develop around. The notochord which is cylindrical in shape is replaced by sclerotomes that produce carti...
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Os hypolunatum

The os hypolunatum is an accessory ossicle of the wrist seen lying between the scaphoid and lunate carpal bones, lying at the most proximal border of the capitate bone 1. Due to its position, it should be carefully assessed in clinical context so as not to mistake it for a fracture of an adjacen...
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Mega cisterna magna

Mega cisterna magna refers to a normal variant characterised by a truly focal enlargement of the CSF-filled subarachnoid space in the inferior and posterior portions of the posterior cranial fossa. It is an incidental finding on neuroimaging, and no imaging follow up is necessary.  Epidemiology...
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Mandibular fossa

The mandibular fossa or glenoid fossa is the smooth concave articular surface formed by both the squamous and petrous parts of the temporal bone. It forms the superior articular part of the temporomandibular joint and lodges the condyle of mandible.
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Temporal bone

The temporal bone is situated on the sides and the base of the cranium and lateral to the temporal lobe of the cerebrum. The temporal bone is one of the most important calvarial and skull base bones. The temporal bone is very complex and consists of five parts: squamous part mastoid part petr...
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Calcaneus

The calcaneus, also referred to as the calcaneum, is the largest tarsal bone and the major bone in the hindfoot. It articulates with the talus superiorly and the cuboid anteriorly and shares a joint space with the talonavicular joint, appropriately called the talocalcaneonavicular joint. The cal...
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Peroneal tubercle

The peroneal tubercle (also known as the peroneal trochlea) is one of the two bony projections or protuberances that may be seen on the lateral aspect of the calcaneus, the other one being the retrotrochlear eminence. The peroneal tubercle is present immediately inferior to the fibular malleolu...
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Bochdalek's flower basket

Bochdalek's flower basket is the eponymous name for the incidental finding of protrusion of the choroid plexus through the foramina of Luschka. This is a relatively common finding. It is an important normal variant to recognise as the presence of protruding calcified choroid tissue in the fourt...
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Lateral collateral ligament of the knee

The lateral (fibular) collateral ligament is a cord-like ligament on the lateral aspect of the knee and forms part of the posterolateral corner.  Gross anatomy It originates from the lateral femoral epicondyle and has an oblique course, is joined by the biceps femoris tendon forming the conjoi...
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Caudate nucleus

Caudate nuclei are paired nuclei which along with the globus pallidus and putamen are referred to as the corpus striatum, and collectively make up the basal ganglia. The caudate nuclei have both motor and behavioural functions, in particular maintaining body and limb posture, as well as controll...
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Interphalangeal joint sesamoid (hand)

A sesamoid bone at the interphalangeal joint of the hand is relatively common position for occurrence of a sesamoid bone. It may be present in around 67% of the adult population 1.  They are typically seen as a single small corticated ossicle adjacent to the volar margin of the interphalangeal j...
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Ligament of Treitz

The ligament of Treitz, also known as the suspensory ligament of the duodenum, is a double fold of peritoneum suspending the duodenojejunal flexure from the retroperitoneum. It is often used interchangeably with duodenojejunal (DF) flexure. Anatomy The ligament of Treitz is comprised of two p...
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Nonchromaffin paraganglion cells

Nonchromaffin paraganglion cells are cells in the neuroendocine system that make up several clusters of chemoreceptive cells. These cells are associated with a supporting maxtrix and are found in close proximity to blood vessels and nerves (especially the glossopharyngeal and vagus nerves). They...
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Labelled imaging anatomy cases

This article lists a series of labelled imaging anatomy cases by system and modality. Brain, head and neck CT head: non-contrast axial CT head: non-contrast coronal CT head: non-contrast sagittal CT head: bone window skull axial base CT head: bone window axial calvarium MR head: T2 axial ...
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Apophysis of the proximal 5th metatarsal

The apophysis of the proximal 5th metatarsal lies laterally and is oriented longitudinally parallel to the shaft. Apophysis of the fifth metatarsal base appears on plain radiographs at age 12 for boys and 10 for girls. Fusion of the apophysis to the metatarsal base usually occurs within the fol...
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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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Postcentral gyrus

The postcentral gyrus lies in the parietal lobe, posterior to the central sulcus. It is the site of the primary somatosensory cortex. The somatosensory homunculus is the representation of the distribution of the contralateral body parts on the gyrus. Blood supply The main blood supply is from ...
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Homunculus

A homunculus is a topographical-organised map of the proportional representation of the contralateral somatosensory or motor neurons on the cortex or passing though a part of the brain. The maps are often comical, as the body parts are disproportionally represented compared to their physical siz...
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Olecranon bursa

The olecranon bursa is a bursa located in the subcutaneous tissue that overlies the olecranon process of the proximal ulna. The floor of the bursa lies on the triceps brachii tendon and olecranon, while the roof is in contact with the overlying subcutaneous tissue 1. It is a thin-walled sac line...
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Foramen of Morgagni

The foramina of Morgagni, also known as the sternocostal triangles, are small defects in the posterior aspect of the anterior thoracic wall between the sternal and costal attachments of the diaphragm. The internal thoracic vessels descend through these foramina to become the superior epigastric ...
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Middle hepatic artery

The middle hepatic artery (MHA) is an intrahepatic hilar arterial branch, usually arising from the left hepatic artery, which supplies segments IVa and IVb. It runs towards the right side of the umbilical fissure. Variant anatomy it may arise from the right hepatic artery 1,2 it may arise as ...
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Tunica albuginea (testis)

The tunica albuginea (TA) forms the fibrous covering of the testis and is itself covered by the serous layer, the tunica vaginalis. The covering is total, except for at the point of attachment of the epididymis, and a small defect posteriorly where the spermatic cord vessels enter and leave the ...
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Variant hepatic arterial anatomy

Variation in hepatic arterial anatomy is seen in 40-45% of people. Classic branching of the common hepatic artery from the coeliac artery, and the proper hepatic artery into right and left hepatic arteries to supply the entire liver, is seen in 55-60% of the population.  Terminology An accesso...
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Left hepatic artery

The left hepatic artery (LHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver. Gross anatomy The PHA bifurcates into the left and right hepatic arteries at or before reaching the porta hep...
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Right hepatic artery

The right hepatic artery (RHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver. Gross anatomy The PHA bifurcates into the right and left hepatic arteries at or before reaching the porta he...
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Cavum septum pellucidum

Cavum septum pellucidum (CSP) ("hollow" septum pellucidum) is a normal variant CSF space between the leaflets of the septum pellucidum. Terminology It is sometimes called the fifth ventricle, but this term is not in current use as a CSP does not have any direct communication with the ventricul...
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Os subfibulare

Os subfibulare is an accessory ossicle that lies at the tip of the lateral malleolus of the ankle and is rarely reported 1. Clinical presentation Os subfibulare are usually asymptomatic although they may eventually cause painful syndromes or degenerative change in response to overuse and traum...
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Falciform ligament

The falciform ligament is a broad and thin peritoneal ligament. It is sickle-shaped (Latin: "falciform") and a remnant of the ventral mesentery of the fetus. It is situated in an anteroposterior plane but lies obliquely so that one surface faces forward and is in contact with the peritoneum beh...
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Hepatic artery proper

The hepatic artery proper (or proper hepatic artery) is the continuation of the common hepatic artery after it gives off the gastroduodenal artery. Gross anatomy Course The hepatic artery proper runs anteromedial to the portal vein and medial to the common bile duct to form the portal triad w...
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Vermis

Gross anatomy The vermis (pl: vermes) of the cerebellum is an unpaired medial structure which separates the cerebellar hemispheres. The neocerebellar posterior lobes join in the midline behind the primary fissure to separate the vermis into superior and inferior portions. The vermis can be furt...
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Anterior fontanelle

The anterior fontanelle (or fontanel) is the diamond-shaped soft membranous gap at the junction of the coronal and sagittal sutures. It persists until approximately 18-24 months after birth, after which it is known as the bregma. It is the largest of the fontanelles and is the main sonographic w...
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Os styloideum

The os styloideum is an accessory ossicle of the wrist, situated between the 2nd and 3rd metacarpal bases. Radiographic appearance Given its position next to the 2nd and 3rd metacarpal bases, it may be mistaken for a fracture, though this should not occur if an adequate lateral radiograph is a...
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Os triangulare

The os triangulare (also known as the os intermedium antebrachii or os triquetrum secundarium) is an accessory ossicle located between the ulnar styloid, lunate and triquetrum 1,2. They may be unilatreal or bilateral and the main differential diagnosis is non-union of an ulnar styloid process f...
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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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Asterion

The asterion is the junction on the side of the posteroinferior calvarium where three sutures meet: parietomastoid suture occipitomastoid suture lambdoid suture It represents the site of the closed mastoid fontanelle. It is located at the posterior end of the parietotemporal suture, whereas ...
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Mastoid fontanelle

The mastoid or posterolateral fontanelles are paired bilateral soft membranous gaps at the junction of the parietomastoid, occipitomastoid, and lambdoid sutures. Each mastoid fontanelle persists until the second year of life, after which it is known as the asterion. It can be used as an addition...
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Posterior fontanelle

The posterior fontanelle (or fontanel) is the triangular soft membranous gap at the junction of the lambdoid and sagittal sutures. It persists until approximately 3 months after birth, after which it is known as the lambda. It can be used as an additional sonographic window for performing crania...
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Sphenosquamosal suture

The sphenosquamosal suture is a vertical cranial suture between the sphenoid and temporal bones bilaterally. It is formed by the articulation between the posterior border of the greater wing of the sphenoid bone and the anterior border of the squamous part of the temporal bone 1. It is located l...
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Talocalcaneal coalition

Talocalcaneal coalition is one of the two most common sub-types of tarsal coalition, the other being calcaneonavicular coalition. It accounts for 45% of all tarsal coalitions, and although all three facets of the talocalcaneal joint can be involved, the middle facet is most commonly involved.  ...
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Sphenofrontal suture

The sphenofrontal suture is a cranial suture where the frontal bone meets the sphenoid bone bilaterally. From an anterior perspective of the skull, this suture appears in the roof of the bony orbits. From a lateral perspective, it appears as the meeting of the inferoposterior edges of the fronta...
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Cranial vault

The cranial vault, also known as the skull vault, skullcap or calvaria, is the cranial space that encases and protects the brain together with the base of the skull (chondrocranium). The cranial vault and the base of skull together form the neurocranium. Terminology Although commonly seen in r...
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Occipitotemporal suture

The occipitotemporal/occipitomastoid suture is the obliquely oriented articulation of the anterior border of the squamous occipital bone and the mastoid portion of the temporal bone. A mastoid foramen is occasionally located near or in it. The occipitotemporal suture and the parietotemporal sut...
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Lambdoid suture

The lamdboid suture is the junction between the superior border of the occipital bone and the posterior borders of the right and left parietal bones. It normally fuses at approximately 26 years of age.
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Sagittal suture

The sagittal suture is the midline articulation that joins the two parietal bones. Related pathology premature fusion of the sagittal suture results in scaphocephaly normal fusion of the sagittal suture occurs at approximately 22 years of age
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Squamosal suture

The squamosal or squamous suture is the cranial suture between the temporal and parietal bones bilaterally. From the pterion, it extends posteriorly, curves inferiorly and continues as the parietotemporal suture. Along with growth of the pterion, the asterion and at the frontozygomatic suture, ...
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Accessory anterior inferior tibiofibular ligament

The accessory anterior inferior tibiofibular ligament (AITFL), also known as Bassett's ligament, can be a cause of anterior ankle impingement syndrome. The accessory AITFL is described as a separate thickened distal fascial of the AITFL with a far distal extension on the lateral malleolus. 
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Accessory parotid gland

Accessory parotid glands are a normal variant and represent ectopic salivary tissue separate from, but usually in close proximity to, the main parotid glands. Epidemiology Accessory parotid glands are commonly picked up incidentally on ultrasound; seen in ~20% of the general population 2. Gro...
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Distal tibiofibular syndesmosis

The tibiofibular syndesmosis is a complex fibrous joint composed of multiple ligaments and a broad fibrous membrane (the 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 f...
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Parotid gland

The parotid gland is the largest of the salivary glands and secretes saliva via the parotid duct into the oral cavity to facilitate mastication and swallowing. It is located in the parotid space.  Gross anatomy The parotid gland is wrapped around the mandibular ramus and extends to a position ...
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Lambda

The lambda is the midline bony landmark where the lambdoid sutures and sagittal suture meet, between the occipital and two parietal bones. It may be a depression and therefore palpable. Accessory occiptal bones are common near the lambda, usually associated with the lambdoid sutures. It is the ...
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Optic nerve

The optic nerve is the second cranial nerve which along with the olfactory nerve (CN I) is really an extension of the central nervous system, not surrounded by Schwann cells with first sensory bipolar cell body located peripherally in the retina. Their central processes synapse on ganglion cells...
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Azygos continuation of the inferior vena cava

Azygos continuation of the inferior vena cava (also known as absence of the hepatic segment of the IVC with azygos continuation) is an uncommon vascular anomaly and is a cause of a dilated azygos vein. Epidemiology Azygos continuation of the IVC has a prevalence ~1.5% (range 0.2-3%) 1. Clinic...
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Typical ribs

Typical ribs are those numbered 2 to 10 with ribs 1, 11 and 12 considered atypical. Gross anatomy A typical rib is long and flat. They contain a: head neck tubercle shaft angle Ribs have a rounded, smooth superior border. The inferior border is thin and sharp.  Osteology Head The head...
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Inion

The inion is the tip of external occipital protuberance (EOP), the midline bony prominence in the occipital bone where the ligamentum nuchae and trapezius muscle attaches. It is usually easily palpable. It is the the surface marking of the internal attachment of the tentorium cerebelli. It is ...
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Left paraspinal line

The left paraspinal (also known as the paraspinous or paravertebral) line (or stripe) is a feature of frontal chest x-rays. It is formed by the interface between the left lung and the left posterior mediastinal soft tissues 1. It is more commonly seen than the right paraspinal line. Lateral dis...
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Left paratracheal stripe

The left paratracheal stripe is formed by the interface of the medial pleural surface of the left upper lobe and left lateral border of the trachea and/or the fat adjacent 1 with air within each structure forming the outline. It may not be visible if the left upper lobe contacts the left subclav...
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Vertebral artery

The vertebral arteries (VA) are paired arteries, each arising from the respective subclavian artery and ascending in the neck to supply the posterior fossa and occipital lobes, as well as provide segmental vertebral and spinal column blood supply. Summary origin: branches off the 1st part of t...
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Limbus vertebra

Limbus vertebra is a well-corticated unfused secondary ossification centre, usually of the anterosuperior vertebral body corner, that occurs secondary to herniation of the nucleus pulposus through the vertebral body endplate beneath the ring apophysis (see ossification of the vertebrae). These a...
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Chest x-ray lines and stripes

Chest x-ray lines and stripes are important to recognise on chest radiographs.  Lines are usually less than 1 mm in width and are comprised of tissue outlined on either side by air and typically represent pleural-covered structures within the middle and superior mediastinum 1,2: anterior junct...
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Posterior wall of bronchus intermedius

The posterior wall of bronchus intermedius, also known as the intermediate stem line, is a stripe formed by the interface of the posterior wall of bronchus intermedius and the air within the azygo-oesophageal recess 1. It normally measures between 0.5-2 mm in thickness but is not considered abn...
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Azygo-oesophageal recess

The azygo-oesophageal recess (also known as the line/interface) (AER) is a prevertebral space formed by the interface of the posteromedial segments of the right lower lobe and the azygos vein and oesophagus 1-3. The AER extends from the azygos arch to the aortic hiatus and has the following bord...
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Aortic-pulmonary stripe

The aortic-pulmonary stripe is an uncommon feature of frontal chest radiographs and was first described by Keats in 1972 1. It is formed by the interface of the pleural surface of the anterior segment of the left upper lobe contacting the mediastinal fat that is anterolateral to the pulmonary t...
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Right paraspinal line

The right paraspinal (also known as the paraspinous or paravertebral) line (or stripe) is a feature of frontal chest x-rays and is formed by the interface of the right lung and the posterior mediastinal soft tissue.  Lateral displacement of the right paraspinal line can be due to 1-3: osteophy...
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Posterior tracheal stripe

The posterior tracheal stripe (or line) is formed by air in the trachea and air in the right lung outlining the intervening posterior wall of the trachea and soft tissue. It is seen on lateral chest x-rays and normally measures less than 2.5 mm in width 1,2. Abnormal thickening has a variety of ...
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Posterior junction line

The posterior junction (or junctional) line is formed by the apposition of the pleural surfaces of the posteromedial surfaces of the upper lobes of the lungs, posteriorly to the oesophagus but anterior to the thoracic spine (usually T3-T5) 1,2. There are many causes for an abnormal appearance o...
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Anterior junction line

The anterior junction (or junctional) line is a feature of frontal chest radiographs and chest CTs. It is a result of the parietal and visceral pleura meeting anteromedially. It normally contains a small amount of fat but can form a stripe of variable thickness if there is a lot of fat present o...
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Thyroid gland

The thyroid gland is an endocrine organ in the neck which is completely enveloped by pretracheal fascia (middle-layer of the deep cervical fascia) and lies in the visceral space.  Gross anatomy The thyroid extends from C5 to T1 and lies anterior to the thyroid and cricoid cartilages of the lar...
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Os supratalare

An os supratalare is an accessory ossicle of the foot located at the superior aspect of the talar head or neck. It has a reported incidence of ~1% (range 0.2-2.4%) 1. It is almost always asymptomatic.  Differential diagnosis os supranaviculare is also anatomically seen in close proximity to th...
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Os tibiale externum

An os tibiale externum, also known as an accessory navicular or os naviculare accessorium, is a large accessory ossicle that can be present adjacent to the medial side of the navicular bone. The tibialis posterior tendon often inserts with a broad attachment into the ossicle. Most cases are asym...
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Suprapatellar bursa

The suprapatellar bursa, also known as the suprapatellar recess, is one of several bursae of the knee. It is located proximal to the knee joint, between prefemoral and suprapatellar fat pads. As with all bursae, its purpose is to reduce friction between moving structures. In most (~85%) people,...
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Floor of mouth

The floor of mouth is an oral cavity subsite and is a common location of oral cavity squamous cell carcinoma.  Gross anatomy The floor of mouth is a U-shaped space which extends (and includes) from the oral cavity mucosa superiorly, and the mylohyoid muscle sling 2,3.  Boundaries superiorly:...
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Liver sinusoid

Liver sinusoids are a type of fenestrated/porous blood vessel which compose the 'capillary bed' of the liver parenchyma. They receive terminal branches of the oxygen-rich hepatic artery (terminal hepatic arterioles) and nutrient-rich portal vein (terminal portal venules). They facilitate vascula...
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Portal vein

The portal vein (PV) (sometimes referred to as the main or hepatic portal vein) is the main vessel in the portal venous system and drains blood from the gastrointestinal tract and spleen to the liver. Gross anatomy The portal vein usually measures approximately 8 cm in length in adults with a ...
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Pituitary fossa

The pituitary (hypophyseal) fossa or sella turcica is a midline, dural lined structure in the sphenoid bone, which houses the pituitary gland. Gross anatomy The anterior, inferior and posterior walls are bony, while the lateral walls and roof are formed by dural slings between the anterior and...
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Interpeduncular cistern

The interpeduncular cistern (or basal cistern) is one of the subarachnoid cisterns. It is a wide CSF- filled cavity between the two temporal lobes anteriorly and encloses the cerebral peduncles as well as structures contained within the interpeduncular fossa. It is continuous anteriorly with the...
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Hard palate

The hard palate is the anterior horizontal bony part of the palate that forms the roof of the oral cavity and floor of the nasal cavity. Most of the hard palate is formed by the palatine processes of the maxillae, the horizontal plates of the palatine bones complete it posteriorly. On its inferi...
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Great vessel space

The great vessel space is the fourth retroperitoneal space along with the anterior and posterior pararenal spaces, and the perirenal space 1,2. Unlike other retroperitoneal spaces, it is not well-defined by fascial planes and thus disease processes affecting other retroperitoneal spaces can also...
Article

Periaqueductal grey matter

Periaqueductal grey (PAG) matter is a column of grey matter that surrounds the cerebral aqueduct of Sylvius in the midbrain. The PAG extends from the superior border of the midbrain (which forms the posterior aspect of the floor of the third ventricle), inferiorly towards the fourth ventricle an...
Article

Retrotrochlear eminence

The retrotrochlear eminence is located posterior to the peroneal tubercle and the peroneal tendons. It is one of two bony projections or protuberances that may be seen arising from the lateral wall of the calcaneum, the other being the peroneal tubercle. It is seen to be prominent in individua...
Article

Focal fatty deposits in spinal bone marrow

Focal fatty deposits/replacement in spinal bone marrow are well-defined focal fat islands within the bone marrow of spine or other parts of axial skeleton. Epidemiology Common in older individuals, related to age but not to sex. Pathology This process is a normal variant. Histologically, it ...
Article

Anatomical variants

Anatomical variants represent the deviations from the accepted standard human anatomy as printed in the classic textbooks (e.g. Gray's Anatomy 1), and taught in universities, dissecting rooms and clinical practice. Terminology The term "normal anatomic variants" or just "normal variants" is of...
Article

Lunotriquetral coalition

Lunotriquetral coalition is the most common type of carpal coalition and represents a congenital fusion of the lunate and triquetral bones of the carpus.  Epidemiology Lunotriquetral coalition is the most common type of carpal coalition with a prevalence of 0.1%. It is more common in females (...
Article

Middle thyroid vein

The middle thyroid vein is a tributary of the internal jugular vein. Gross anatomy Origin and course The middle thyroid vein arises from the lateral surface of the thyroid. It traverses laterally to the internal jugular vein, passing anterior to the common carotid artery and posterior to the ...
Article

Plantaris muscle

The plantaris muscle is one of the calf muscles in the superficial posterior compartment of the leg. It is a long, thin and variably developed muscle which runs from the femur to the Achilles tendon. Summary origin: posterosuperior aspect of the lateral femoral condyle and the oblique poplitea...
Article

Spring ligament complex

The spring (plantar calcaneonavicular) ligament complex is a group of ligaments that connect the calcaneum and navicular, and support the talus. The ligaments include: superomedial ligament forms a sling, suspending/articulating against the head of talus merges with the inferior aspect of ti...
Article

Gluteal muscles

The superficial gluteal muscles lie within the gluteal region posterolateral to the bony pelvis and proximal femur. From superficial to deep lie the gluteus maximus, medius and minimus. The gluteus maximus is an important muscle for hip extension and lateral rotation. Gluteus medius and minimus ...
Article

Calcaneal tendon

The calcaneal tendon, commonly known as the Achilles tendon, is the strongest and largest tendon of the human body. It is also one of the commonest tendons to become injured due to its high biomechanical load but poor vascularity 2. Gross anatomy The calcaneal tendon forms by the merging of fi...
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Pyramidal lobe of thyroid

The pyramidal lobe of thyroid is a normal anatomic variant. It is seen as a third thyroid lobe and is present in 10-30% of the population. It represents a persistent remnant of the thyroglossal duct. It usually arises from the right or left side of the isthmus extending in a cranial direction; ...
Article

Pericardium

The pericardium is a conical, flask-like, fibroserous sac which contains the heart and the roots of the great vessels and defines the middle mediastinum.  Gross anatomy The pericardium is made of two sacs in one. The outer sac is the fibrous pericardium and the inner sac is the double-layered ...
Article

Pars tensa

The pars tensa is the tense portion of the tympanic membrane and refers to the main portion of the membrane. It extends from the anterior and posterior malleolar folds at the level of the lateral process of malleus to the inferior extent of the tympanic membrane at its attachment. Associated p...
Article

Tympanic membrane

The tympanic membrane is a thin membrane that separates the external ear from the middle ear. It acts to transmit sound waves from air in the external auditory canal (EAC) to the ossicles of the middle ear. Gross anatomy The tympanic membrane is shaped like a flat cone pointing into the middle...
Article

Prussak space

Prussak space is a subcomponent of the lateral epitympanic space and extends from the level of the scutum to the umbo. This space is best demonstrated on the oblique coronal image.  Gross anatomy Boundaries lateral: pars flaccida of the tympanic membrane medial: neck of the malleus  superio...
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Transition zone

The transition zone of a nerve describes a roughly 2 mm length region where the myelin sheath changes from central to peripheral type. This zone is susceptible to mechanical irritation and is implicated in neurovascular compression syndromes such as trigeminal neuralgia (CN V), hemifacial spasm ...

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