Items tagged “variant”

372 results found

Aberrant internal carotid artery

Aberrant internal carotid artery is a variant of the internal carotid artery (ICA) and represents a collateral pathway resulting from involution of the normal cervical portion (first embryonic segment) of the ICA 5. There is consequent enlargement of the usually small collaterals which course t...

Anterior shoulder capsular insertion

The anterior capsular insertion, unlike the posterior aspect of the shoulder joint capsule which has a constant scapular attachment along the margins of the glenoid labrum, inserts a variable distance from the labrum. The capsular insertions are classified as follows: type I: at or very near t...

Asymmetrically large jugular bulb

Asymmetrically large jugular bulbs are entirely normal and asymptomatic; its only significance is to distinguish it from pathology. The size of the jugular bulbs is variable, with the right side being significantly larger than the left in two-thirds of people. A normal but large bulb will have...

Bicornuate uterus

A bicornuate uterus is a type of uterine duplication anomaly. It can be classified as a class IV Mullerian duct anomaly. Epidemiology Overall, congenital uterine anomalies occur in ~1.5% of females (range 0.1-3%). Bicornuate uteri are thought to represent ~25% (range 10-39%) of Mullerian duct ...

Bifid rib

Bifid or forked ribs are uncommon. They are thought to occur in ~0.2% of the population and there may be a female as well as right-sided predilection 2. Clinical presentation Usually asymptomatic, they may cause musculoskeletal pain or intercostal nerve entrapment. A bifid first rib is an unco...

Bovine arch

Bovine arch is the most common variant of the aortic arch and occurs when the brachiocephalic (innominate) artery shares a common origin with the left common carotid artery.  A bovine arch is apparent in ~15% (range 8-25%) of the population and is more common in individuals of African descent. ...

Buford complex

Buford complex is a congenital glenoid labrum variant where the anterosuperior labrum is absent in the 1-3 o'clock position and the middle glenohumeral ligament is thickened (cord-like) and originates directly from the superior labrum at the base of the biceps tendon and crosses the subscapulari...

Caval variants

Many caval variants exist, due to the complex embryology of the venous system. These are important for a number of reasons:  not to confuse them with pathology suggest the presence of frequently associated other abnormalities planning of vascular intervention or surgery Types superior vena ...

Cavum septum pellucidum

Cavum septum pellucidum (CSP), or more grammatically correct cavum septi pellucidi, 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 communi...

Cavum vergae

The cavum vergae (CV), along with the cavum septum pellucidum (CSP) is a persistence of the embryological fluid-filled space between the leaflets of the septum pellucidum and is a common anatomical variant. The CV is sometimes referred to as the 6th ventricle 3.  Gross anatomy The CV is the po...

Coracoclavicular joint

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

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 condition is congenital, frequently bilateral (up to 50%) and has been reported in twins, although no ...

Ductus diverticulum

Aortic ductus diverticulum is a developmental outpouching of the thoracic aorta. Gross anatomy It is usually seen at the anteromedial aspect of the aorta at site of the ligamentum arteriosum, at the aortic isthmus. This is also the site of 90% of post-traumatic aortic injuries as the ligamentu...

Horseshoe kidney

Horseshoe kidneys are the most common type of renal fusion anomaly. They render the kidneys susceptible to trauma and are an independent risk factor for the development of renal calculi and transitional cell carcinoma of the renal pelvis. Epidemiology Horseshoe kidneys are found in approximate...

Glenoid labrum variants

There are a number of glenoid labral variants, whose importance is mainly due to the fact that the unwary may misinterpret them as pathology (e.g. Bankart lesion or labral tear). These include: Buford complex sublabral foramen superior sublabral sulcus

Left-sided superior vena cava

A left-sided superior vena cava (SVC) is the most common congenital venous anomaly in the chest, and in a minority of cases can result in a right-to-left shunt 3-4. Epidemiology A left-sided SVC is seen in 0.3-0.5% of the normal population and in ~5% of those with congenital heart disease 3. I...

Sphenoethmoidal air cell

Sphenoethmoidal air cell, also commonly known as the Onodi air cell, is an anatomical variant of the paranasal sinuses, important due to its close proximity to the optic nerve and internal carotid artery. Terminology The sphenoethmoidal air cell is generally defined as the posteriormost ethmoi...

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...

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...

Pancreatic ducts

The pancreatic ductal embryology is moderately complicated, leading to a number of anatomical variants of the pancreatic ducts, many of which are clinically significant. The normal arrangement is for the entire pancreas to be drained via a single duct, to the ampulla of Vater through the sphinc...

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