Items tagged “variant”

Aberrant internal carotid artery is a variant of the internal carotid artery and represents a collateral pathway resulting from involution of the normal cervical portion (first embryonic segment) of the internal carotid artery 5. Gross anatomy There is consequent enlargement of the usually sma...

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...

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 ...

A bifid or forked or bifurcated rib is a congenital skeletal abnormality of the rib cage with the cleaved sternal end into two. They are thought to occur in ~0.2% of the population and there may be a female as well as right-sided predilection 2. Epidemiology Associations Bifid ribs can be see...

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.  Epidemiology A bovine arch is present in ~15% (range 8-25%) of the population and is more common in individuals of Afri...

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). It originates directly from the superior labrum adjacent to the bicipital labral complex and inserts onto the...

Caval variants, the variance of the anatomy of the venae cavae are common,  due to the complex embryology of the venous system. Caval variants are important for a number of reasons: to avoid confusion with venous pathology to suggest the presence of frequently associated abnormalities to plan...

Cavum septum pellucidum (CSP) is a normal variant CSF space between the leaflets of the septum pellucidum. Terminology While the term "cavum septum pellucidum" is generally accepted, it is grammatically incorrect. Since it denotes a space (cavum meaning cave) of the septum pellucidum, the seco...

The cavum vergae (CV), along with the cavum septum pellucidum (CSP) that lies immediately anterior to it, is a persistence of the embryological fluid-filled space between the leaflets of the septum pellucidum and is a common anatomical variant.  Terminology The cavum vergae has also been refer...

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 menisci are anatomical variants 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, altho...

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 the site of the aortic isthmus, where the ligamentum arteriosum attaches. It is also the...

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...

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 pseudo-SLAP lesion

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, 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...

An os supratalare is an accessory ossicle of the foot located at the superior aspect of the talar head or neck. Epidemiology It's a rare variant with a reported incidence of ~1% (range 0.2-2.4%) 1. Clinical presentation It is almost always asymptomatic although some cases reported dorsal hin...

An accessory navicular 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 asymptomatic but in a small proportion, it may cause painful tendinosis ...

The exocrine pancreas drains into the gastrointestinal tract via the main and accessory pancreatic ducts. Several anatomical variations of the typical ductal drainage pattern exist, reflecting variations in the embryological development and fusion of the dorsal and ventral pancreatic buds 13,14....

The ossiculum terminale appears as a secondary ossification center of the dens between 3-6 years and normally fuses by 12 years. Failure of fusion results in a persistent ossiculum terminale (also called Bergmann's ossicle or ossiculum terminale of Bergmann) and is considered a normal anatomical...