Items tagged “normal variant”
88 results found
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...
Variant anatomy of the aortic arch
Variant anatomy of the aortic arch occurs when there is failure of normal aortic development. It results in a number of heterogenous anomalies of the aorta and its branch vessels. Gross anatomy Normally, the aorta ascends in the superior mediastinum to the level of the sternal notch before arc...
Os acromiale represents an unfused accessory centre of ossification of the acromion of the scapula. Epidemiology Os acromiale are relatively common, seen in ~8% (range 1-15%) of the population 1,2 and may be bilateral in 60% of individuals 5. Clinical presentation They are usually asymptoma...
Os odontoideum is an anatomic variant of the odontoid process of C2 and needs to be differentiated from persistent ossiculum terminale and from a type 2 odontoid fracture. It can be associated with atlantoaxial instability. Although it was originally thought to be a congenital lesion due to a ...
Persistent carotid-vertebrobasilar anastomoses
The persistent carotid-vertebrobasilar anastomoses are named, with the exception of the proatlantal artery, using the cranial nerves with which they run: persistent trigeminal artery arises from proximal cavernous ICA most common persistent carotid-vertebrobasilar anastomosis two types - lat...
Persistent otic artery
The persistent otic artery is one of the persistent carotid-vertebrobasilar anastomoses, although there is considerable controversy in regards to its existence. It is said to arise from the internal carotid artery within the carotid canal, emerges from the internal acoustic meatus, and joins the...
Persistent hypoglossal artery
A persistent hypoglossal artery is one of the persistent carotid-vertebrobasilar anastomoses. It is second in frequency to the trigeminal artery which is present approximately six times as often. It arises from the distal cervical ICA, usually between C1 and C3. After passing through an enlarg...
Basilar artery fenestration
Basilar artery fenestration (or more simply, basilar fenestration) is the most common intracranial arterial fenestration. It refers to duplication of a portion of the artery. Its reported prevalence is highly variable depending on the technique used: ~0.5% (0.3-0.6%) at angiography (presumably ...
An os peroneum is a small accessory bone located at the lateral plantar aspect of the cuboid within the substance of the peroneus longus tendon as it arches around the cuboid. It is very common, seen in up to 26% of feet 1. Differential diagnosis It should not be mistaken for: os vesalianum ...
Supracondylar process of humerus
Published 18 Mar 2010
Developmental anomalies of the kidney and ureter
Developmental anomalies of the kidneys and ureters are numerous and not only potentially render image interpretation confusing but also, in many instances, make the kidneys more prone to pathology: number renal agenesis supernumerary kidney fusion horseshoe kidney: most common cross fused ...
Replaced left and right hepatic arteries
Published 15 Jun 2010
Os trigonum is one of the bony ossicles of the foot and can be mistaken for a fracture. It sits posterior to the talus on the lateral foot radiograph and represents a failure of fusion of the lateral tubercle of the posterior process. It is estimated to be present in ~7% of adults 1. The ossic...
Published 02 Aug 2010
Diagnosis not applicable
Published 15 Aug 2010
Os calcaneus secundarius
An os calcaneus secundarius is an accessory ossicle of the anterior calcaneal process present in up to 5% of the population at cadaveric examination. The ossicle can be a cause of ankle pain and may mimic bifurcated ligament avulsion fracture of the anterior calcaneal process. Differential diag...
A patent urachus is one of the spectrum of congenital urachal anomalies. It has occasionally been termed "urachal fistula". Clinical presentation A patent urachus is often diagnosed in neonates when urine is noted leaking from the umbilicus. The umbilicus may also have an abnormal appearance o...
A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center at the superolateral aspect. Epidemiology The superolateral accessory ossification center of the patella is usually present by 12 years of age and may persist into adult life. Prevalence of a bipa...
Published 02 Nov 2010
Synovial herniation pit
Diagnosis almost certain
Published 10 Nov 2010