Items tagged “normal variant”
33 results found
Article
Aberrant right subclavian artery
Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are among the commonest aortic arch anomalies.
Epidemiology
The estimated incidence is 0.5-2% 1.
Associations
as can be expected from the embryological development of the artery, the right recurrent laryngeal nerve...
Article
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...
Article
Os acromiale
Os acromiale is an anatomical variant and represents an unfused accessory center of ossification of the acromion of the scapula.
Epidemiology
Os acromiale is relatively common, seen in ~8% (range 1-15%) of the population 1,2 and can be bilateral in 60% of individuals 5.
Clinical presentation
...
Article
Os odontoideum
Os odontoideum (plural: ossa odontoidea) 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 c...
Article
Persistent carotid-vertebrobasilar anastomoses
The persistent carotid-vertebrobasilar anastomoses are variant anatomical arterial communications between the anterior and posterior circulations due to abnormal embryological development of the vertebrobasilar system. They are named, with the exception of the proatlantal artery, using the crani...
Article
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 C2 (petrous) segment of the internal carotid artery within the carotid canal. This artery emerges from the...
Article
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 segment, usually between the C1 and C3 vertebral level. Aft...
Article
Basilar artery fenestration
Basilar artery fenestration (or more simply, basilar fenestration) is the most common intracranial arterial fenestration and most common congenital anomaly of the basilar artery. This anatomic variant is characterized by duplication of a portion of the artery that are connected proximally and di...
Article
Os peroneum
An os peroneum is a small accessory bone of the foot located at the lateral aspect of the cuboid within the substance of the fibularis longus tendon as it arches around the cuboid.
Epidemiology
It is a very common anatomical variant, seen in up to 26% of feet 1.
Differential diagnosis
It sho...
Article
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 ...
Article
Os trigonum
The os trigonum (plural: ossa trigona) is one of the 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% ...
Article
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 bifurcate ligament avulsion fracture of the anterior calcaneal process.
Differential diagn...
Article
Patent urachus
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...
Article
Bipartite patella
A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center, typically 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. Bipartite...
Article
Anconeus epitrochlearis muscle
The anconeus epitrochlearis muscle is an accessory muscle of the upper limb at the medial aspect of the elbow. It is also known as the accessory anconeus muscle or epitrochleoanconeus muscle and should not be confused with the anconeus muscle which is present at the lateral aspect of the elbow. ...
Article
Junctional parenchymal defect of kidney
Junctional parenchymal defects in renal imaging are a normal variant, which results from the incomplete embryonic fusion of renunculi.
Radiographic features
Ultrasound
It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. The defect is the extensi...
Article
Arcuate foramen
The arcuate foramen (foramen arcuate atlantis, ponticulus posticus or posterior ponticle, or Kimerle anomaly) is a frequently encountered normal variant of the atlas and is easily appreciated on a lateral plain film of the craniocervical junction.
Epidemiology
Incidence is ~8% (range 1-15%) an...
Article
Accessory ossicles of the foot
Accessory ossicles of the feet are common developmental variants with almost 40 having been described. Some of the more common include 1-4:
os peroneum
os subfibulare
os subtibiale
os tibiale externum (accessory navicular)
os trigonum
os calcaneus secundaris
os calcanei accessorium 6
os ...
Article
Multipartite patella
Multipartite patella is an uncommon congenital abnormality that represents normal variant pathology and is a result of a failure of ossification during development. It is most commonly diagnosed as an incidental finding.
Clinical presentation
The vast majority of multipartite patellae are asy...
Article
Os subtibiale
An os subtibiale is a rare, genuine accessory ossicle and normal variant related to the posterior colliculus of the medial malleolus 1. It is present in ~1% of the population 5.
Clinical presentation
They usually are asymptomatic although they may eventually cause painful syndromes or degener...
Unable to process the form. Check for errors and try again.