Items tagged “refs”
2,967 results found
Article
Vertebral anomalies
The vertebral column is affected by a range of anatomical variants of the body and/or neural arch as well as accessory ossicles. Knowledge of basic vertebral anatomy and ossification is essential for describing and understanding the range of anomalies.
Variant anatomy
Vertebral body
hemiverte...
Article
Vestibulocochlear nerve
The vestibulocochlear nerve is the eighth (CN VIII) cranial nerve (TA: nervus vestibulocochlearis or nervus cranialis VIII). It exits the brainstem through the cerebellopontine angle, passing into the internal acoustic meatus as part of the acousticofacial bundle. Within the internal acoustic me...
Article
Vidian nerve
Vidian nerve, also known as the nerve of the pterygoid canal or nerve of the Vidian canal, is so named because of the canal in which it travels: the Vidian canal.
It is formed by the confluence of two nerves:
greater superficial petrosal nerve (from the geniculate ganglion of nervus intermediu...
Article
Vitamin A
Vitamin A are a group of fat-soluble vitamers (the retinoids) required for many physiological functions, mainly vision, reproduction and epithelial maintenance. In the retina, a specific retinoid, 11-cis-retinal, is formed by photoisomerisation within the rods and cones. The retinoids are hemati...
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WHO classification of odontogenic and maxillofacial bone tumors
The WHO classification of odontogenic and maxillofacial bone tumors, last published in 2017, is a subset of the WHO classification of head and neck tumors (4th edition), which lays out a histological classification system for neoplasms and other tumors related to the odontogenic apparatus.
Clas...
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Hilgenreiner line
The Hilgenreiner line (also known as Y-line 2 or teardrop line 3) is a line drawn horizontally through the inferior portion of the iliac bones at the triradiate cartilages. This equates to drawing a line through the triradiate cartilages and pushing it cranially until it touches the iliac bone o...
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Alpha angle (developmental dysplasia of the hip)
The alpha angle is a measurement used in the ultrasonographic assessment of developmental dysplasia of the hip (DDH).
Terminology
The term alpha angle is also used in a separate and unrelated context in the evaluation of femoroacetabular impingement.
Measurement
The angle is formed by the ac...
Article
Hypothalamus
The hypothalamus (plural: hypothalami) is located, as the name would suggest, below the thalamus, and is intimately associated with both the limbic system and the pituitary gland.
Gross anatomy
Boundaries
Its boundaries are in some places poorly defined (outlined in blue in Figure 2):
anter...
Article
Ependymal cyst
Ependymal cysts are rare benign neuroepithelial cysts lined by ependymal cells. Most are small and asymptomatic and only cause symptoms if large.
On imaging, these cysts are essentially indistinguishable from other intraventricular simple cysts (e.g. intraventricular arachnoid cysts).
Epidemio...
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Thoracic aortic dilatation (differential)
There is a broad differential for thoracic aortic dilatation.
Differential diagnosis
senile ectasia
hypertension
post-stenotic dilatation, e.g. bicuspid aortic valve
thoracic aortic aneurysm
atherosclerosis (usually descending thoracic aorta)
collagen disorders
Marfa...
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Thoracic aortic stenosis (differential)
The differential for thoracic aortic stenosis includes:
atherosclerosis
aortitis (especially Takayasu arteritis)
radiotherapy
coarctation
pseudocoarctation
Williams syndrome: supravalvular aortic stenosis
congenital rubella syndrome: supravalvular aortic stenosis
Article
Fisher scale
The Fisher scale is the initial and best-known system of classifying the amount of subarachnoid hemorrhage on CT scans, described in 1980 4. Its primary use was in predicting the occurrence and severity of cerebral vasospasm, highest in grade 3 2,4.
Usage
Although it is known as a scale, fro...
Article
Target sign (intussusception)
The target sign of intestinal intussusception, also known as the doughnut sign or bull's eye sign.
The appearance is generated by concentric alternating echogenic and hypoechoic bands. The echogenic bands are formed by the serosa and submucosa either side of the hypoechoic muscularis propria 1....
Article
Gerstmann syndrome
Gerstmann syndrome, also known as angular gyrus syndrome, is a dominant hemisphere stroke syndrome affecting the left parietal lobe in the region of the angular gyrus, consisting of four components:
agraphia or dysgraphia
acalculia or dyscalculia
finger agnosia
left-right disorientation
Pu...
Article
Neoplasms of the spinal canal
Neoplasms of the spinal canal encompass a range of tumors which arise from or involve the spinal cord, theca, and spinal nerves.
Pathology
These can be divided according to the tissue/structure of origin within the spinal canal. Tumors of vertebral bodies are discussed separately: see vertebra...
Article
Facial colliculus syndrome
Facial colliculus syndrome refers to a constellation of neurological signs due to a lesion at the facial colliculus, involving:
abducens nerve (CN VI) nucleus
facial nerve (CN VII) fibers at the genu
medial longitudinal fasciculus
Clinical presentation
lower motor neuron facial nerve palsy ...
Article
Toxic leukoencephalopathy
Toxic leukoencephalopathy is an encephalopathy predominantly affecting white matter as a result of a toxic substance. The presentation can either be chronic or acute. In the acute phase, acute toxic leukoencephalopathy can have a characteristic and profound MR imaging appearance that is potentia...
Article
Heroin-induced leukoencephalopathy
Heroin-induced leukoencephalopathy, also known as heroin-associated spongiform leukoencephalopathy, is a toxic leukoencephalopathy caused by the inhalation of heroin fumes, which is called "chasing the dragon."
Clinical presentation
Three stages are recognized:
cerebellar signs and motor rest...
Article
Empty delta sign (dural venous sinus thrombosis)
The empty delta sign is a CT sign of dural venous sinus thrombosis of the superior sagittal sinus, where contrast outlines a triangular filling defect, which represents thrombus. It is only described in contrast-enhanced CT, not in unenhanced scans.
An equivalent appearance can be noted in the ...
Article
Couinaud classification of hepatic segments
The Couinaud classification (French eponym: pronounced kwee-NO) is currently the most widely used system to describe functional liver anatomy. It is the preferred anatomy classification system as it divides the liver into eight independent functional units (termed segments) rather than relying o...
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