Items tagged “refs”

2,942 results found
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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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Hilgenreiner line

The Hilgenreiner line (also known as Y-line 2 or teardrop line 3) is a line drawn horizontally through the inferior aspect of both triradiate cartilages. It should be horizontal but is mainly used as a reference for the Perkin line and measurement of the acetabular angle. This line with the oth...
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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...
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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...
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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
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Fisher scale

The Fisher scale is the initial and best known system of classifying the amount of subarachnoid hemorrhage on CT scans, and is useful in predicting the occurrence and severity of cerebral vasospasm, highest in grade 3 2.  Numerous other scales have been proposed, incorporating various parameter...
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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 mucosa and muscularis whereas the submucosa is responsible fo the hypoechoi...
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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...
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External auditory canal exostoses

Exostosis of the external auditory canal (also known as surfer's ear), is a benign bony overgrowth of the bony external auditory canal brought about by exposure to cold wind and water combined. Epidemiology The estimated prevalence in cold water surfers is thought to range between 70-80% 5,6. ...
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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...
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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 ...
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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...
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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 ...
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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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Lucent/lytic bone lesion - differential diagnosis (mnemonic)

Mnemonics for the differential diagnosis of lucent/lytic bone lesions include: FEGNOMASHIC FOG MACHINES They are anagrams of each other and therefore include the same components. They are by no means exhaustive lists, but are a good start for remembering a differential for a lucent/lytic bone...
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Internal acoustic canal

The internal acoustic canal (IAC), also known as the internal auditory canal or meatus (IAM), is a bony canal within the petrous portion of the temporal bone that transmits nerves and vessels from within the posterior cranial fossa to the auditory and vestibular apparatus. Gross anatomy The op...
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Falciform crest

The falciform crest, also known as the crista falciformis, is a horizontal bony ridge that divides the lateral portion of the internal acoustic meatus (IAM) into superior and inferior portions. Superior The facial nerve (VII) and superior vestibular nerve (SVN) travel in the superior portion o...
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Diencephalon

The diencephalon is connected above and in front of the cerebral hemispheres; behind the mid-brain. Its upper surface is concealed by the corpus callosum, and is covered by a fold of pia mater, named the tela choroidea of the third ventricle; inferiorly it reaches to the base of the brain. It c...