| fissure bur | A cylindrical or tapered rotary cutting tool intended for extending or widening fissures in a tooth, as for general surface reduction of tooth substance. (05 Mar 2000) |
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| fissure caries | Caries beginning in a fissure on the occlusal surfaces of posterior teeth. (05 Mar 2000) |
| fissure for ligamentum teres | A cleft on the inferior surface of the liver, running from the inferior border to the left extremity of the porta hepatis; it lodges the round ligament of the liver. Synonym: fissura ligamenti teretis, fissure for ligamentum teres, fossa venae umbilicalis, umbilical fissure, umbilical fossa. (05 Mar 2000) |
| fissure in ano | A painful linear ulcer at the margin of the anus. It appears as a crack or slit in the mucous membrane of the anus and is very painful and difficult to heal. (12 Dec 1998) |
| fissure of ligamentum venosum | A deep cleft extending from the porta hepatis and the inferior vena cava between the left lobe and the caudate lobe; it lodges the ligamentum venosum and is thus a vestige of the fossa of the ductus venosus. Synonym: fissura ligamenti venosi, fissure of venous ligament. (05 Mar 2000) |
| fissure of Rolando | A double-S-shaped fissure extending obliquely upward and backward on the lateral surface of each cerebral hemisphere at the boundary between frontal and parietal lobes. Synonym: sulcus centralis, fissure of Rolando. (05 Mar 2000) |
| fissure sealant | A dental material usually made from interaction between bisphenol A and glycidyl methacrylate; such sealant's are used to seal nonfused, noncarious pits and fissures on surfaces of teeth. Synonym: dental sealant. (05 Mar 2000) |
| fissure sign | In perfusion scintigraphy of the lungs, decreased uptake of radionuclide in the periphery of each lobe, making the fissures visible; caused by a variety of diseases and artifacts. (05 Mar 2000) |
| lateral cerebral fissure | The deepest and most prominent of the cortical fissures, extending from the anterior perforated substance first laterally at the deep incisure between the frontal and temporal lobes, then back and slightly upward over the lateral aspect of the cerebral hemisphere, with the superior temporal gyrus as its lower bank, the insula forming its greatly expanded floor. Two short side branches, the ramus anterior and ramus ascendens, divide the inferior frontal gyrus into an orbital part, triangular part, and opercular part. Synonym: sulcus lateralis cerebri, fissura cerebri lateralis, lateral cerebral fissure, sylvian fissure, fissure of Sylvius. (05 Mar 2000) |
| left sagittal fissure | A sagittal groove on the undersurface of the liver formed by the fissura ligamenti teretis anteriorly and the fissura ligamenti venosi posteriorly. (05 Mar 2000) |
| linguogingival fissure | A fissure sometimes occurring on the lingual surface of one of the upper incisors and extending into the cementum. (05 Mar 2000) |
| longitudinal fissure of cerebrum | The deep cleft separating the two hemispheres of the cerebrum. Synonym: fissura longitudinalis cerebri, great longitudinal fissure. (05 Mar 2000) |
| lunate fissure | A small, inconstant semilunar groove on the cortical convexity near the occipital pole, marking the anterior border of the striate cortex (area 17) and considered homologous with the major sulcus of the same name that is a more constant feature of the cerebral cortex in monkeys and apes. Synonym: sulcus lunatus cerebri, ape fissure, lunate fissure, lunate sulcus, simian fissure. (05 Mar 2000) |
| acute yellow atrophy of the liver | A lesion in which there is extensive and rapid death of parenchymal cells of the liver, sometimes with fatty degeneration of the size of the organ; the necrosis may result from fulminant viral infection or chemical poisoning; associated with jaundice. Synonym: acute parenchymatous hepatitis, Rokitansky's disease. (05 Mar 2000) |
| adenoma, liver cell | A benign epithelial tumour of the liver. (12 Dec 1998) |