| LAS | laboratory automation system; lateral amyotrophic sclerosis; laxative abuse syndrome; left anterior-... |
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| LASH | left anterior superior hemiblock |
| LSR | lanthanide shift reagent; lecithin/ sphingomyelin ratio; left superior rectus [muscle]; liver/spleen... |
| LSVC | left superior vena cava |
| MSO | management service organization; medial superior olive; medical staff organization |
| frontal veins | The superficial veins draining the frontal cortex and emptying into the superior sagittal sinus. Synonym: supratrochlear veins. (05 Mar 2000) |
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| frontal zone contraction theory | Model proposed to account for the movement of giant amoebae in which cytoplasmic contraction at the front of the leading pseudopod (fountain zone) pulls viscoelastic cytoplasm forward in the centre of the cell and forms a tube of more rigid cytoplasm immediately below the plasma membrane behind the active region. The peripheral contracted cytoplasm relaxes into a weaker gel at the rear and is pulled forward in its turn. Contrasts with the ectoplasmic tube contraction model. (18 Nov 1997) |
| annectent gyrus | A small convolution connecting two lobes or two main gyri in the depth of a sulcus. Synonym: annectent gyrus, transitional convolution. (05 Mar 2000) |
| anterior central gyrus | Bounded posteriorly by the central sulcus and anteriorly by the precentral sulcus. Synonym: gyrus precentralis, anterior central convolution, anterior central gyrus, ascending frontal convolution, ascending frontal gyrus. (05 Mar 2000) |
| anterior piriform gyrus | A gyrus covering deeply placed amygdaloid nucleus; concerned with olfactory function. Synonym: anterior piriform gyrus. (05 Mar 2000) |
| artery of angular gyrus | The last branch of the terminal part of the middle cerebral artery distributed to parts of the temporal parietal and occipital lobes. Synonym: arteria gyri angularis, angular artery. (05 Mar 2000) |
| ascending parietal gyrus | The anterior convolution of the parietal lobe, bounded in front by the central sulcus (fissure of Rolando) and posteriorly by the interparietal sulcus. Synonym: gyrus postcentralis, ascending parietal convolution, ascending parietal gyrus, posterior central convolution, posterior central gyrus. (05 Mar 2000) |
| callosal gyrus | cingulate gyrus |
| vein of olfactory gyrus | A tributary of the basal vein which drains the medial olfactory stria. Synonym: vein of olfactory gyrus. (05 Mar 2000) |
| parahippocampal gyrus | A long convolution on the medial surface of the temporal lobe, forming the lower part of the fornicate gyrus, extending from behind the splenium corporis callosi forward along the dentate gyrus of the hippocampus from which it is demarcated by the hippocampal fissure. The anterior extreme of the gyrus curves back upon itself, forming the uncus, the major location of the olfactory cortex. See: entorhinal area. Synonym: gyrus parahippocampalis, hippocampal convolution, hippocampal gyrus. (05 Mar 2000) |
| marginal gyrus | A broad convolution running in an anteroposterior direction on the medial edge of the convex surface and of each frontal lobe. Synonym: gyrus frontalis superior, marginal gyrus, superior frontal convolution. (05 Mar 2000) |
| paraterminal gyrus | A slender vertical whitish band immediately anterior to the lamina terminalis and anterior commissure; contrary to its name, it is not a cortical convolution but is the ventral continuation of the transparent septum. Synonym: area subcallosa, gyrus paraterminalis, gyrus subcallosus, pedunculus corporis callosi, corpus paraterminale, paraterminal body, paraterminal gyrus, peduncle of corpus callosum, precommissural septal area, subcallosal area, Zuckerkandl's convolution. (05 Mar 2000) |
| medial occipitotemporal gyrus | A relatively short horizontal convolution on the inferomedial aspect of the occipital and temporal lobes, demarcated from the lateral occipitotemporal or fusiform gyrus by the deep collateral sulcus, from the cuneus by the calcarine sulcus; its anterior extreme abuts the isthmus of the parahippocampal gyrus; the medial or upper strip of the gyrus forming the lower bank of the calcarine sulcus corresponds to the inferior half of the striate area or primary visual cortex and represents the contralateral upper quadrant of the binocular field of vision. Synonym: gyrus lingualis, gyrus occipitotemporalis medialis, medial occipitotemporal gyrus. (05 Mar 2000) |
| Retzius' gyrus | The intralimbic gyrus in the cortical portion of the rhinencephalon. (05 Mar 2000) |
| gyrus | One of the prominent rounded elevations that form the cerebral hemispheres, each consisting of an exposed superficial portion and a portion hidden from view in the wall and floor of the sulcus. Origin: L. Fr. G. Gyros, circle Angular gyrus, a folded convolution in the inferior parietal lobule formed by the union of the posterior ends of the superior and middle temporal gyri. Synonym: gyrus angularis, angular convolution. (05 Mar 2000) |