- 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. [L. fr. G. gyros, circle]- angular g. [TA] a folded convolution in the inferior parietal lobule formed by the union of the posterior ends of the superior and middle temporal gyri; a g. located around the caudal terminus of the superior temporal sulcus. SYN: g. angularis [TA], angular convolution.- g. angularis [TA] SYN: angular g..- annectent g. SYN: transitional g..- anterior central g. SYN: precentral g..- anterior paracentral g. [TA] the anterior portion of the paracentral lobule; the medial continuation of the primary somatomotor cortex (precentral g.) in which the thigh, leg, and foot are represented. SYN: g. paracentralis anterior [TA].- anterior transverse temporal g. [TA] See transverse temporal gyri. SYN: g. temporalis transversus anterior [TA].- ascending frontal g. SYN: precentral g..- ascending parietal g. SYN: postcentral g..- gyri breves insulae [TA] SYN: short gyri of insula.- cerebral gyri [TA] SYN: gyri cerebri.- cingulate g. [TA] a long, curved convolution of the medial surface of the cortical hemisphere, arched over the corpus callosum from which it is separated by the deep sulcus of corpus callosum; together with the parahippocampal g., with which it is continuous behind the corpus callosum, it forms the fornicate g.. SYN: g. cinguli [TA], callosal convolution, callosal g., cingulate convolution, falciform lobe, lobus falciformis.- g. cinguli [TA] SYN: cingulate g..- deep transitional g. the transverse g. of the embryo which in development becomes buried in the depth of the central sulcus of the cerebral hemisphere.- dentate g. [TA] one of the two interlocking gyri composing the hippocampus, the other one being the Ammon horn. SYN: g. dentatus [TA], dentate fascia, fascia dentata hippocampi.- g. dentatus [TA] SYN: dentate g..- fasciolar g. [TA] a small paired band that passes around the splenium of the corpus callosum from the lateral longitudinal stria to the dentate g.. SYN: g. fasciolaris [TA], fascia cinerea, fasciola cinerea.- g. fasciolaris [TA] SYN: fasciolar g..- fornicate g. the horseshoe-shaped cortical convolution bordering the hilus of the cerebral hemisphere; its upper limb is formed by the cingulate g., its lower by the parahippocampal g.; SYN: g. fornicatus (1).- fusiform g. an extremely long convolution extending lengthwise over the inferior aspect of the temporal and occipital lobes, demarcated medially by the collateral sulcus from the lingual g. and the anterior part of the parahippocampal g., laterally by the inferior temporal sulcus from the inferior temporal g.. SYN: g. occipitotemporalis lateralis [TA], lateral occipitotemporal g. [TA], g. fusiformis, lobulus fusiformis.- g. fusiformis SYN: fusiform g..- hippocampal g. SYN: parahippocampal g..- inferior frontal g. [TA] a broad convolution on the convexity of the frontal lobe of the cerebrum between the inferior frontal sulcus and the sylvian fissure; divided by branches of the sylvian fissure into three parts: opercular part [TA] (pars opercularis [TA]), triangular part [TA] (pars triangularis [TA]), and orbital part [TA] (pars orbitalis [TA]); the first two constitute a portion of the frontal operculum. SYN: g. frontalis inferior [TA], inferior frontal convolution.- inferior occipital g. a g. situated below the lateral occipital sulcus on the lower part of the lateral surface of the occipital lobe.- inferior temporal g. [TA] a sagittal convolution on the inferolateral border of the temporal lobe of the cerebrum, separated from the middle temporal g. by the inferior temporal sulcus. On the inferior surface of the temporal lobe it is separated from the medial occipitotemporal g. by the occipitotemporal sulcus. It includes the lateral occipitotemporal g.. SYN: g. temporalis inferior [TA], inferior temporal convolution, third temporal convolution.- gyri insulae [TA] SYN: insular gyri.- interlocking gyri several small gyri in the walls of the central sulcus of the hemisphere; the opposed gyri interlock with one another.- lateral olfactory g. [TA] superficial layers of cells located adjacent to the lateral olfactory stria; poorly developed in microsmatic animals but well developed in macrosmatic animals. SYN: g. olfactorius lateralis [TA].- lingual g. [TA] a relatively short horizontal convolution on the inferomedial aspect of the occipital and temporal lobes, demarcated from the lateral occipitotemporal or fusiform g. by the deep collateral sulcus, from the cuneus by the calcarine sulcus; its anterior extreme abuts the isthmus of the parahippocampal g.; the medial or upper strip of the g. 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. SYN: g. lingualis [TA], g. occipitotemporalis medialis [TA], medial occipitotemporal g. [TA].- g. lingualis [TA] SYN: lingual g..- long g. of insula [TA] the most posterior and longest of the slender straight gyri that compose the insula. SYN: g. longus insulae [TA].- g. longus insulae [TA] SYN: long g. of insula.- medial frontal g. [TA] term sometimes used to designate the part of the superior frontal g. that wraps over, and is located on, the medial surface of the frontal lobe. SYN: g. frontalis medialis [TA].- medial olfactory g. [TA] layers of cells located adjacent to the medial olfactory stria; well developed in macrosmatic animals but poorly developed in microsmatic animals. SYN: g. olfactorius medialis [TA].- middle frontal g. a convolution on the convexity of each frontal lobe of the cerebrum running in an anteroposterior direction between the superior and inferior frontal sulci. SYN: g. frontalis medius [TA], middle frontal convolution.- middle temporal g. [TA] a longitudinal g. on the lateral surface of the temporal lobe, between the superior and inferior temporal sulci. SYN: g. temporalis medius [TA], middle temporal convolution, second temporal convolution.- orbital gyri [TA] a number of small, irregular convolutions occupying the concave inferior surface of each frontal lobe of the cerebrum. SYN: gyri orbitales [TA].- gyri orbitales [TA] SYN: orbital gyri.- parahippocampal g. [TA] a long convolution on the medial surface of the temporal lobe, forming the lower part of the fornicate g., extending from behind the splenium corporis callosi forward along the dentate g. of the hippocampus from which it is demarcated by the hippocampal fissure. The anterior extreme of the g. curves back upon itself, forming the uncus, the major location of the olfactory cortex. SEE ALSO: entorhinal area. SYN: g. parahippocampalis [TA], hippocampal convolution, hippocampal g..- g. parahippocampalis [TA] SYN: parahippocampal g..- paraterminal g. [TA] SYN: subcallosal g..- g. paraterminalis [TA] SYN: subcallosal g..- postcentral g. [TA] the anterior convolution of the parietal lobe, bounded in front by the central sulcus (fissure of Rolando) and posteriorly by the interparietal sulcus. SYN: g. postcentralis [TA], ascending parietal convolution, ascending parietal g., posterior central convolution, posterior central g..- g. postcentralis [TA] SYN: postcentral g..- posterior central g. SYN: postcentral g..- posterior paracentral g. [TA] the posterior part of the paracentral lobule; the medial continuation of the primary somatosensory cortex (postcentral g.) in which sensory input from the thigh, leg, and foot are represented. SYN: g. paracentralis posterior [TA].- posterior transverse temporal g. [TA] posterior portion of the primary auditory cortex when two gyri are present. SEE ALSO: transverse temporal gyri. SYN: g. temporalis transversus posterior [TA].- precentral g. [TA] bounded posteriorly by the central sulcus and anteriorly by the precentral sulcus. SYN: g. precentralis [TA], anterior central convolution, anterior central g., ascending frontal convolution, ascending frontal g..- g. precentralis [TA] SYN: precentral g..- prepiriform g. a g. covering deeply placed amygdaloid nucleus; concerned with olfactory function. SYN: anterior piriform g..- g. rectus [TA] SYN: straight g..- short gyri of insula [TA] several short, radiating gyri converging toward the base of the insula, composing approximately the anterior two-thirds of the insular cortex. SYN: gyri breves insulae [TA].- splenial g. the band of cortex on the medial surface of the cerebral hemisphere which passes around the splenium of the corpus callosum, narrowing anteriorly and finally blending with the indusium griseum.- straight g. [TA] a g. running along the medial part of the orbital surface of the frontal lobe of the cerebral hemisphere. It is bounded laterally by the olfactory sulcus. SYN: g. rectus [TA].- subcallosal g. 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. The small ridge of tissue immediately rostral to the lamina terminalis is sometimes designated as a separate part of the subcallosal area and called the paraterminal g. [TA] (g. paraterminalis [TA]). SYN: area subcallosa [TA], g. paraterminalis [TA], g. subcallosus [TA], paraterminal g. [TA], subcallosal area [TA], corpus paraterminale, paraterminal body, peduncle of corpus callosum, pedunculus corporis callosi, precommissural septal area, Zuckerkandl convolution.- g. subcallosus [TA] SYN: subcallosal g..- superior frontal g. [TA] a broad convolution running in an anteroposterior direction on the medial edge of the convex surface and wrapping over onto the medial surface of each frontal lobe. SYN: g. frontalis superior [TA], marginal g., superior frontal convolution.- superior occipital g. a g. lying above the lateral occipital sulcus on the lateral surface of the occipital lobe.- superior temporal g. [TA] a longitudinal g. on the lateral surface of the temporal lobe between the lateral (sylvian) fissure and the superior temporal sulcus. SYN: g. temporalis superior [TA], first temporal convolution, superior temporal convolution.- supracallosal g. SYN: indusium griseum.- supramarginal g. [TA] a folded convolution capping the posterior extremity of the lateral (sylvian) sulcus; together with the angular g., it forms the inferior parietal lobule. SYN: g. supramarginalis [TA], supramarginal convolution.- g. supramarginalis [TA] SYN: supramarginal g..- gyri temporales transversi [TA] SYN: transverse temporal gyri.- g. temporalis transversus anterior [TA] SYN: anterior transverse temporal g.. See transverse temporal gyri.- transitional g. a small convolution connecting two lobes or two main gyri in the depth of a sulcus. SYN: annectent g., transitional convolution.- transverse temporal gyri [TA] two or three convolutions running transversely on the upper surface of the temporal lobe bordering on the lateral (sylvian) fissure, separated from each other by the transverse temporal sulci. SYN: gyri temporales transversi [TA], Heschl gyri, transverse temporal convolutions.
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n. (pl. gyri)a raised convolution of the cerebral cortex, between two sulci (clefts).* * *
gy·rus (jiґrəs) gen. and pl. gyґri [L., from Gr. gyros circle] one of the convolutions of the surface of the cerebral hemispheres caused by infolding of the cortex; see gyri cerebri.Descriptions of gyri are given on TA terms, and include anglicized names of specific gyri.
Medical dictionary. 2011.
