| language zone | A large area of the cerebral cortex on the left side (in right-handed persons) considered by some to embrace all the centres of memories and associations connected with language. (05 Mar 2000) |
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| latent zone | That portion of the cerebral cortex, the stimulation of which produces no movement and a lesion of which produces no symptoms; mainly the more anterior areas of the frontal lobes. (05 Mar 2000) |
| 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) |
| Lissauer's marginal zone | A longitudinal bundle of thin, unmyelinated and poorly myelinated fibres capping the apex of the posterior horn of the spinal gray matter, composed of posterior root fibres and short association fibres that interconnect neighboring segments of the posterior horn. Synonym: fasciculus dorsolateralis, tractus dorsolateralis, dorsolateral tract, fasciculus marginalis, Lissauer's bundle, Lissauer's column, Lissauer's fasciculus, Lissauer's marginal zone, Lissauer's tract, marginal fasciculus, Spitzka's marginal tract, Spitzka's marginal zone, Waldeyer's tract, Waldeyer's zonal layer. (05 Mar 2000) |
| acoustic crest | An elevation on the inner surface of the ampulla of each saemicircular duct; filaments of the vestibular nerve pass through the crista to reach hair cells on its surface; the hair cells are capped by the cupula, a gelatinous protein-polysaccharide mass. Synonym: crista ampullaris, acoustic crest, transverse septum. (05 Mar 2000) |
| acousticofacial crest | The part of the neural crest from which the ganglia of the seventh and eighth cranial nerves develop. (05 Mar 2000) |
| alveolar crest | The portion of the alveolar bone extending beyond the periphery of the socket, lying interproximally, the top of the residual alveolar bone. (05 Mar 2000) |
| ampullary crest | An elevation on the inner surface of the ampulla of each saemicircular duct; filaments of the vestibular nerve pass through the crista to reach hair cells on its surface; the hair cells are capped by the cupula, a gelatinous protein-polysaccharide mass. Synonym: crista ampullaris, acoustic crest, transverse septum. (05 Mar 2000) |
| anterior lacrimal crest | A vertical ridge on the lateral surface of the frontal process of the maxilla that forms part of the medial rim of the orbit. Synonym: crista lacrimalis anterior. (05 Mar 2000) |
| arched crest | The ridge on the anterior surface of the arytenoid cartilage that separates the triangular from the oblong fovea. Synonym: crista arcuata cartilaginis arytenoideae, arched crest, arcuate crest. (05 Mar 2000) |
| arcuate crest | The ridge on the anterior surface of the arytenoid cartilage that separates the triangular from the oblong fovea. Synonym: crista arcuata cartilaginis arytenoideae, arched crest, arcuate crest. (05 Mar 2000) |
| arcuate crest of arytenoid cartilage | The ridge on the anterior surface of the arytenoid cartilage that separates the triangular from the oblong fovea. Synonym: crista arcuata cartilaginis arytenoideae, arched crest, arcuate crest. (05 Mar 2000) |
| basilar crest of cochlear duct | An inward projection of the spiral ligament of the cochlea to which is attached the basilar membrane forming the floor of the cochlear duct. Synonym: crista basilaris ductus cochlearis. (05 Mar 2000) |
| buccinator crest | A ridge passing from the base of the coronoid process of the mandible to the region of the last molar tooth; it gives attachment to the mandibular part of the buccinator muscle. Synonym: crista buccinatoria. (05 Mar 2000) |
| cap of the ampullary crest | A gelatinous mass that overlies the hair cells of the ampullary crests of the saemicircular ducts; movement of endolymphatic fluid causes the cupula to move across the hair cells of the ampullary crest. Synonym: cap of the ampullary crest. (05 Mar 2000) |