| frontal suture | The suture between the two halves of the frontal bone, usually obliterated by about the sixth year; if persistent it is called a metropic suture. Synonym: sutura frontalis. (05 Mar 2000) |
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| frontal triangle | A triangle bounded above by the maximum frontal diameter and laterally by lines joining the extremities of this diameter with the glabella. (05 Mar 2000) |
| frontal tuber | The most prominent portion of the frontal bone on either side. Synonym: tuber frontale, eminentia frontalis, frontal tuber. (05 Mar 2000) |
| frontal veins | The superficial veins draining the frontal cortex and emptying into the superior sagittal sinus. Synonym: supratrochlear veins. (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) |
| 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) |