| spiral canal of cochlea | The winding tube of the bony labyrinth which makes two and a half turns about the modiolus of the cochlea; it is divided incompletely into two compartments by a winding shelf of bone, the bony spiral lamina. Synonym: canalis spiralis cochleae, Rosenthal's canal, spiral canal of cochlea. (05 Mar 2000) |
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| spiral canal of modiolus | <anatomy> The space in the modiolus in which the spiral ganglion of the cochlear nerve lies. Synonym: canalis spiralis modioli. (05 Mar 2000) |
| spiral cleavage | <marine biology> Pattern of early cleavage found in molluscs and annelids (both mosaic eggs). The animal pole blastomeres are rotated with respect to those of the vegetal pole. The handedness of the spiral twist is maternally inherited. (18 Nov 1997) |
| spiral cochlear ganglion | An elongated ganglion of bipolar sensory nerve cell bodies on the cochlear part of the vestibulocochlear nerve in the spiral canal of the modiolus; each ganglion cell gives rise to a peripheral process that passes between the layers of the bony spiral lamina to the organ of Corti, and a central axon that enters the hindbrain as a component of the inferior (cochlear) root of the eighth nerve. Synonym: ganglion spirale cochleae, auditory ganglion, cochlear ganglion, Corti's ganglion, spiral cochlear ganglion. (05 Mar 2000) |
| spiral computed tomography | <radiology> Computed tomography in which the X-ray tube continuously revolves around the patient, who is simultaneously moved longitudinally; computer interpolation allows reconstruction of standard transverse scans or images in any preferred plane. Synonym: helical computed tomography, helical CT, spiral CT. (20 Jun 2000) |
| spiral crest | The thickened periosteal lining of the bony cochlea forming the outer wall of the cochlear duct to which the basal lamina attaches. Synonym: crista spiralis, ligamentum spirale cochleae, spiral crest. (05 Mar 2000) |
| spiral CT | <radiology> Computed tomography in which the X-ray tube continuously revolves around the patient, who is simultaneously moved longitudinally; computer interpolation allows reconstruction of standard transverse scans or images in any preferred plane. Synonym: helical computed tomography, helical CT, spiral CT. (20 Jun 2000) |
| spiral fold of cystic duct | A series of crescentic folds of mucous membrane in the upper part of the cystic duct, arranged in a somewhat spiral manner. Synonym: plica spiralis ductus cystici, Amussat's valve, Heister's valve, spiral valve of cystic duct, valvula spiralis. (05 Mar 2000) |
| spiral foraminous tract | Openings in the cochlear area of the bottom of the internal acoustic meatus through which the fibres of the cochlear nerve leave the bony labyrinth to enter the cranial cavity. Synonym: tractus spiralis foraminosus. (05 Mar 2000) |
| spiral fracture | A fracture the line of which is helical in the bone. (05 Mar 2000) |
| spiral ganglion | The sensory ganglion of the cochlear nerve. The cells of the spiral ganglion send fibres peripherally to the cochlear hair cells and centrally to the cochlear nuclei of the brainstem. (12 Dec 1998) |
| spiral ganglion of cochlea | An elongated ganglion of bipolar sensory nerve cell bodies on the cochlear part of the vestibulocochlear nerve in the spiral canal of the modiolus; each ganglion cell gives rise to a peripheral process that passes between the layers of the bony spiral lamina to the organ of Corti, and a central axon that enters the hindbrain as a component of the inferior (cochlear) root of the eighth nerve. Synonym: ganglion spirale cochleae, auditory ganglion, cochlear ganglion, Corti's ganglion, spiral cochlear ganglion. (05 Mar 2000) |
| spiral groove | <anatomy, nerve> The shallow groove that passes around the shaft of the humerus; it lodges the radial nerve and deep brachial artery. Synonym: sulcus nervi radialis, musculospiral groove, spiral groove. (05 Mar 2000) |
| spiral hyphae | Hyphae that end in a flat or helical coil, as in laboratory colonies of Trichophyton mentagrophytes. (05 Mar 2000) |
| spiral joint | A variety of hinge joint in which the elevation and depression, respectively, on the opposing articular surfaces form part of a spiral, flexion being then accompanied by a certain amount of lateral deviation. Synonym: screw joint, spiral joint. (05 Mar 2000) |