| spiral membrane | The wall that separates the cochlear duct from the scala tympani; it consists of the osseous spiral lamina and the basilar membrane. Synonym: paries tympanicus ductus cochlearis, membrana spiralis, spiral membrane. (05 Mar 2000) |
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| spiral organ | A prominent ridge of highly specialised epithelium in the floor of the cochlear duct overlying the basilar membrane of cochlea, containing one inner row and three outer rows of hair cells, or cells of Corti (the auditory receptor cells innervated by the cochlear nerve) supported by various columnar cells: the pillars of Corti, cells of Hensen, and cells of Claudius; the spiral organ is partly overhung by an awning-like shelf, the tectorial membrane, the free marginal zone of which is covered by a gelatinous substance in which the stereocilia of the outer hair cells are embedded. Synonym: organum spirale, acoustic papilla, Corti's organ. (05 Mar 2000) |
| spiral plate | A double plate of bone winding spirally around the modiolus dividing the spiral canal of the cochlea incompletely into two, scala tympani and scala vestibuli; between the two plates of this lamina the fibres of the cochlear nerve reach the spiral organ (of Corti). Synonym: lamina spiralis ossea, spiral plate. (05 Mar 2000) |
| spiral prominence | A projecting portion of the spiral ligament of the cochlea, bounding the lower edge of the stria vascularis and containing within it a blood vessel, the vas prominens. Synonym: prominentia spiralis. (05 Mar 2000) |
| spiral septum | A septum dividing the embryonic bulbus cordis into pulmonary and aortic outflow tracts from the developing heart; the distal spiral septum is derived from the right and left endocardial cushions and so separates the pulmonary and aortic orifices; the proximal spiral septum is the portion of the septum that is incorporated into the membranous part of the interventricular septum. (05 Mar 2000) |
| spiral suture | An uninterrupted series of stitches using one suture; the stitching is fastened at each end by a knot. Synonym: spiral suture, uninterrupted suture. (05 Mar 2000) |
| spiral tip catheter | A catheter with a helical filiform tip. (05 Mar 2000) |
| spiral tubule | The segment of urinary tubule coming next after the proximal convoluted tubule. (05 Mar 2000) |
| spiral valve 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 vein of modiolus | The vein running a spiral course in the modiolus of the cochlea; it is tributary to both the labyrinthine vein and the vein of the cochlear canaliculus. Synonym: vena spiralis modioli. (05 Mar 2000) |
| distal spiral septum | See: spiral septum. (05 Mar 2000) |
| osseous spiral lamina | A double plate of bone winding spirally around the modiolus dividing the spiral canal of the cochlea incompletely into two, scala tympani and scala vestibuli; between the two plates of this lamina the fibres of the cochlear nerve reach the spiral organ (of Corti). Synonym: lamina spiralis ossea, spiral plate. (05 Mar 2000) |
| tympanic labium of limbus of spiral lamina | The lower, long periosteal extension of the limbus laminae spiralis osseae that rests on the basilar lamina of the spiral organ (of Corti). Synonym: labium limbi tympanicum laminae spiralis, tympanic lip of limbus of spiral lamina. Labium urethrae, one of the two lateral margins of the external urethral orifice of the female. (05 Mar 2000) |
| tympanic lip of limbus of spiral lamina | The lower, long periosteal extension of the limbus laminae spiralis osseae that rests on the basilar lamina of the spiral organ (of Corti). Synonym: labium limbi tympanicum laminae spiralis, tympanic lip of limbus of spiral lamina. Labium urethrae, one of the two lateral margins of the external urethral orifice of the female. (05 Mar 2000) |
| limbus of bony spiral lamina | The border of the spiral lamina; the thickened periosteum covering the upper plate of the bony spiral lamina of the cochlea. Synonym: limbus laminae spiralis osseae. (05 Mar 2000) |