. Cunningham's Text-book of anatomy. Anatomy. DUCTUS COCHLEAEIS. 849 Outer attachment of the membrana vestibularis the apex of the latter its upper extremity, the lagena, or caecum capulare, is fixed to the cupula and partly bounds the helicotrema. As already stated, the membrana basilaris extends from the free edge of the lamina spiralis ossea to the outer wall of the cochlea. A second, more delicate membrane, the membrana vestibularis ( membrane of Reissner), stretches from the thickened periosteum covering the upper surface of the lamina spiralis ossea to the outer cochlear wall, some l
. Cunningham's Text-book of anatomy. Anatomy. DUCTUS COCHLEAEIS. 849 Outer attachment of the membrana vestibularis the apex of the latter its upper extremity, the lagena, or caecum capulare, is fixed to the cupula and partly bounds the helicotrema. As already stated, the membrana basilaris extends from the free edge of the lamina spiralis ossea to the outer wall of the cochlea. A second, more delicate membrane, the membrana vestibularis ( membrane of Reissner), stretches from the thickened periosteum covering the upper surface of the lamina spiralis ossea to the outer cochlear wall, some little distance above the external attachment of the membrana basilaris. A canal is thus enclosed between the underlying scala tympani and the overlying scala vestibuli, and constitutes the ductus cochlearis. Triangular on transverse section, the duct possesses a roof, an outer wall, and a floor, and is lined throughout with epithelium and filled with endolymph. On its floor the epithelium is greatly modified, and here are found the endings of the cochlear nerve. The roof or vestibular wall of the ductus cochlearis is formed by the mem- brana vestibularis, a delicate, nearly homogeneous membrane, covered on each surface by a layer of epithelium. Its entire thickness is about 3 /*. The outer wall of the ductus cochlearis (Fig. 724) consists of the periosteal lining of the bony cochlea, which, however, is thickened and greatly modified to form the ligamentum spirale cochleae. Occupying the whole outer wall, this liga- ment projects inwards inferiorly as a triangular prominence, the crista basilaris, to which the outer edge of the membrana basilaris is attached. In the upper part of the ligamentum spirale the periosteum is of a reddish-yellow colour, and contains, immediately under its epithelial lining, numerous small blood-vessels and capil- lary loops, forming the stria vascularis. The lower limit of this stria is bounded by a prominence, the prominentia spiralis, in which is se
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
