Human anatomy, including structure and development and practical considerations . n (inner) and a lateral ((niter) part. The former,known as the zona arcuata, is thin and supports the modified neuroeiMthelium constituting; theorigan of Corti; the outer part, named the zona pectinata, is the thicker division and lies externalto the foot-plates of the outer rods of Corti. Tiie l)asiiar membrane is made up of three distinctlavers, the epithelium, the siibstautia propria and the tympanic latnella. The substantia propriais formed of an almost homoi^eneous connective tissue with a few nuclei and fin
Human anatomy, including structure and development and practical considerations . n (inner) and a lateral ((niter) part. The former,known as the zona arcuata, is thin and supports the modified neuroeiMthelium constituting; theorigan of Corti; the outer part, named the zona pectinata, is the thicker division and lies externalto the foot-plates of the outer rods of Corti. Tiie l)asiiar membrane is made up of three distinctlavers, the epithelium, the siibstautia propria and the tympanic latnella. The substantia propriais formed of an almost homoi^eneous connective tissue with a few nuclei and fine fibres, whichradiate toward the outer edge of the spiral lamina. The fibres of the zona arcuata are very fineand interwoven, appearing to be an extension of those of the lower lij) of the limbus, whilststraight and more (listinct fibres stretch from the outer rods of Corti to the spiral ligament andconstitute the so-called auditory strings. According to the estimate of Retzius, there are 24,000 Fig. 1272. Bony capsiiof cochlea Spiral ligament Crista basilaris Basilarmembrane. Nerve-fibres Uone Vas spiralisCross-section of ductus coclileai is from human cochlea. < 90. Drawn from preparation made t)y Dr. Ralph Butler. of these special fibres. Their length increases from the base toward the apex of the cochlea, inagreement with the corresponding increase in breadth of the basilar membrane. The tympaniclamella contains numbers of fusiform cells of immature character interspersed with fibres. Inthis location the differentiation of the mesoblastic cells lining the tympanic canal has neveradvanced to the production of typical endothelial plates, the free surface of the lamella beinginvested by the short fusiform cells alone. The inner zone of this layer contains capillarieswhich empty into one, or sometimes two, veins, frequently seen under the tunnel of Corti andknown as the vas spirale. The epithelium covering the inner zone of the basilar membraneforms the organ of Corti, the
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Keywords: ., bookauthormc, bookcentury1900, bookdecade1910, booksubjectanatomy
