654 



THE EAR. 



the osseous lamina, into the basilar membrane. Near its termination, 

 close to the junction with the basilar membrane, it is perforated 

 with a number of regularly-arranged, elongated apertures (fig. 470, ;;), 

 wliich serve for the transmission upwards of the nerve-fibres. Tlie 

 latter, in their course from the spiral ganglion to the auditory 

 epithelium, are lodged, as far as this, in canals in the lower osseous 

 part of the spiral lamina. Their arrangement here will be afterwards 

 more fully described. 



Fig. 4G9. 





L. S}-). 



Fig. 469. — Vertical Section op the first turn op the Cochlea of a Child a 

 Year and a Half old. 100 Diameters (Waldeyer). 



SV, scala vestibuli ; «ST, scala tympani ; DC, duct or canal of the cochlea ; L.sp.o^, 

 L.sp.o"-, vestibular and tympanal layer of the osseous spiral lamina with the stratum of 

 nerve-fibres, N, between ; a, a, outer bony wall of cochlea ; i, b, and d, periosteum^ ; 

 e, e, connective tissue thickening forming at L.Sp. the spiral ligament ; St.v., stria 

 va^scularis ; L.Sp.a, prominence known as the accessory spiral ligament, containing a 

 spirally running blood-vessel, ihQ vas promincns ; S.sp.i., spiral groove (inner) ; S.sp,e., 

 so-called external spiral r/roove ; R, E^, section of Reissner's membrane, the middle part 

 indicated only by a dotted line ; from R to Cr., limbus laminte spiralis ; M.L, membrana 

 tectoria, somewhat raised up from its natural position ; / — p, organ of Corti ; /, nerves 

 turning up to enter epithelium ; ff, inner hair-cell region ; h, region of the outer hair- 

 cells ; I, basilar membrane underneath rods of Corti, 



