516 



PHYSIOLOGY 



lamina to the spiral crest on the outer wall of the cochlea. The length of 

 these fibres increases from O041 mm. at the base of the cochlea to O495 mm. 

 at the helicotrema. 



s.v 



n sp.l 



FIG. 251. Vertical section of the first turn of the human cochlea. (G. RETZIUS.) 

 s.v, scala vestibuli ; s.t, scala tympani ; d.c, canal or duct of the cochlea ; sp.l, spiral 

 lamina ; n, nerve fibres ; Lsp, spiral ligament ; str.v, stria vascularis; s.sp, spiral sulcus ; 

 R, section of Reissner's membrane ; I, limbus laminae spiralis ; m.t, membrana tectoria ; 

 tC, tunnel of Corti ; b.m, basilar membrane ; h.i, h.e, internal and external hair-cells. 



The end-organ of the auditory nerve is represented by the organ of Corti, 

 which rests on the basilar membrane (Fig. 252). It consists of a double 



m.t 



B.M 



FIG. 252. Section through the end-organ of the auditory nerve in the cochlea 



(organ of Corti). 



BM, basilar membrane ; -c, canal of Corti ; no, rods of Corti ; m and OH, inner 

 and outer hair-cells ; sc, sustentacular cells ; An, auditory nerve ; mt, membrana 

 tectoria. 



row of stiff cells, the inner and outer rods of Corti, which run throughout the 

 whole length of the scala media and are surrounded by sense epithelium, the 

 hair-cells. On the inner side of the rods of Corti there iifa single row, on the 

 outer side three rows of hair-cells. Between the hair-cells are the sustenta- 

 cular cells, or cells of Deiters, the peripheral processes from which join 



