562 



THE HUMAN BODY. 



former communicates below with the perilymph cavity of the 

 vestibule, while the scala tympani abuts below on the round 

 foramen, which, as has already been pointed out, is closed by 

 a membrane. The membranous cochlea contains certain 



FIG. 166. Section of one coil of the cochlea, magnified, SV, scala vestibnli ; 

 R, membrane of Reissuer; CC, membranous cochlea (scala media); Us, limbus 

 lamince spiralis; t, rectorial membrane; ST,- scala tympani; also, spiral lamina; 

 Co, rods of Corti ; 6, basilar membrane. 



solid structures seated on the basilar membrane and forming 

 the organ of Cor^i the rest of its cavity is filled with endo- 

 lymph, which has free passage to that in the sacculus. ^ 



The Organ of Corti. This contains the end organs of 

 the cochlear nerves. Lining the sulcus spiralis are cuboidal 

 cells; on the inner margin of the basilar membrane the cells 

 become columnar, and then are succeeded by a row which bear 

 on their upper ends a set of short stiff hairs, and constitute 



A B 



4' ** 



1 



\ -f F i G 'i! 67 V~ Tile rods of Co' 1 * 1 '- ^4i a pair of rods separated from the rest ; B, a 

 m ot tne basnar membrane with several rods on it, showing how they cover in 

 tne tunnel of Corti ; i, inner, arid e, outer rods ; 6, basilar membrane : r, reticular 

 membrane. 



the inner hair-cells, which are fixed below by a narrow apex 

 to the basilar membrane ; nerve-fibres enter them. To the 

 inner hair-cells succeed the rods of Corti (Co, Fig. 166), 

 which are represented much magnified in Fig. 167. These 

 rods are stiff and arranged side by side in two rows, leaned 



