THE NERVOUS SYSTEM. 



Organ of Corti (Figs. 394, 395). This consists of (1) the 

 rods of Corti ; (2) a reticular lamina ; (3) outer hair-cells ; (4) 

 inner hair-cells. 



V t' n*' * 





FIG. 394. Organ of Corti : at x the tectorial membrane is raised ; e, outer sus- 

 tentacular cells ; d, outer auditory cells ; /, outer pillar cells : g, tectorial membrane ; 

 h, inner sustentacular cells; i,p, epithelium of the sulcus spiralis internus; k, labium 

 vestibulare ; e, tympanic investing layer ; m, outer auditory cells ; n, n, nerve-fibers 

 which extend through the tunnel of Corti ; o, inner pillar cell; q, nerve-fibers; 6, 6, 

 basilar membrane ; a, epithelium of the sulcus spiralis externus ; r, cells of Hensen ; 

 s, inner auditory cell ; I, ligamentum spirale (after Eetzius). 



Rods of Corti. These are of two kinds, the inner, of which 

 there are 5600, and the outer, 3850 in number. They are both 



FIG. 395. Section of Corti's organ from guinea-pig's cochlea : 8T, scala tympani : 

 TC, tunnel of Corti ; a, bony tissue or spiral lamina ; 6, 6, fibrous tissue covering 

 same continued as substantia propria of basilar membrane ; c, c, protoplasmic envelope 

 of Corti's pillars (e, e) d, endothelial plates ; /, heads of pillars containing oval 

 areas ; g, head plates of pillars ; h, h', inner and outer hair-cells ; m, membrana 

 reticularis ; fc, I, cells of Hensen and Claudius ; n, n, nerve-fibers ; L cells of Deiters 

 (after Piersol). 



stiff, striated cells ; the shape of the inner has been compared to 

 that of the human ulna, with a depression like the sigmoid cavity 

 and processes like the coronoid and olecranon ; the shape of the 



