432 



PRACTICAL ANATOMY. 



two lips : an upper, the labium vestibulare, and a lower, 

 the labium tympanicum ; the groove between them is 

 designated the sulcus spiralis. Attached between the 

 labium vestibulare and the modiolus is the membrane of 

 Reissner, which is attached to the inner wall of the 

 cochlea, and subdivides the scala vestibuli into a lower, 

 smaller canal, the scala media, and the larger, upper canal, 



st 



FIG. 190. I. SECTION THROUGH THE UNCOILED COCHLEA. II. SECTION THROUGH 

 THE TERMINAL NERVE-APPARATUS OF THE COCHLEA. 



I. F.r., Fenestra rotunda: II. the helicotrema; St., the stapes. II. z. Huschke's proc- 

 ess ; b', basilar membrane: e. Corti's arch: g. supporting cells; h, cylindrical cells; i, 

 Deiter's hair-cells ; c, membrana tectoria ; n, nerve-fibres ; n', non-medullated nerve-fibre*. 



the scala vestibuli proper. Between the membrane of 

 Reissner and the labium vestibulare arises the membrane 

 of Corti, which passes outward parallel with the mem- 

 brana basilaris, and is inserted on the inner wall of the 

 cochlea, forming a canal called the ductus auditorium; it 

 contains the organ of Corti. The organ of Corti consists 

 of upward of three thousand arches, which spring from 

 the labium tympanicum by the rods of Corti, and conjoin 



