756 



PHYSIOLOGY. 



the lamina spiralis. The vestibular portion consists of an expanded 

 body, the utricle, and a smaller body, the saccule. Within these com- 

 partments are two calcareous bodies: the otolitlis. The vestibular 

 filaments of the cochlear nerve are distributed to the ampullas, 

 utricle, and saccule. In the first the fibers terminate in elevations 

 called cristce acusticce; in the last two they end as oval plates, 

 maculcB, colored by yellow pigment. 



Organ of Corti. The organ of Corti contains the following 

 elements : 



St 



Fig. 312. Section through the Uncoiled Cochlea (I) and through 

 the Terminal Nerve Apparatus of the Cochlea (II). (MUNK, after 

 HEN SEN.) 



I. Fr., Round window. H, Helicotrema. St., Stapes. 



II. ss, Huschke's process. &', Basilar membrane, e, Corti's arch, g, Sup- 

 porting cells, h, Cylindrical cells, i, Deiters's hair-cells, c, Membrana tec- 

 toria. n, Nerve-fibers, ri, Nonmedullated nerve-fibers. 



1. Arches of Corti. They are formed of an internal and external 

 pillar whose pedestals rest upon the basilar membrane. The arches 

 intercept the canal of Corti. 



2. Internal Auditory Cells. Inward from the internal pillar of 

 Corti is found a layer of auditory cells. These cells contain nuclei, 

 while their superior extremities terminate in a plateau having long 

 ciliated prolongations; their inferior extremities are in relation with 



