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TEXT-BOOK OF PHYSIOLOGY. 



carbonate held together by a gelatinous material. The crystals are 

 known as otoliths. 



The fibers of the vestibular nerve, arising from the cells of the 



ganglion of Scarpa in the internal 

 auditory meatus, send their peri- 

 pherally directed branches through the 

 foramina in the inner wall of the vesti- 

 bule, through the walls of the utricle 

 and semicircular canals near the am- 

 pulla. As the fibers approach the 

 maculae acusticae they subdivide into 

 delicate fibrillae, which ultimately 

 become histologically and physiologi- 

 cally related to the neuro-epithelium. 

 From the relation of the nerve-fibers 

 to the epithelium, the latter must be 

 regarded as the highly specialized 

 terminal organ of the vestibular portion 

 of the auditory nerve. 



The cochlea is a closed mem- 

 branous tube situated between the 

 osseous lamina spiralis and the outer 

 bony wall. A transection of the entire 

 cochlea shows the relation of the os- 

 seous and membranous portions (Fig. 



316). The cochlear tube is triangular in shape. The base is attached 

 to the bony wall, the apex to the edge of osseous lamina spiralis. 

 One side of the tube forms 

 in part the membrane of 

 Reissner, the other side forms 

 in part the basilar membrane. 

 The sides of the cochlea to- 

 ward the scala vestibuli and 

 scala tympani are covered 

 with epithelium. The tri- 

 angular cavity of the cochlear 

 tube is known as the scala 

 media. The inner surface 

 of the cochlear tube is lined 

 by epithelium, which be- 

 comes extraordinarily modi- 

 fied and specialized along the 

 surface of the basilar membrane, to constitute what is known as 

 The Organ of Corti. In Fig. 316 this organ is represented as 

 it appears on cross-section of the cochlea. It consists primarily of 



FIG. 315. SECTION OF WALL OF 

 UTRICLE OF THE INTERNAL 

 EAR, through macular region, 

 from rabbit, showing otoliths 

 (o), embedded within granu- 

 lar substance (g). h. Cili- 

 ated cells with processes (p), 

 extending between sustentacu- 

 lar elements (s). m. Base- 

 ment membrane, n. Nerve- 

 fibers within fibrous tissue (/) 

 passing toward hair-cells and 

 becoming non-medullated at 

 basement-membrane. (After 

 Piersol.} 



FIG. 316. A TRANSVERSE SECTION OF A 

 TURN OF THE COCHLEA. 



