DEVELOPMENT OF THE ORGAN OF HEARING. 



61 



Each cell of the ventral acoustic ganglion (group B) sends 

 efferent processes to the organ of Corti in the cochlea and the 

 acoustic cells of the saccule and posterior semicircular canal and 

 afferent fibres which form the dorsal or lateral root of the 



great sup. pet. 

 chorda tympani 



inf. corp.quadrigem. 

 sup. ped. 

 to sup. oliue 

 — striae acousticae 

 dorsal gang. 



mes. root, 

 acces. gang. 



inf. ped. 

 cerebellum 



gang, of /at. root 



''e. s. canal 

 ^s. s. canal 

 coch. 



Fig. 46. — Showing the Nerve Structures concerned in the Sense of Hearing. 



sac. 



auditory nerve and run to the nerve cells in the opposite side 

 of the medulla oblongata. Some of these fibres form the striae 

 acousticae. 



The third group of cells (C, Fig. 46) forms the vestibular 

 ganglion in the fundus or floor of the internal auditory meatus. 

 Its cells send efferent fibres to the utricle, external and 

 superior semicircular canals, and afferent fibres which form the 

 mesial root of the auditory nerve. This root passes beneath the 

 restiform body (Fig. 46) to terminate in the nerve cells of the 

 acoustic tubercle and trigone in the floor of the 4th ventricle. 

 These nerve cells and fibres are in no sense auditory, but con- 

 cerned with the balancing of the body. 



