i88 



THE NERVOUS SYSTEM 



dial geniculate body is a way-station on the auditory path to the cerebral cor- 

 tex, the inferior colliculus serves as a center for reflexes in response to sound. 

 The Vestibular Nuclei. The fibers of the vestibular nerve take origin from 

 the bipolar cells of the vestibular ganglion located in the internal auditory meatus 

 (Fig. 135). The cochlear and vestibular divisions of the acoustic nerve sepa- 

 rate at the ventral border of the restiform body. Here the vestibular nerve 



Fig. 135. The vestibular ganglion and the termination of the peripheral branches of its bi- 

 polar cells in a macula acustica: A, Hair cells and B, sustentacular cells of the macula; D, terminal 

 arborization of the peripheral branches of the bipolar cells of the vestibular ganglion (G) about the 

 hair cells of the macula; F, facial nerve; R, central branches of the bipolar cells directed toward the 

 medulla oblongata T. Mouse. Golgi method. (Cajal.) 



penetrates into the brain, passing between the restiform body and the spinal 

 tract of the trigeminal nerve toward the area acustica of the rhomboid fossa. 

 Under cover of the area acustica the fibers divide into short ascending and 

 longer descending branches (Figs. 134, 136). There may be enumerated five 

 cellular masses within which these fibers terminate, namely: (1) the principal 

 or medial nucleus, (2) the descending or spinal nucleus, (3) the superior nucleus 



