THE MAMMALIAN NERVOUS SYSTEM 75 



medullares acusticse. The fibers of the trapezoid body may 

 not be easily distinguished from the deepest fibers of the pons 

 which lie ventrally of them. The superior olive is a small gray 

 nucleus lying deeper than any of these fibers and laterally of 

 the great medial lemniscus tract (medial fillet). If the lateral 

 lemniscus is not easily identified in this region, locate it in sec- 

 tions at the level of the upper border of the pons and trace it 

 back to the superior olive. In sections through the midbrain 

 the lateral lemniscus can readily be followed to its termina- 

 tions in the medial geniculate body and inferior colliculus, and 

 the fibers from the later to the medial geniculate body in the 

 brachium of the inferior colliculus are also easily identified. 

 Diagrams illustrating the connections of the cochlear nuclei 

 with other centers of the brain are given in many texts. See 

 Bailey ('16), Fig. 338, p. 500; Herrick ('18), Fig. 96; Morris 

 ('14), Fig. 650, p. 824; Rauber-Kopsch ('12), Fig. 258, p. 269; 

 Villiger ('12); Fig. 165, p. 179. 



83. Nervus vestibularis and its nuclei. Locate in your micro- 

 scopic sections and draw the vestibular root of the VIII 

 nerve and its nuclei (see Section 62 (5) and (6)), viz.: 



Nucleus n. vestibuli superior (of Bechterew). 



Nucleus n. vestibuli lateralis (of Deiters or nucleus vestibu- 

 laris magnocellularis) . 



Nucleus n. vestibuli medialis (of Schwalbe, also called nu- 

 cleus dorsalis, principal nucleus, and nucleus vestibularis 

 triangularis) . 



Nucleus n. vestibuli spinalis. 



The fibers of the vestibular root pass inward beneath the 

 inferior cerebellar peduncle (restif orme body) and at right 

 angles to its fibers. The vestibular nuclei lie in the floor of the 

 fourth ventricle medially of the restif orm body (Herrick ('18), 

 Figs. 86 and 96). All of these nuclei (especially the nucleus 

 medialis) send fibers into the reticular formation of the same 

 and the opposite side for motor reflexes of the oblongata. Find 

 in these sections, if possible, the fibers which pass from the ves- 

 tibular root and nucleus to the restiforme body and thence into 

 the cerebellum the cerebellar root of the VIII nerve and the 

 vestibulo-cerebellar tract. These fibers pass directly dorsal- 

 ward from the upper end of the vestibular nuclei (see Herrick 



