94 LABORATORY OUTLINE OF NEUROLOGY 



restiforme, but do not remove the VIII root and nucleus. 

 Locate the vestibular (ventral) root of the VIII nerve. Its 

 fibers pass under the corpus restiforme to enter the vestibular 

 nucleus in the floor of the fourth ventricle medially of the cor- 

 pus restiforme. Vestibular VIII root fibers pass from the 

 vestibular root into the corpus restiforme and also other fibers 

 of the second order from the vestibular nucleus to its medial 

 border; but their dissection should not be attempted at this 

 time. Trace the restiform body backward and note that 

 it receives external arcuate fibers from the somatic sensory 

 region of the opposite side. At the level of the inferior olive 

 the restiform body receives on its ventral side a large tract from 

 the olive, but this cannot be dissected at this time without 

 destroying the intervening structures ventrally of the restiform 

 body. At the level of the olive the restiform body turns 

 slightly ventralward, crossing superficially the anterior end of 

 the tuber culum cinereum (tubercle of Rolando or spinal V 

 tract), and then passes backward ventrally of the most super- 

 ficial fibers of the tuberculum cinereum. Dissect out this part 

 of the restiform body and follow it backward into the spinal 

 cord, where it will be seen to form the dorsal spino-cerebellar 

 tract of Flechsig (Section 96). Summarizing the corpus resti- 

 forme, this inferior peduncle of the cerebellum is composed 

 chiefly of ascending fibers from the great proprioceptive sen- 

 sory centers of the spinal cord, the inferior olive, and the 

 vestibular root and nucleus of the VIII nerve. 



104. Brachium pontis. At the base of the cerebellum locate 

 the fibers of the brachium pontis, which form the most lateral 

 fibers of the cerebellar peduncles. Beginning at the most 

 ventral part of the pons, gradually tease off the pons fibers, 

 stripping them upward a few at a time into the cortex of the 

 cerebellar hemisphere, and note the way in which those from 

 the anterior (rostral) border of the pons pass obliquely back- 

 ward ventrally of those from the posterior (caudal) border. 

 Trace these two layers out separately and determine their 

 distribution in the cerebellar hemisphere. In the dissection of 

 the pons be careful to preserve the fibers of the V nerve. The 

 brachium pontis fibers as a whole form two thick layers, the 

 fibrae superficiales and the fibrse profundae, separated by the 



