96 LABORATORY OUTLINE OF NEUROLOGY 



they will be seen to connect with the dentate nucleus. This 

 tract is the chief efferent pathway from the cerebellum. 

 Accompanying the tract for the red nucleus are other descend- 

 ing fibers for the motor centers in the reticular formation 

 (tegmentum) of the midbrain and oblongata (tr. cerebello-teg- 

 mentalis) which cannot easily be separated from those for 

 the red nucleus (Herrick ('18), Fig. 87). 



There is another important component of the brachium 

 conjunctivum, the tractus spino-cerebellaris ventralis of Gow- 

 ers (see Section 96). At the lower end of the oblongata cau- 

 dad of the inferior olive this tract, together with the spinal 

 lemniscus, can be recognized, in the gross preparation, lying 

 immediately ventrally of the tr. spino-cerebellaris dorsalis of 

 Flechsig and dorsally and laterally of the olive. Dissect the 

 mixed bundle out in this position and trace it forward. It can 

 be followed to a level near the pons. Its further course (which 

 cannot easily be dissected) is as follows (see Section 107) : At 

 about the level of the upper border of the pons the fibers of 

 the ventral spinocerebellar tract separate from the lemniscus 

 fibers and turn abruptly dorsal ward, then backward, to 

 enter the brachium conjunctivum. Through the brachium 

 conjunctivum they enter the vermis of the cerebellum medially 

 of the dentate nucleus. 



106. The cochlear nuclei and lateral lemniscus. Deter- 

 mine again the positions of the cochlear and vestibular roots of 

 the VIII nerve. Identify the dorsal and ventral cochlear 

 nuclei. Fibers from the dorsal nucleus (striae medullares 

 acusticse) can be followed across the floor of the fourth ven- 

 tricle. At the midline these fibers decussate and pass ventral- 

 ward to the superior olive of the opposite side. From the 

 ventral cochlear nucleus fibers of the trapezoid body pass 

 ventralward and medialward, at first embedded in the deepest 

 fibers of the pons. They reach the superior olive of the same 

 and the opposite side. They can be dissected, though their 

 separation from the deep fibers of the pons is very difficult. 

 From the superior olive of the opposite side the conduction 

 path which continues both the dorsal and the ventral cochlear 

 pathways (striae medullares and trapezoid bodies respectively) 

 is the lateral lemniscus, whose fibers terminate in the colliculus 



