THE CEREBELLUM 



205 



hemispheres, the brachium pontis is the largest of the three peduncles (Fig. 

 89). But this is not true in most mammals, where, as in the sheep, the cere- 

 bellum receives the majority of its afferent fibers from the spinal cord and medulla 

 oblongata by way of the relatively large restiform bodies (Fig. 91). 



The restiform body ascends along the lateral border of the fourth ventricle; 

 and at a point just rostral to the lateral recess it makes a sharp turn dorsally 

 to enter the cerebellum between the other two peduncles (Figs. 87, 88). It 

 consists of ascending fibers from the spinal cord and medulla oblongata and prob- 

 ably also of descending fibers from the cerebellum to the reticular formation 

 of the medulla (fastigiobulbar tract, p. 211). Among the ascending fibers are 

 those of the following bundles: (1) dorsal spinocerebellar tract, which arises 



/ Tectocerebellar tract 



Cerebellum- 

 Restiform body - 

 Dorsal spinocerebellar tract * N 

 Ventral spinocerebellar tract x^ 



f / 



' .; Corpora quadrigemina 



/ ''! 



Brachiumconjunctivum 



-Pons 

 Fig. 149. Diagram of the spinocerebellar and tectocerebellar tracts. 



from the cells of the nucleus dorsalis of the same side of the spinal cord and 

 ends in the cortex of the vermis; (2) the olivocerebellar tract, which consists of 

 fibers from the opposite inferior olivary nucleus and to a less extent from that 

 of the same side and which ends in the cortex of the vermis and of the hemi- 

 sphere and in the central nuclei; (3) the dorsal external arcuate fibers, from the 

 nuclei of the posterior funiculi of the same side; (4) ventral external arcuate 

 fibers from the arcuate and lateral reticular nuclei (Fig. 104). 



The so-called medial part of the restiform body consists of bundles of fibers 

 belonging to the tractus nucleocerebellaris, which course along the medial side of 

 that peduncle as it turns dorsally into the cerebellum (Fig. 110). These come 

 from the sensory nuclei of the cranial nerves. Most of them arise from the 

 superior and lateral vestibular nuclei or represent the ascending branches of the 



