THE CEREBELLUM. 243 



either directly or by means of basket cells or other cells with 

 short neurites as indicated in the accompanying schemes (Fig. 



123). 



Recent experimental work on the cerebellum of the rabbit has 

 led Van Gehuchten to the conclusion that the in-coming fibers 

 enter the cerebellum in the corpus restiforme and brachium 

 pontis, while the out-going fibers go by way of the brachium' 

 conjunctivum. 



The fibers which enter the cerebellar cortex may be grouped 

 under the following categories: 



a. Primary somatic sensory fibers from the roots of the spinal, 

 vestibular and trigeminal nerves. 



b. Secondary somatic sensory fibers. These arise from the 

 cells of the nuclei of the dorsal funiculi and from the superior and 

 lateral nuclei of the vestibular nerve. The fibers from the nuclei 

 of the funiculi run in part in the corpus restiforme of the same 

 side, in part as external arcuate fibers in the corpus restiforme 

 of the opposite side. 



c. Fibers from the gray matter of the cord of the same and 

 opposite side which run up in the fasciculus spino-cerebellaris 

 ventralis (tract of Gowers) and enter the cerebellum in part by 

 way of the brachium conjunctivum and in part by the corpus 

 restiforme, to end in the superior vermis and hemispheres. 



d. Tractus olivo-cerebellaris, from the lower olive to the cere- 

 bellar cortex. 



e. Fibers from the nuclei of the pons. Some of these constitute 

 with Purkinje cell neurites a two-linked commissure between the 

 two hemispheres of the cerebellum. Others forward impulses 

 which are brought to the pons from the cerebral hemispheres 

 by way of the pyramids. 



f. Fibers from the nucleus ruber to the cerebellum by way of 

 the brachium conjunctivum (Edinger's tractus tegmento-cerebel- 

 laris). Recent researches render the existence of such fibers very 

 doubtful. 



g. Fibers from the nucleus of the lateral lemniscus and the 

 posterior colliculus of the corpora quadrigemina. These are 

 secondary nuclei of the auditory paths. 



