80 LABORATORY OUTLINE OF NEUROLOGY 



ficially just dorsally of the inferior olive. In transverse 

 sections of the isthmus region immediately below the decussa- 

 tion of the IV nerves these fibers can be recognized for a short 

 distance on the extreme dorso-lateral surface external to those 

 of the brachium conjunctivum and dorsally of those of the 

 lateral lemniscus. At this point they are turning dorsalward 

 from the brain stem to curve backward into the substance of 

 the cerebellum. 



The superior cerebellar peduncle (brachium conjunctivum) can 

 be easily followed -in the sections from the cerebellum forward 

 and downward into the midbrain to its decussation under the 

 aqueduct of Sylvius and its termination in the red nucleus 

 (nucleus ruber) of the opposite side (see Morris ('14), Fig. 638, 

 p. 811). 



The brachium pontis is also easily identified in the sections. 



All of the cerebellar tracts mentioned in this section should 

 be entered in your drawings of the cross-sections, using reference 

 books to complete the incomplete demonstrations of their 

 courses which have been possible in your microscopic sections, 

 (c) Summary of the cerebellar peduncles. — (See Herrick 

 ('15), Fig. 87.) 



The inferior peduncle (corpus restiforme) is composed chiefly 

 of ascending fibers from the great proprioceptive sensory cen- 

 ters of the spinal cord (dorsal spino-cerebellar tract of Flechsig), 

 from the inferior olive (olivo-cerebellar tract), and from the 

 vestibular root and nucleus of the VIII nerve (vestibulo- 

 cerebellar tract) . 



The middle cerebellar peduncle (brachium pontis) is a system 

 of fibers running from the nuclei of the pons to the opposite 

 cerebellar hemisphere. The nuclei of the pons receive impor- 

 tant descending tracts from the cerebral cortex (cortico-pontile 

 tracts) . The fibers of the brachium pontis arise from the nuclei 

 of the pons, thus transmitting nervous impulses derived from 

 the cerebral cortex to the cortex of the opposite cerebellar 

 hemispheres. 



The superior peduncle (brachium conjunctivum) is the chief 

 efferent pathway from the cerebellum. These fibers arise 

 chiefly from the dentate nucleus (Section 98), enter the mid- 

 brain, and cross to the opposite side under the aqueduct of 



