92 LABORATORY OUTLINE OF NEUROLOGY 



They will be found to form three chief systems. The most 

 medial and the most lateral bundles of the fiber complex which 

 forms the ventral part of the cerebral peduncle in front of the 

 pons, are cortico-pontile tracts from the cerebral cortex to the 

 pontile nuclei (cf. Herrick ('15), Figs. 75, 87), where, after a 

 synapse, their nervous impulses are taken up by the neurones 

 of the pontile nuclei and carried through the brachium pontis 

 to the cortex of the opposite cerebellar hemisphere. The middle 

 bundles of the cerebral peduncle contain the pyramidal tract 

 (tr. cortico-spinalis) which can be dissected through the pons to 

 reappear below on the ventral surface of the oblongata as the 

 pyramid (pyramis). Its further course will be dissected later. 

 The chief constituent of the brachium pontis is thus seen to be a 

 system of fibers arising in the pontile nuclei for carrying ner- 

 vous impulses from the cerebral cortex (by the cortico-pontile 

 tracts) to the cerebellar hemispheres of the opposite side. 



105. Brachium conjunctivum. — First examine the anterior 

 medullary velum (velum medullar e anterius), within which near 

 the median plane careful teasing will reveal a thin sheet of 

 fibers running longitudinally between the roof of the colliculus 

 inferior and the vermis cerebelli. This tractus tecto-cerebellaris 

 (Herrick ('15), Fig. 87) is not commonly included in the brach- 

 ium conjunctivum, but it can best be seen at this time. 



The true brachium conjunctivum (superior peduncle) forms 

 the medial part of the cerebellar peduncle complex at the point 

 where it joins the cerebellum (Fig. 11). Its fibers are directed 

 from the cerebellum forward and downward. Their further 

 dissection in the midbrain (decussation and connection with 

 the red nucleus) will not be taken up at this time. They should, 

 however, be dissected up into the cerebellum, where 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 descending fibers for the 

 motor centers in the reticular formation (tegmentum) of the 

 midbrain and oblongata (tr. cerebello-tegmentalis) which cannot 

 easily be separated from those for the red nucleus (Herrick 

 ('15), Fig. 87). 



There is another important component of the brachium 

 conjunctivum, the tractus spino-cerebellaris ventralis of Gowers 



