VETERINARY PHYSIOLOGY 



form in the cord the crossed and direct pyramidal tracts, 

 pass down in the middle part of the crusta (fig. 90, P.) of the 

 crura cerebri, and, after coursing between the superficial and 

 deep transverse fibres of the pons (tig. 87, P.\ come to lie in 

 the ventral pyramids of the medulla (fig. 84, P.). At the 

 lower end of the medulla most of these fibres cross (p. 174) 

 to the lateral column of the cord ; some, however, run down 

 the direct and crossed pyramidal tracts of the same side. 



2. The fibres of the descending ventro-lateral tract, coming 

 originally from the deep nuclei of the cerebellum, take origin, 



V7/7 Acf N 







FIG. 85. Cross Section of Medulla through the Olive. The central canal lias 

 opened out to form the floor of the fourth ventricle, 4th V., the lateral 

 columns are passing out to form the inferior peduncles of the cerebellum : 

 F., fillet; 0., inferior olivary nucleus; P., anterior pyramids; Rest., 

 fibres of restiform body ; V., ascending root of fifth nerve ; VIII. 

 Acc.N., accessory nucleus of the eighth nerve. (After BRUCE.) 



in part at least, in a mass of nerve cells (Deiters' nucleus), which 

 lies in the dorsal and lateral part of the pons Varolii (fig. 87, 

 Deit.). 



C. Commissural Fibres. 



1. The basis bundles of the cord form in the medulla a strong 

 band of fibres connecting the grey matter at different levels, 

 the dorsal longitudinal fasciculus. 



2. A set of fibres run from each olivary body across the 

 middle line to the dentate nucleus of the cerebellum of the 

 opposite side. 



