654 



NERVOUS SYSTEM OF THE HORSE 



accessory nerves are connected by a linear series of roots with the lateral aspect of 

 the ventral surface of the medulla. The spinal part of the accessory nerve comes 

 forward along the edge of the medulla to join its medullary root. 



The twelfth or hypoglossal nerve arises from the posterior part of the medulla 

 along the lateral edge of the pyramid. 



The parts that are visible when the brain is viewed from above are the cerebral 

 hemispheres, the cerebellum, and part of the medulla oblongata. The cerebral 



I 



Longitudinal 



fissure Olfactory bulb 



ll 



Transverse fissure 



Frontal pole of hemisphere 



Cerebrum 



Occipital pole of 

 hemisphere 



Cerebellum 



Medulla oblongata 



Fig. 498. — Brain op Horse, Dorp.\l View, .\bout f N.\tural Size. 

 1, Entomarginal fi.ssure; 2, marginal fissure; S, ectomarginal fissure; 4. suprasylvian fissure. 





hemispheres form an ovoid mass, and are separated from each other by the median 

 longitudinal fissure, in which the falx cerebri is situated. Their surfaces are marked 

 by thick folds, the gyri cerebri, separated by sulci. The upturned ends of the 

 olfactory bulbs are seen in front of the frontal poles of the hemispheres. The 

 occipital poles of the hemispheres overlie the anterior part of the cerebellum, from 

 which they are separated i)y the transverse fissure and the tentorium cerebelli 

 contained in it. The cerebellum is a much smaller rounded mass which conceals 

 the greater part of the medulla oblongata. Its surface is divided into a middle 



