716 



THE NERVOUS SYSTEM OF THE OX 



The pons is smaller, both transversely and longitiKlinally, than that of the 

 horse. It is strongly convex and has a distinct central doi^ression. 



The cerebellum is smaller and more angular in form than in the horse. The 

 vermis is large and has a distinct depression on its anterior face for the posterior 

 corpora qiiadrigemina. The hemispheres are relatively small and are not clearl}^ 

 divided into tal)ulations. The anterior peduncles are very short. 



The cerebral peduncles are short. A small eminence in the locus perforatus 

 posticus is caused by the presence of the interpeduncular ganglion. The internal 

 geniculate body is prominent. The pineal body is long and fusiform, and is often 

 pigment etl in spots. The third ventricle forms two considerable recesses in relation 

 to the pineal body: one (R. pinealis) extends up into the body; the other (R. 



suprapinealis) is a long tubular prolongation 

 in front of it. 



The optic tracts cross the cerebral pedun- 

 cles almost at a right angle. 



The pituitary body is situated in a 

 deep fossa and is surrounded by a plexus 

 of vessels. 



The cerebral hemispheres are shorter, 



higher, and relatively wider than in the 



horse. The frontal poles are small, the 



occipital large. Viewed from the side, the 



dorsal surface is strongly convex. The 



highest point of the dorso-medial border 



is a little in front of its middle and 



marked prominence termed the 



(Polus sagittalis 



dorsalis) . An- 



drops abruptly, 



deep transverse 



the basal and 



Fit 



529. 



Jerebral Hemispheres of Ox, 

 Dorsal View. 

 a, Transverse fissure; b, lateral fissure (of 

 Sylvius); c, coronal fissure; d, diagonal fissure; 

 e, entomarginal fissure; /, marginal fissure; g, 

 ectoniarginal fissure; h, suprasylvian fissure. 

 (After EUenberger, in Leisering's Atlas.) 



lorms a 



sagittal or marginal pole 



s. prominentia marginalis 

 terior to this the l:)order 

 being cut into by the 

 fissure. The arachnoid on 



anterior parts of the hemispheres is usually 

 pigmented. The corpus callosum extends 

 through a little more than a third of the length of the hemisphere. The pattern 

 of the fissures and gyri of the pallium is somewhat simpler than in the horse. 



1. The lateral fissure (of Sylvius) is very deep. Its middle branch extends almost ver- 

 tically upward on the middle of the lateral surface of the hemisphere, and is separated by a 

 gyrus of variable width from the suprasylvian fissure. The anterior branch runs forward about 

 parallel with the sulcus rhinalis anterior, from which it is separated by the short gyri of the insula. 

 The latter are covered to a small extent only by the overhanging gyri (operculum). The posterior 

 branch may run liack a distance of oidy about 1.5 cm. and encl in T-shaped manner, or it may 

 join the sulcus rhinalis posterior. 



2. The suprasylvian fissure is deep and very distinct. It extends in an undulating manner 

 from the lateral surface of the occipital pole to the outer side of the sagittal pole. Here it may 

 be interrupted or may be continued by the coronal fissure, whicli descends to the frontal pole 

 and divides into two sliort branches. 



3. The diagonal fissure (S. diagonalis) begins in front of the stem of the lateral fissure and 

 runs upwtird and forward. Its form is very variable. 



4. The transverse fissure cuts obliquely into the dorsal border in front of the sagittal 

 pole. It is short ami deep and commonly communicates with the suprasyhian and coronal 

 fissures. 



5. The marginal fissure is distinct. It extends from the sagittal pole to the occipital 

 pole. It is flexuous and deviates outward somewhat in its posterior two-thirds. 



6. The entomarginal fissure lies medial and parallel to the posterior part of the 

 preceding. 



7. The ectomarginal fissure is lateral and parallel to the marginal fissure. It does not ex- 

 tend so far in either direction as th(> latter and is often more or less broken up by annectent gyri. 



8. The sulcus rhinalis is more open than in the horse, since it is not overlapped by the 

 gyri above it. 



9. The calloso-marginal fissure is flexuous and not so regular as in the horse. It is often 



