THE NERVOUS SYSTEM OF THE PIG 



843 



related to the anterior mesenteric artery. The two are connected by ganghated 

 cords, and are similarly connected with the ganglia of the opposite side, so that the 

 arrangement is plexiform. The coeliac plexus is more complex than that of the 

 horse m correlation with the compound character of the stomach. The posterior 

 mesenteric gangUon is small and is situated behind the artery of like name It 

 receives fibers from the last three or four lumbar ganglia and two fasciculi from the 

 anterior mesenteric ganglia. The pelvic viscera receive branches from the posterior 

 mesenteric ganglion and from the 



sacral ganglia; the latter number 

 five pairs, and the right and left 

 trunJjs are connected here by trans- 

 verse anastomoses. The coccygeal 

 trunks unite at a single fourth coc- 

 cygeal ganglion, then separate, and 

 reunite at the sixth coccygeal gan- 

 glion. 



Longitudinal fissure Frontal pole 



THE 



NERVOUS SYSTEM 

 THE PIG 



OF 



The spinal cord weighs about 

 one and a half ounces _(ca. 42 gm.). 

 It is almost circular in cross-section, 

 except at the enlargements, where 

 it is somewhat flattened dorso-ven- 

 trally. The conus medullaris ex- 

 tends to the anterior part of the 

 third sacral segment. The epidural 

 space is occupied by a large quan- 

 tity of fat. 



The brain in adults of medium 

 size weighs about four to four and 

 a half ounces (ca. 125 gm.). When 

 viewed from above, the cerebrum 

 has an elongated oval form. The 

 hemispheres are widest at the pos- 

 terior third. The occipital pole is 

 larger than the frontal pole. The 

 medulla oblongata is relatively 

 broad. The cuneate tubercle is very 

 large and is limited laterally by a 



groove. The corpus trapezoideum is very wide laterally. The pons is less promi- 

 nent than in the ox. The cerebellum is very wide and short. Its anterior face is 

 flattened and presents a depression for the corpora quadrigemina. The vermis is 

 large. The hemispheres consist of a large medial part and a small lateral part. 

 The cerebral peduncles are very short. The posterior corpora quadrigemina are 

 wide apart, rounded, and relatively large. The medial geniculate body is promi- 

 nent. The cerebral hemispheres are somewhat bean-shaped in lateral profile, the 

 convex border being dorsal. The arrangement of the gyri and sulci is simpler than 

 in the horse or ox. 



The principal fissures are as follows : 



1. The lateral fissure (of Sylvius) begins at the sulcus rhinalis and runs upward and 

 somewhat backward on the depressed part of the lateral surface of the hemisphere; it appears 



Cerebellum 



Medulla oblongata 



Fig. 671. — Brain or Pig; Dohsal View. 

 Fissures: 1, Lateral, 2, suprasylvian, with anterior {2') 

 and dorsal (S") branches; 3, diagonal; 4, coronal; 6, presyl- 

 vian; 6, marginal; 7, ectomarginal ; 5, entomarginal; 9, cruciate. 

 Two different arrangements of the coronal and cruciate fissures 

 are seen on the two sides. 



