722 



THE NERVOUS SYSTEM OF THE PIG 



The cranial nerves ])r(>sent the following special features: 



The third, fourth, sixth, and tlu^ ophthahnic and maxillary divisions of the 

 fifth nerve, emerge together as in the ox. 



The lacrimal nerve resembles that of the horse, the frontal that of the ox. 

 The naso-ciliary nerve is relatively large and sends numerous filaments to the ocular 

 muscles. The maxillary nerve has a very short course in the pterygo-palatine 

 fossa. The infraorbital nerve is large in correlation with the development of the 

 snout which receives numerous branches. The mandibular nerve emerges through 

 the foramen lacerum anterius. The superficial temporal nerve is small; according 

 to Moussu it furnishes the excito-secretory fibers to the upper part of the parotid 

 gland, while those going to the lower part are derived from the mylo-hyoid nerve. 



The inferior buccal nerve j^asses downward and forward under cover of the 



Ultt'ir nerve 

 (dorsal brunch) ~' 



Anastomotic 

 branch 



Radial 



nerve 



(cutaneous 



l.niiicli) 



Ulnar nerve 

 Dorsal branch 



'Deep branch 



Fig. .5.35. — Nkrves of Dist.\i, P.\kt ok Rkjiit Fore 



LiMH OF Pi<i, Anterior V^iew (SciiEM.vno). 



c, Dor.tal common digital nerves; p, dorsal proper 



digital nerves. 



Fni. 536. — Nerves of Distal P.\rt of Right Fore 



Limb of Pig, Posterior View (Schematic). 



p, Volar proper digital nerves. 



parotid gland and accompanies the parotid duct, with which it turns around the 

 lower border of the jaw in front of the masseter. 



The vagus bears a jugular gangUon and a ganghon nodosum ; the latter occurs 

 at the point of origin of the superior laryngeal nerve, and may be as large as a small 

 pea. Proximal to this the vagus is easily dividcnl into two strands, one of which is 

 the accessory component. The a\so])hageal trunks form a posterior oesophageal 

 ]:»Iexus, as in man, from which two nerves issue. The inferior nerve is small and 

 ramifies on the parietal surface of the stomach. The superior trunk is much larger; 

 it gives branches to the stomach, crosses the lesser curvature of that organ, and 

 joins the solar pl(>xus. 



The hypoglossal nerve may present a small dorsal root, on which there is a 

 minute hypoglossal ganglion (of Froriep). 



