THE NERVOUS SYSTEM OF THE PIG 



723 



The spinal nerves number on each side eight in the cervical region, fourteen 

 (commonly) in the thoracic, seven in the lumbar, and four in the sacral. Some 

 of the special features of the nerves of the limbs are as follows: 



The brachial plexus is derived from the same nerves as in the ox, but the root 

 furnished by the sixth cervical is relatively smaller. The plexus consists of two 

 parts, the upper of which emerges alcove the scalenus, the lower between the two 

 parts of that muscle. The more important differences in the nerves emanating 

 from the plexus from the arrangement in the ox occur in the lower part of the limb. 

 The cutaneous branch of the radial nerve divides at the carpus into branches which 

 concur with the dorsal l)ranch of the ulnar nerve in supplying the dorsal digital 

 nerves, two for each digit. The volar digital nerves, also two for each digit, are 

 formed by the terminal branches of the median nerve and the volar or deep branch 



Deep peroneal 

 nerve 



Superficial 

 peroneal nerve 



Internal 



saphenous 



nerve 



Tibial nerve 



Internal plantar 



nerve 



External 



\ plantar 



nerve 

 . Dorsal 

 branch 



Anasto- 

 motic 

 branch 



Fig. 537. — Nerves op Distal Part of Right Hind 



Limb of Pig, Anterior View (Schematic). 



p. Dorsal proper digital nerves. 



Fig. 538. — Nerves, of Distal Part of Right Hind 



Limb of Pig, Posterior View (Schematic). 



p. Plantar proper digital nerves. 



of the ulnar nerve. The formation and arrangement of the digital nerves are 

 indicated in the annexed schematic figures. 



The lumbo-sacral plexus is derived from the ventral branches of the last three 

 lumbar and first sacral nerves. The distribution of the branches of the plexus 

 differs chiefly in the distal part of the limb. The superficial peroneal nerve is 

 large and terminates by forming the greater part of the dorsal digital nerves. 

 The latter, two for each digit, are also in part formed by the terminal branches of 

 the deep peroneal nerve. 



The tibial nerve divides at the tarsus into internal and external plantar nerves. 

 The latter divide to form the plantar digital nerves, two for each digit. In addi- 

 tion, the external plantar nerve supplies a branch to the dorsal aspect of the outer 

 (fifth) digit. The arrangement of the digital nerves is indicated by the annexed 

 schematic figures. 



