226 ELEMENTS OF MAMMALIAN ANATOMY. 



of the foot. It supplies the skin along its course and 

 the peronei muscles. The anterior tibial nerve passes 

 down on the cephalic aspect of the tibia beneath the 

 extensor longus digitorum muscle to the tarsal region, 

 where it anastomoses with a branch of the external 

 cutaneous, and supplies the skin, tibialis anticus, and 

 the extensor muscles. 



The lesser sciatic nerve is a branch of the greater 

 sciatic in the buttock region. The pyriformis, obturator, 

 gemelli, quadratus femoris, semitendinosus, and semi- 

 membranosus muscles are innervated by the greater 

 sciatic nerve (Figs. 48 and 102). 



The sacral plexus is an irregular network composed 

 of the ventral branches of the three sacral nerves and 

 two or more small twigs from the seventh lumbar (Fig. 

 102). This plexus is seldom the same in any two cats. 

 From it are given off the internal pudic and glutei nerves. 

 The former supplies the prostate and anal glands, the 

 sphincter muscle, and the penis. The latter supplies 

 the glutei and pyriformis muscle. 



THE SYMPATHETIC NERVOUS SYSTEM. 



The sympathetic nervous system is composed chiefly 

 of a pair of nerve-cords extending from the base of the 

 skull to the root of the tail, a number of ganglia and 

 branches supplying the thoracic and abdominal viscera, 

 and numerous minute fibers supplying the muscular 

 walls of the blood-vessels in all parts of the body. The 

 sympathetic system supplies all non-striped or involun- 

 tary muscles in any part of the body. 



In order to demonstrate this system successfully, one 

 should use a lean injected specimen. After the cat has 

 been securely nailed on its back to the tray, the entire 



