214 ANIMAL PHYSIOLOGY. 



157. The Sympa- 

 thetic System. This 

 is the portion of the 

 nervous system by which 

 the viscera are princi- 

 pally supplied. The 

 primary part consists of 

 two chains of ganglia, 

 one on each side, in 

 front of the vertebral 

 column, called the pre- 

 vertebral chains, or the 

 great sympathetic. 



In the dorsal, lumbar, 

 and sacral regions, these 

 chains present a ganglion 

 for almost every spinal 

 nerve, and each spinal 

 nerve has a twig of 

 communication with its 

 corresponding ganglion. 

 Inf eriorly the two chains 

 meet together in a gan- 

 glion impar in front of 

 the coccyx. In the neck 



Fig. 108. SYMPATHETIC 

 SYSTEM OF NERVES, a, 

 Superior cervical gan- 

 glion, from which the 

 sympathetic chain is con- 

 tinued regularly down- 

 wards as far as the coc- 

 cyx, where it communi- 

 cates with its fellow. It 

 is likewise continued ir- 

 regularly in the cranium. 

 At b, the chains of oppo-^ 

 site sides communicate* 

 behind the upper incisors; 

 c, cardiac plexus; d, solar 



plexus ; e, hypogastrlc plexus; /, renal and supra-renal plexus. 1 

 and 2, First and second divisions of fifth cranial nerve ; 3, vagua 

 nerve; 4, first spinal nerve. 



