The Visceral or Splanchnic Division 97 



The visceral division comprises several subdivisions, which may be 

 grouped under three heads. 1. The sympathetic division (or system), 

 so called because it was formerly believed to be capable of reflexes inde- 

 pendent of the cerebro -spinal mechanism. 2. The vagal, cranial, and 

 sacral nerves and ganglia. 3. The ' local ' systems of the alimentary 

 canal. 



1. The sympathetic division comprises the ganglia of the sym- 

 pathetic chains, one chain lying on each side of the vertebral column ; and 

 the collateral ganglia in special relation to the abdominal viscera. 

 There is (on each side) one sympathetic ganglion for each of the spinal 

 nerve roots from the fifth thoracic to the third sacral ; there is one ganglion 

 (the ' stellate ' ganglion) connected with the first four thoracic roots, and 

 two ganglia (the 'inferior and superior cervical') associated with the 

 eight cervical roots. 



Fig. 77. The connection of a spinal nerve with a ganglion of the sympathetic chain. 

 (Quain's Anatomy.) The two rami connecting the sympathetic ganglion with the 

 spinal nerve are shown, and also the two roots of the recurrent nerve which supplies 

 the tissues lying within the spinal canal surrounding the spinal cord. 



There are three collateral ganglia lying near the points at which the 

 large arteries originate from the aorta; these are the superior mesenteric 

 ganglion, the inferior mesenteric ganglion, and the semilunar 14 or solar 

 ganglion. 



The pre-ganglionic fibers of the sympathetic division leave the spinal 

 nerves over the white rami communicantes of each nerve, and some of 

 the post-ganglionic fibers are again given back over the gray rami to the 

 spinal nerves for distribution to various parts of the body. 15 The white 

 rami are largely composed of medullated fibers, and the gray rami are 



14 Not to be confused with the Gasserian ganglion (cranial), which unfortunately 

 is also called the semilunar ganglion. 



15 The majority of the post-ganglionic fibers of the 'sympathetic' division do not 

 return to the spinal nerves, but emerge through the visceral nerves. 



