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  Section: Anatomy of Vertebrate Animals » The Muscles and the Viscera
 
 
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The Sympathetic

 
     
 

A Sympathetic Nervous System has been observed in all the Vertebrata except Amphioxus and the Marsipobranchii. It consists, essentially, of two longitudinal cords, placed one upon each side of the inferior face of the cranio - spinal axis. Each cord receives communicating fibres from the spinal nerves of its own side, and, when complete, from all the cranial nerves except those of the special senses of hearing, sight, and smell - the Vidian nerves constituting the anterior terminations of the sympathetic cords. At the points of communication ganglia are developed, and the nerves which emerge from these ganglia are distributed to the muscles of the heart and vessels, and to those of the viscera. These peripheral nerves of the sympathetic system frequently present small ganglionic enlargements.

In the Marsipobranchii, the place of the sympathetic appears to be taken, to a great extent, by the pneumogastric; and, in Myxine, the two pneutnogastrics unite upon the intestine, and follow it, as a single trunk, to the anus.


 
     
 
 
     



     
 
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