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PHYSIOLOGY.. 



Sympathetic Nerve Chains 



Sources of the Heart's Nerve Supply. The heart re- 

 ceives its nerves from two sources, the sympathetic system 

 and the vagus (or pneurnogastric) nerves. 



The Sympathetic Nervous System. The sympathetic 

 nervous system consists of two rows of ganglia in the body 

 cavity, one along each side 

 of the spinal column, re- 

 ceiving branches from the 

 spinal nerves, and sending 

 branches to all the 

 internal organs of 

 the body, the 

 heart and lungs in 

 the thorax, and the 

 stomach, intestines, and the 

 other organs of the abdomi- 

 nal cavity. In many places 

 these nerves form a thick 

 network called a plexus. 



One very large plexus is on the dorsal surface of the 



stomach, and is called 

 the solar plexus. 



Fig. 30. Relation of Spinal Cord and 

 Sympathetic Nervous System (Diagram). 



The Vagus Nerves. 



- The vagus nerves 

 are a pair of the cranial 

 nerves arising from the 

 sides of the spinal bulb ; 

 and passing downward, 

 they give branches to 

 the pharynx, the gullet, 



the stomach, the larynx, the windpipe, the lungs, and the 

 heart. Now, whatever other function the vagus nerves 



Sympathetic.. 

 Ganglion 



Fig- 31. Ideal Cross-section of the Nervous 

 System. (After Landois and Stirling.) 



