406 NAVIN ON THE HOESE. 



The eiglitli jpair^ called par vagum, is divided into many 

 branches, which are sent to many muscles of the head and 

 neck, to the windpipe, the gullet, the lungs, the heart, the 

 stomach, etc. 



The ninth ixdr are principally sent to the muscles of the' 

 tongue. 



The tenth i)air are distributed to the muscles of the head 

 and neck. 



The nerves given off from the spinal cord are thirty-six 

 pairs. They are all nerves of motion and sensation, or feel- 

 ing. One pair is given off at each bone of the spine, seven 

 from the neck, eighteen from the back, five from the loins, 

 and five from the sacrum, or rump-bone, and one pair from 

 the coccyx, or tail-bones. 



The nerves are sent, by their branches, to every muscle 

 of the trunk and limbs, and through them there is a com- 

 munication with the brain. 



In addition to these nerves, there is one great system, 

 called the sym])athetic nerve. This is a very extensive nerve, 

 communicating with all the internal parts, and with the 

 head, neck, chest, quarters, and abdomen, or belly. It com- 

 municates very freel}^ with the other nerves. It brings all 

 parts of the system in sympathy with each other. 



Some nerves are under the control of the will, and called 

 voluntary nerves. Some, called involuntary nerves, act en- 

 tirely independently of the will. Some are only partially 

 under the control of the will. The nerves which supply the 

 muscles of the limbs are examples of voluntary nerves. 

 Those which supply the heart, car, and bowels are examples 

 of involuntary nerves. Those concerned in breathing are 

 partially under the will. 



