DISEASES OE THE. N1:R\T)US SYSTEM. 



By M. R. TRUMBOWER, V. S. 



THE AXATOilY AND PHYSIOLOGY OF THE BRAIX AXD NERVOUS 



SYSTEM. 



The nervotis sj'stem may be regarded as consisting of two sets of 

 organs, peripheral and central, the function of one being to establish 

 a eomniunication between the centers and the different parts of the 

 body, and that of the other to generate nervous force. The whole 

 may be arranged under two divisions: First. The cerehi'G-spinal or 

 nervous sj^stem of animal life. Second. The sympathetic, ganglionic, 

 or nervous system of organic life. Each is possessed of its own cen- 

 tral and peripheral organs. 



In the first, the center is made uj) of tv\'o portions, one large and 

 expanded — the brain — i)laced in the cranial cavity; the other elon- 

 gated — spinal cord — continuous with the brain, and lodged in the 

 canal of the vertebral column. The perij)heral portion of this sj'stem 

 consists of the cerebro-spinal nerves, which leave the axis in symmet- 

 rical pairs, and are distributed to the skin, the voluntary muscles, 

 and the organs of common and spinal sensation. 



In the second, the central organ consists of a chain of ganglia con- 

 nected by nerve cords, which extends from the head to the rump of 

 each side of the spine. The nerves of this sj'stem are distributed to 

 the in voluntar}'- muscles, mucons membrane, viscera, and blood-vessels. 



The two systems have free intercommunication, ganglia being at 

 tiic junctions. 



Two substances, distinguishable by their color, enter into the for- 

 mation of nervous matter, viz. , the w^hite or medullary, and tlie gray 

 or cortical substance. Both are soft, fragile, and easil}' injured, in 

 consequence of wliich the principal nervous centers are always well 

 protected bj" bony coverings. The nervous substances present two 

 distinct forms — nerve fibers and nerve cells. An aggregation of nerve 



cells constitutes a nerve ganglion. 



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