DISEASES OF THE NERVOUS SYSTEM. 



By M, R. TRUMBOWER, V. S. 



THE ANATOMY AND rHYSIOLOGY OF THE BRAIN AND NERVOUS 



SYSTEM. 



The uerv^ous system may be regarded as consisting of two sets of 

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

 communication 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 cerebrospinal or nervous sys- 

 tem of animal life. Second. The sympathetic, ganglionic, or nervous 

 system of organic life. Each is possessed of its own central and periph- 

 eral organs. 



In the first, the center is made up of two portions, one large and 

 expanded— the brain — placed in the cranial cavity; the other elon- 

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

 of the vertebral column. The peripheral portion of this system consists 

 of the cerebro-spinal nerves, which leave the axis in symmetrical 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 on 

 each side of the spine. The nerves of this system are distributed to the 

 involuntary muscles, mucous membrane, viscera, and blood-vessels. 



The two systems have free intercommunication, ganglia being at the 

 junctions. 



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

 tion of nervous matter, viz, the white or medullary, and the gray or 

 cortical substance. Both are soft, fragile, and easily injured, in con- 

 sequence of which the principal nervous centers are always well pro- 

 tected by bony coverings. The nervous substances present two dis- 

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

 constitutes a nerve ganglion. 



The nerve fibers represent a conducting apparatus, and serve to 

 place the central nervous organs in connection with i)eripheral end 



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