DISEASES OF THE NERVOUS SYSTEM. 
By M. R. TrumBoweEsg, V.S. 
[Revised by John R. Mobler, A. M., V. M. D.J 
ANATOMY AND PHYSIOLOGY OF THE BRAIN AND NERVOUS 
SYSTEM. 
(Pl. XIX.) 
The nervous system may be regarded as consisting of two sets of 
crgans, peripheral and central, the function of one being to estab- 
lish 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 
system; second, the sympathetic or ganglionic system. Each is 
possessed of its own central and peripheral 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 
elongated (spinal cord), continuous with the brain, and lodged in 
the canal of the vertebral column. The peripheral portion of this 
system consists of the cerebrospinal nerves, which leave the axis 
in symmetrical pairs and are distributed to the skin, the voluntary 
muscles, and the organs. 
In the second, the central organ consists of a chain of ganglia, 
connected by nerve cords, which extends on each side of the spine 
from the head to the rump. The nerves of this system are dis- 
tributed 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, namely, the white 
or medullary and the gray or cortical substance, enter into the for- 
mation of nervous matter. Both are soft, fragile, and easily injured, 
in consequence of which the principal nervous centers are 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 peripheral end 
organs. The nerve cells, however, besides transmitting impulses, 
act as physiological centers for automatic, or reflex, movements, 
and also for the sensory, perceptive, trophic, and secretory functions. 
A nerve consists of a bundle of tubular fibers, held. together by a 
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