THE SPINAL CORD 



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The spinal cells receive a part of every impulse from the 

 sensory nerves, and take part in sending out motor impulses 

 to the various parts of the body. 



500. The white matter. The white matter is made up 

 of nerve fibers which still retain their coverings. In fact, 

 the white matter is simply a huge nerve. The nerve 

 threads of the white matter adjoining the right and left 

 sides of the gray matter are motor threads carrying im- 



FRONT SIDE 



Diagram of the action of each part of the spinal cord. 



pulses from the brain to the cells of the gray matter. The 

 nerve threads outside of these and the threads behind the 

 gray matter are prolongations of the sensory nerves of the 

 body, some of which finally go to the brain, and others 

 connect with the cells of the gray matter of the cord. 



501. Spinal nerves. The spinal cord gives off thirty- 

 one pairs of nerves through openings between the rings 

 of the backbone. Each nerve is made of a sensory 

 and of a motor part which soon unite into a single 

 bundle in which the two kinds of nerves cannot be dis- 



