BRAIN AND NERVOUS SYSTEM. . 331 



foot can neither feel nor move. In this state we try in vain 

 to walk, for the muscles cannot act ; and if we strike the 

 foot, we feel no pain ; but when the pressure is removed, and 

 the communication restored, sensibility returns to the foot, 

 and the power of contraction to the muscles. 



757. Most of the nerves of sensation and of motion do not 

 pass directly from the brain to the trunk and the extremities, but 

 from the spinal cord. (Fig LXV. e, e, c, e.) The upper part of the 

 cord sends nerves to the arms, and to the chest and its organs, 

 the heart and the lungs. The middle part supplies the ab- 

 domen, and the lower part supplies the lower limbs. These 

 several organs and parts of the body hold their communica- 

 tion with, and receive their nervous life from, the brain, 

 through this nerve, or rather bundle of nerves, in the back- 

 bone, and the branches which pass from it. 



758. There are thirty pairs of nerves, or branches, which 

 .go from tliis cord to the body and the limbs. These parts 

 must not only have free nervous connection with the spinal 

 cord, but, through the cord, they must have uninterrupted 

 communication with the brain. If this communication be 

 interrupted or broken off in the cord, all the parts of the 

 body which are supplied with nerves from it, below the point 

 of obstruction, will be deprived of their power of sensation 

 and motion. This palsy of the muscles or parts of the body, 

 and interruption of the regular operatipns of the organs, 

 happen occasionally from such accidents to the spine as pro- 

 duce pressure upon its great nerve, and sometimes from dis- 

 tortion, or curvature, which, in a lesser degree, produce the 

 same effect upon the cord. 



759. Mr. J. fell, in the year 1830, and struck the hollow 

 of his back on some stones, and injured the spine about the 

 middle of the back. The cord was injured or pressed at that 

 point, and free communication between the lower parts of the 

 cord and the brain interrupted. All the parts of the body 

 below the injury were palsied. But the power of motion and 

 of sensation was restored as the cord recovered from the 

 effects of the accident, and' the pressure was removed, or the 



