THE NERVOUS SYSTEM OF MAN. 63 



consciously and may be moved voluntarily; but the 

 whole lower portion, including the legs, is paralyzed 

 both to conscious sensation and to voluntary motion, 

 because these parts are cut off from the cerebral center. 

 But reflex movements remain. 



3. Cut the posterior root of a spinal nerve. Now 

 all that part to which this nerve is distributed is para- 

 lyzed to sensation, but may be voluntarily moved. If, 

 on the contrary, the anterior root is cut instead of the 

 posterior, then the part is paralyzed to motion, though 

 not to sensation. If, finally, the nerve is cut below the 

 junction of the two roots, then the part to which the 

 nerve is distributed is paralyzed to both sensation and 

 motion. 



4. Irritate a nerve in its course — say, by pinching it. 

 For example, pinch or strike the ulnar nerve, lying be- 

 tween the elbow joint and the inner condyle. We are 

 all familiar with the fact that we feel pain in the little and 

 ring fingers, where this nerve is distributed. If it were not 

 for the skin covering the nerve, and which of course 

 has its own nerves of sensation — if the skin were cut 

 away so as to bare the nerve and the nerve alone was 

 pinched, the only sensation we should feel would be in 

 the little and ring fingers and that side of the hand. 

 Why ? Because the nerves are distributed there. The 

 intelligence offices are there. Therefore at the head 

 center the painful intelligence seems to be reported from there. 

 How could it be otherwise ? 



5. Cut a nerve, perhaps high up in the arm or leg. 

 Expose the ends. Pinch the end below the cut; you 

 feel nothing. But pinch the end above the cut; you 

 feel pain — but where ? Not at the place pinched, but 

 in the fingers or toes where the cut nerve is distributed 

 — i. e., where the nerve terminals, the intelligence offices, 

 are. In any telegraphic system, if a wire is cut and a 



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