DEPENDENCE OF NERVES AND MUSCLES. 47 



We try to stand when the foot is asleep, but we are unable 

 to do so. The brain starts the nerve currents, and they run 

 along the nerve as far as the compressed part ; here they 

 stop. They cannot reach the muscles of the leg below. 

 Hence the muscles do not shorten, and we do not rise, no 

 matter how strongly we will to do so. 



Why is it that the nerves and muscles thus sometimes lose 

 their ability to perform their natural activities ? 



This has been explained by saying that the nerve has lost, 

 for the time, its power of conducting nerve currents, owing 

 to external pressure. But is it not possible that some of the 

 effect of pressure on the limb is indirect rather than direct ? 

 That something beside the nerve has been compressed, and 

 that the apparent inability of the nerve to convey the nerve 

 impulse is, in part, a secondary, and not a primary, effect ? 

 What process in the limb has been interfered with by the 

 pressure due to the position in which one has been sitting or 

 lying ? What is the temperature of the benumbed limb ? 



On what are the nerves and muscles so dependent for the 

 maintenance of their activity ? 



READING. Power through Repose, Call ; The Technique of 

 Rest, Brackett ; Muscles and Nerves, Rosenthal. 



