The Nervous System. 267 



of that part still in connection with the cord, the proximal 

 end, produces pain. In course of time degeneration of the 

 nerve and the tracts in the cord supplied by it occurs ; but 

 the proximal, and not the distal, end is the part which 

 undergoes defeneration. If the nerve be divided below its 

 ganglion, then degeneration of the nerve below the ganglion 

 occurs. This is explained by saying that the ganglion is 

 the seat of nutrition of the sensory root. Another result 

 of the division of this root is loss of all feeling in the 

 parts supplied by it. When the inferior or motor roots 

 are cut, movement of the parts with which it is in con- 

 nection occurs ; stimulation of the proximal end produces 

 no movement, whilst stimulation of the distal extremity 

 provokes muscular contraction ; as the result of the 

 section degeneration occurs, not, however, on the spinal 

 cord side of the nerve, but in the distal extremity. On 

 irritating the proximal extremity of the divided motor roots, 

 it has been found in some cases that pain results. This 

 is due to the fact that some sensory fibres are also present 

 in the inferior root, being derived from the superior one after 

 the nerves have joined. The phenomenon is termed 

 recurrent sensibility. 



The function of the inferior or motor roots is to supply 

 all the voluntary muscles with the power of movement, the 

 bladder and uterus with contractile power, dilator and 

 constrictor fibres to the bloodvessels, secretory fibres to the 

 sweat-glands of the skin, and nutritive nerves to the 

 tissues. The spinal sensory fibres supply sensation and 

 touch to the whole of the body, with the exception of 

 certain parts of the face. 



The vaso-motor fibres run in the lateral columns, passing 

 into the ganglia of the grey matter; they leave the spinal 

 cord by the inferior root, and reach the muscular coat of 

 the bloodvessels either by the spinal nerves or the sym- 

 pathetic. Respiratory nerves run down the lateral columns 

 on the same side as the centre from which they originated, 

 and pass through the inferior roots to the motor nerves of 

 the respiratory muscles. 



