NERVE INJURIES 189 



irreparable damage. This is the pathology of 

 " trophic lesions." 



We pass from the effects of total nerve section to 

 those of an incomplete division. If less than one- 

 third of the fibres are cut, there may be no symptoms 

 at aU except perhaps pain. In general the sensory 

 disturbance is greater than the motor, except in 

 such a nerve as the musculospiral, even complete 

 section of which may cause no anaesthesia.* Epicritic 

 sense is more affected than protopathic. If any 

 muscular weakness is present, a very characteristic 

 electrical reaction may be obtained, the faradic 

 response being lost, but the galvanic response being 

 brisk, not sluggish, and K.C.C. greater than A.C.C. 

 It will be remembered that with complete division, 

 the galvanic response is sluggish, and A.C.C. is 

 greater than K.C.C. f Pain and mottling of the 

 skin are often more evident with partial than with 

 complete divisions of the nerve. 



REGENERATION. 



Much discussion and research have been devoted 

 in the past decade to clearing up the problem 

 as to how the nerve fibre is reproduced when it has 

 been cut off from its nerve cell and has degenerated 

 in consequence. We know that the fibres peripheral 

 to the section degenerate ; we also know that if the 

 cut ends are brought together, whether at once 



* It is often forgotten that the radial nerve is joined in the 

 forearm by branches of the musculocutaneous. 



t I do not explain these terms, because only an expert would 

 undertake the investigation of the electrical reactions. 



