NERVE INJURIES 185 



(/). Paralysis of sweating in the area supplied. 



(g). Vascular dilatation (transitory). 



{h). Trophic changes, such as glossy skin, onychia, 

 sensitiveness to injury, ulceration, and certain 

 histological changes. 



(i). Wallerian degeneration of the distal part of the 

 nerve cut off from its nerve cell. 



(/). Nissl's degeneration (chromatolysis) of the 

 nerve cells from which the nerve fibres are derived. 



Concerning two of these headings a few words of 

 explanation may be useful. 



The terms epicritic, protopathic, and deep sensibility 

 were introduced by Head and Sherren to denote 

 some very important distinctions, failure to observe 

 which has led to endless mistakes and confusion in 

 the past. 



We may take as an illustration the consequences 

 of section of the ulnar nerve at the elbow. 



Epicritic Sense will be lost over the whole of the 

 little finger, over the ulnar half of the ring finger, 

 and over a corresponding area of the ulnar surfaces 

 and border of the hand, both back and front ; that 

 is to say, over the region described in the anatomy 

 books as supplied by this nerve. In this area the 

 patient will be unable : 



(i.) To detect a light touch ; 

 (ii.) To detect mild ranges of heat or cold ; 

 (iii.) To distinguish two points of an opened 



compass as separate ; and 

 (iv.) His localization will be imperfect. 

 In the glans penis epicritic sense is normally absent. 



Protopathic Sense will be lost over the whole of 



