186 NERVE INJURIES 



the little finger, and over a small area of the ulnar 

 border of the hand. In this region the patient will 

 be unable to detect : 

 (i.) A pin prick ; 

 (ii.) Extremes of heat and cold. 



Deep Sensibility will be lost over a smaller area 

 still, of variable dimensions. That is to say, deep 

 pressure will no longer be appreciated by the nerve 

 endings in the tendons, joints, and bones. 



It is easy to deduce from the above that serious 

 pitfalls await the unwary observer in testing such a 

 case. He may make pressure on the little finger over 

 the metacarpo-phalangeal joint, or over the ulnar 

 border of the ring finger, and on being told by the 

 patient that both are readily felt, may conclude quite 

 incorrectly that the ulnar nerv^e is intact. Testing 

 with a pin point will probably bring out an area of 

 anaesthesia smaller than that currently supposed to 

 be supplied by the ulnar nerve. 



The only reliable method of testing for ancBsthesia 

 in such cases is to make the patient close the eyes, and 

 ask him to indicate with a finger of the opposite 

 hand each point touched as lightly as possible by a 

 pencil of wool. In testing hairy parts, the hairs 

 should be shaved, or protopathic or deep sensibility 

 may be excited. If these directions are followed, an 

 area of anaesthesia will be mapped out corresponding 

 to the anatomical distribution of the nerve. 



It is astonishing, at first sight, to find that a 

 patient can feel a pin-prick or pressure in a region 

 to which the anatomist can trace only one nerve, 

 and that one known to be divided. By what path 



