MEDIAN NEEVE PAEALYSIS. 237 



It will thus be seen that when the ulnar nerve is entirely 

 paralysed there is loss of sensation over the ulnar half of palm, 

 the hypothenar eminence, the ulnar half of the back of the hand, 

 and the whole of the palmar and dorsal aspects of the little finger 

 and the ulnar half of the ring finger. 



Later in the course of ulnar nerve paralysis trophic changes 

 occur in the same area. 



It is important to recollect that if the ulnar nerve is cut 

 just above the wrist perhaps the most usual spot the dorsal 

 cutaneous branch may escape any injury, and the patient will 

 therefore retain sensation on the back of the ring and little 

 fingers as low as the middle of the second phalanx, but below 

 this the skin will be anaesthetic. 



Articular. 



In arm To elbow joint. 



In foreman To wrist and carpal joints. 



In hand To ulnar two carpo-metacarpal joints. 



To metacarpo-phalangeal and interphalangeal 

 joints of ring and little fingers. 



In paralysis of the nerve, trophic changes may occur in the 

 small distal joints leading to a condition akin to ordinary osteo- 

 arthritis. 



The median nerve, arising by two heads, one from the outer 

 and the other from the inner cord of the brachial plexus, runs a 

 median course down the arm, crossing the brachial artery at its 

 middle, as a rule superficially but sometimes deeply, from without 

 inwards. 



It gives off no branches in the arm. 



At the bend of the elbow it lies under cover of the bicipital 

 fascia and internal to the brachial artery. It is not often 

 wounded in the arm or at the bend of the elbow. The nerve 

 enters the forearm between the two heads of the pronator radii 

 teres, and it is possible for it to be compressed by this muscle 

 during violent exercise such as tennis playing, but being deeply 

 placed it is little exposed to actual division until it reaches the 

 lower fourth of the forearm. It is here much more superficial, 



