On the distribution of the cutaneous nerves etc. 301 



In the hand from which fig. 1 was taken I could not follow any 'of the 

 twigs on to the dorsal surface, but in most of the other cases I found 

 twigs which would amply account for the loss of sensation depicted in 

 Létiévant's figure. In three cases I traced particularly strong branches 

 under the thumb nail and found them ramifying in the bed of the nail. 

 This arrangement is shown in fig. 2. The twigs from the median passed 

 in these cases under cover of a ligamentous band and wound round 

 the ungual phalanx, keeping close to the bone, to reach the dorsal 

 surface. 



In fig. 1 a twig from the external cutaneous branch of the musculo- 

 spiral is shown crossing the branches of the ulnar nerve; in two of 

 the other five cases dissected under water this nerve communicated 

 with branches of the radial just below the wrist-joint. In two others 

 its distribution was much more extensive. In one case it reached the 

 metacarpo-phalangeal articulation of the little finger and communicated, 

 in this situation, with one of the branches of the ulnar nerve. In the 

 other example it was as large as one of the ordinary dorsal digital 

 branches of the ulnar nerve and it supplied the skin on the dorsal 

 surface of the base of the proximal phalanx of the ring finger and 

 extended on the little finger as far as the base of the middle phalanx 

 of that digit. In Létiévant's case of section of the musculo -spiral 

 nerve (above referred to) the little finger may therefore have re- 

 ceived a partial supply from the external cutaneous branch of the 

 musculo -spiral. 



A twig of the musculo- cutaneous nerve was in one case found 

 crossing the branches of the radial on the back of the hand. It is 

 well known that the musculo -cutaneous nerve communicates with the 

 radial on the back of the wrist; in one subject I found large branches 

 joining the branch of the radial which supplies the radial side of the 

 thumb and another considerable branch joining the division of the 

 radial which bifurcates to supply the adjacent sides of the thumb and 

 index finger. These communications from the musculo-cutaneous were 

 proportionally of sufficient size to have taken a considerable part in 

 the sensory supply of the dorsum of the thumb and possibly of the 

 index finger also. Dr. David Hepburn has recorded a case in which 

 the musculo-cutaneous nerve constituted the sole supply of the radial 



