BRACHIAL PLEXUS OF NERVES IN MAN .'M5 



these cases the nerves were classified and named as carefully 

 as possible at the time the record was verified but as the dis- 

 section of the plexus came much later than the working out of 

 the peripheral distribution, the exact area supplied by each 

 branch from the plexus could not always be determined. 



THE MEDIAL BRACHIAL CUTANEOUS NERVE 



The medial brachial cutaneous nerve (lesser internal cutane- 

 ous or nerve of Wrisberg) is usually described as rising from the 

 medial trunk of the brachial plexus. My records are complete 

 and satisfactory for 166 plexuses. In 137, or in 82.59 per cent, 

 it is represented by a single branch and in 28 plexuses it is given 

 off as two branches and in 1 as three separate filaments. In 

 addition to this there are 9 cases in which there is recorded a 

 branch given off by the medial antibrachial cutaneous nerve 

 near its origin that anastomoses with the intercostobrachial. 

 I am inclined now to classify all these as accessory medial brachial 

 cutaneous nerves. 



As this nerve and its branches are very small and as they 

 are imbedded in a considerable mass of connective tissue it must 

 be remembered that there is great danger of breaking or entirely 

 overlooking and cutting away small accessory and communi- 

 cating branches. This report is then positive for the branches 

 and connections found and recorded, but it is not negative for 

 those not recorded. There were undoubtedly other cases in 

 which there was more than one nerve which supplied the region 

 usually assigned to the medial brachial cutaneous nerve. There 

 is much need of more very careful study of the interrelations of 

 this nerve, the intercostobrachial, the posterior brachial cutane- 

 ous branch of the radial, and the cutaneous branches from the 

 medial antibrachial cutaneous nerve which supply the medial 

 and dorsal surfaces of the arm. 



Of the 137 specimens in which the nerve arises as a single branch 

 it comes directly and separately from the caudal trunk or medial 

 fasciculus of the plexus in 92 (fig. 3) and from the dorsal division 

 of the caudal trunk in 2 (fig. 7). In 11 other cases it arises 

 separately, in 6 from the first thoracic nerve, in 4 from the ulnar 



