BRACHIAL PLEXUS OF NERVES IN MAN 331 



in 54 instances, or 35.52 per cent. In 10 cases this branch comes 

 from the seventh cervical nerve, in 4 of them dividing and send- 

 ing a subdivision to the uhiar nerve as the lateral head of the 

 ulnar (fig. 10), and in 6 of them remaining undivided (fig. 19). 



In 40 of the cases, the branch to the medial head of the median 

 arises from the lateral fasciculus of the plexus. In 24 of these 

 the branch divides into two parts sending one of the subdivisions 

 to the ulnar nerve as the lateral head of the ulnar (figs. 1 and 3). 

 In 1 of these instances it divides into three branches, one going 

 to the ulnar, one to the lateral head of the median, and the third 

 to the medial head of the median nerve, in one of these giving 

 off in addition a branch to the coracobrachialis muscle (fig. 24) , 

 In another of the above instances, the lateral head of the ulnar, 

 in addition to sending fibers to the ulnar and medial head of the 

 median, gives off two branches that join the lateral head of the 

 median. In a third case, in addition to a lateral head of the 

 ulnar as above, there is an additional branch from the lateral 

 fasciculus to the medial head of the median. 



In 16 instances, the extra branch to the medial head of the 

 median does not divide but goes to the medial head of the 

 median only (fig. 20). In the 4 remaining instances, the branch 

 to the medial head of the median nerve arises from the lateral 

 head of the median, in 1 giving off the lateral head of the ulnar 

 (fig. 8), and in 2 going to the medial head of the median only 

 (fig. 21), and in 1 sending a branch to the lateral head as well 

 as the medial head of the median nerve. 



In only one instance is there a branch given off from the 

 medial head of the median nerve. This branch goes to the 

 coracobrachialis muscle (fig. 4), and may receive its fibers from 

 the seventh cervical nerve since there is a branch from this to 

 join the medial fasciculus of the plexus from which the medial 

 head of the median nerve arises. 



The lateral head of the median gives off a lateral branch or 

 branches in 26 plexuses, 4 of these have already been noted 

 where this branch goes to the medial head of the median. In 

 20 of the remaining 22 instances, the branch connects with the 

 ulnar nerve as the lateral head of the ulnar, as in figure 2. In one 



