BRACHIAL PLEXUS OF NERVES IN MAN 337 



THE NERVE TO THE CORACOBRACHIALIS MUSCLE 



In the above description of the musculocutaneous nerve no 

 mention has been made of any of its branches of distribution. 

 The nerve to the coracobrachiaHs muscle is usually described 

 as a branch of the musculocutaneous nerve. In many cases, 

 however, it takes origin from the brachial plexus independent 

 of the musculocutaneous nerve and there may be more than 

 one nerve to the muscle. 



A record of the branches of the musculocutaneous nerve was 

 not made for all of the plexuses of my series, so that I have but 

 109 records of the nerve to the coracobrachialis muscle. 



In 54 plexuses, or 49.54 per cent of the 109 in which there are 

 records, the nerve to the coracobrachialis muscle arises as a 

 branch of the musculocutaneous nerve. There is but -a single 

 branch arising from the musculocutaneous nerve for the muscle 

 in 30 of these cases (fig. 2 and 15). In 2 of the above the mus- 

 culocutaneous arises from the ventral division of the cephalic 

 trunk. In the remaining 24 instances there is more than 1 branch. 

 In 14 of these, there are two separate branches (fig. 25), in 6 of 

 them there are 3 independent branches (figs. 3 and 14) ; and in 

 3 instances there are 4 branches. In one of these last three 

 cases, the musculocutaneous nerve arises from the ventral branch 

 of the cephalic trunk of the plexus, but one of its branches to 

 the coracobrachialis muscle receives shortly after its origin a 

 small branch from the ventral division of the seventh cervical 

 nerve (fig. 18). In the remaining instance in which the nerve 

 to the coracobrachialis arises from the musculocutaneous nerve, 

 the nerve receives soon after its origin a small branch from the 

 medial fasciculus of the plexus and in this case there is a second 

 nerve to the muscle coming from a branch connecting the mus- 

 culocutaneous with the median nerve. 



In the remaining 55 plexuses at least one of the nerves to the 

 coracobrachialis muscle arises from some other branch or di- 

 vision of the brachial plexus than the musculocutaneous nerve. 



In 35 instances, or 32.11 per cent of the 109 plexuses, one of 

 the branches to the coracobrachialis muscle arises from the 

 lateral fasciculus of the plexus. In 19 of these, this is the only 



