BRACHIAL PLEXUS OF NERVES IN MAN 333 



sure from the dissection that any of the nerves which go to make 

 up the brachial plexus did not enter the median nerve. I am, 

 however, reasonably certain that all of them do not contribute 

 in all instances but I have complete records of so few macerated 

 plexuses that I hesitate to quote statistics, since in only 1 of them 

 was there a nerve lacking, the fifth cervical in this case. 



If we assume then that in the other instances of my series all 

 of the nerves that make up the brachial plexus enter the median 

 nerve, we have 174 records. When these are added to the 123 

 instances recorded by Wichmann and Schumacher, we have 297 

 instances in which the fifth, sixth, seventh and eighth cervical 

 and first thoracic nerves send fibers to the median nerve, or 92.52 

 per cent of the 321 records. 



THE MUSCULOCUTANEOUS NERVE 



The musculocutaneous nerve is usually described as formed 

 by the division of the lateral fasciculus of the brachial plexus into 

 the lateral head of the median nerve and the musculocutaneous 

 nerve. 



Since the nerve or nerves to the coracobrachialis muscle so 

 frequently arise from other sources than the musculocutaneous, 

 I have described the branch or branches to this musele separately, 

 and I have regarded the musculocutaneous nerve as complete 

 whether or not it gave off these branches. 



Among the 175 plexuses of my series, the musculocutaneous 

 nerve arises by division of the lateral fasciculus of the plexus 

 into medial head of the median nerve and musculocutaneous 

 nerve in 155 cases, or 88.57 per cent (fig. 1). In two of these 

 the lateral fasciculus of the plexus receives a branch from the 

 eighth cervical nerve. These are of the type C of plexus (fig. 

 28). In another case the lateral fasciculus receives a branch 

 from the medial fasciculus of the plexus, type G of plexus (fig. 

 8) . In these three cases we cannot be sure that the eighth cervical 

 nerve does not send fibers to the musculocutaneous nerve and 

 in the last instance the first thoracic may also. In one of the 

 above 155 cases the musculocutaneous is not complete but the 

 major portion of it arises from the lateral fasciculus and the 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 23, NO. 2 



