BRACHIAL PLEXUS OF NERVES IN MAN 315 



ulnar fasciculus will be given in connection with the ulnar 

 nerve. 



Those plexuses within each group in which branches from the 

 seventh cervical (the intermediate trunk) contribute to the 

 medial fasciculus I have classified as cephalic types and those in 

 which a branch from the caudal trunk goes to the lateral fascic- 

 ulus either directly or by joining the seventh cervical nerve I 

 have classified as caudal types. 



Group 1 is in this way subdivided into three subgroups; group 

 2 into two subgroups, and group 3 into two subgroups. The 

 types in group 1, I have classified A, B, and C. Type B (fig. 1) 

 is the typical arrangement described above. Type A is the most 

 cephalic and type C the most caudal. In all of these in group 

 1 the fourth cervical nerve sends a branch to the plexus. 



Type A 



Type A is distinguished by having a ventral branch from the 

 intermediate trunk (seventh cervical nerve) to the medial 

 fasciculus of the plexus so that this contains fibers from the 

 seventh and eighth cervical and first thoracic nerves (fig. 5). 

 The lateral fasciculus contains fibers from the fourth, fifth, sixth 

 and seventh cervical nerves. The plexuses of this type are the 

 most cephalic of the whole series. There are five cases of this 

 type or 2.85 per cent of the 175 plexuses. In one of the cases the 

 branch from the caudal trunk to the dorsal fasciculus is from the 

 eighth cervical nerve alone, so that the dorsal fasciculus has no 

 branch from the first thoracic. 



Type B 



In type B the lateral fasciculus contains fibers from the fourth, 

 fifth, sixth and seventh cervical nerves and the medial fasciculus 

 fibers from the eighth cervical and first thoracic. There are 101 

 cases of this type, or 57.71 per cent of the 175 plexuses, that is, 

 more than half the total number of plexuses are of type B (fig. 1). 



Type C 



Type C differs from the preceding in that there is a branch 

 from the caudal trunk to join the seventh cervical nerve or the 



