310 ABRAM T. KERR 



in 143 plexuses, or in 81.71 per cent of the 175 studies (fig. 1). 

 In two others, the intermediate trunk, before giving off its ven- 

 tral division, receives a small additional branch from the caudal 

 trunk. In 3 additional plexuses, the lateral fasciculus is formed 

 in the usual way but receives a small additional branch, in 1 

 from the caudal trunk (fig. 8) and in 2 from the eighth cervical 

 nerve (fig. 27). 



In 2 other plexuses, the arrangement differs from the usual 

 in that the ventral division of the intermediate trunk to the 

 lateral fasciculus is given off after the trunk is joined by the dor- 

 sal division from the cephalic trunk (fig. 24). In 4 others the 

 cephalic and intermediate trunks join and this cord then splits 

 into a lateral fasciculus and a branch to the dorsal fasciculus 

 (fig. 21). In the above 6 cases perhaps if more of the con- 

 nective tissue had been, removed from around the nerve they 

 would have corresponded to the usual type. 



In 12 plexuses, the fifth and sixth cervical nerves divide into 

 dorsal and ventral branches and the ventral branches unite to 

 form a cephaloventral trunk which is then joined by the ventral 

 branch of the seventh cervical nerve to form the lateral fasciculus. 

 In 9 of these cases, the fourth cervical nerve joins the fifth before 

 it divides into dorsal and ventral branches. 



There are 2 other cases, similar to the above except that the 

 ventral branch of the sixth joins the undivided fifth cervical and 

 the ventral branch of the cephalic trunk thus formed joins the 

 ventral branch of the seventh cervical to form the lateral fasciculus. 



In 7 cases there is no lateral fasciculus formed. In 4 of these 

 the ventral brq,nch of the cephalic trunk, and in 2 others a trunk 

 formed by the union of the ventral branches of the fifth and sixth 

 cervical divides into musculo-cutaneous and the lateral head of 

 the median nerve (fig. 15). In 6 of the above this latter is 

 joined by the ventral branch of the seventh cervical (fig. 16). 

 In the other case, the ventral branch of the seventh cervical 

 joins the medial head of the median, it corresponds to the lateral 

 head of the ulnar (fig. 15). In the 21 plexuses just described, it 

 is probable that more of the connective tissue was removed than 

 usual and in the last 7 it is not impossible that small connecting 



