BRACHIAL PLEXUS OF NERVES IN MAN 367 



intermediate trunks. In 3 of these it comes from a stem common 

 to it and the axillary subscapular nerve. In one other case it 

 gives off a small branch to supply the teres major muscle which 

 is also supplied by the axillary subscapular. 



In 10 plexuses the nerve comes from the dorsal division of the 

 intermediate trunk, that is the seventh cervical nerve (fig. 15). 

 In one of these it does not arise directly but comes from a branch 

 that forms one of the heads of the axillary nerve. 



The nerve arises in 4 cases by two roots, one from the dorsal 

 division of the cephalic trunk and one from the dorsal division 

 of the intermediate trunk (fig. 18). In one of these the stem 

 formed by the union of the two roots gives origin also to the 

 subscapular nerve and in another case to the axillary subscapular. 



In 3 cases it arises from the dorsal division of the cephalic 

 trunk. One of these gives off a branch that joins the axillary 

 subscapular nerve. 



The thoracodorsal nerve arises from the cord formed by the 

 union of the dorsal divisions of the intermediate and caudal 

 trunks in 6 instances (fig. 7), and in another it arises by two roots, 

 one from the dorsal division of the intermediate trunk and one 

 from the dorsal division of the caudal trunk. In one case the 

 nerve arises from the dorsal division of the caudal trunk. 



In 115 cases, or 71.42 per cent of this series, no nerve that 

 enters the plexus can be excluded from sending fibers to the 

 thoracodorsal nerve. In 73, the spinal nerves from the fourth 

 cervical to the first thoracic inclusive enter the plexus and in 

 35 from the fifth cervical to the first thoracic. In one case all 

 of the nerves from the fourth cervical to the eighth cervical and 

 in 2 others from the fifth to the eighth. 



In 14 cases the nerves from the fourth to the seventh cervical 

 may contribute, in 8 from the fifth cervical to the seventh. In 

 3 instances the fifth and sixth cervical nerves; in 10 the seventh 

 cervical; in 7 the seventh and eighth cervical and first thoracic; 

 in one the eighth cervical and first thoracic are the nerves that 

 may send fibers to the thoracodorsal nerve. 



Herringham, from his study of 42 plexuses, found that the 

 seventh cervical alone sent fibers to the thoracodorsal nerve in 



