BRACHIAL PLEXUS OF NERVES IN MAN 373 



cutaneous nerve arises from the medial fasciculus of the plexus 

 and in over 10 per cent from the caudal trunk. 



54. In over 97 per cent of the cases both the eighth cervical 

 and first thoracic nerves may send fibers to the medial antibra- 

 chial cutaneous nerve. 



55. The medial anterior thoracic nerve arises from the medial 

 fasciculus in over 69 per cent of the plexuses and from the caudal 

 trunk in over 24 per cent. 



56. Both the first thoracic and the eighth cervical may send 

 fibers to the medial anterior thoracic in over 95 per cent of the cases. 



57. The lateral anterior thoracic nerve arises from two roots 

 in over 54 per cent of the plexuses, by one root in over 23 per 

 cent and by three roots in nearly 20 per cent. 



58. In over 43 per cent of the cases where there is a single 

 root for the lateral anterior thoracic nerve, this comes from the 

 lateral fasciculus of the plexus. In over 78 per cent of the cases 

 where there are two roots, one of them comes from the ventral 

 divisioil of the cephalic trunk and the other from the ventral 

 divisioji of the intermediate trunk (seventh cervical nerve) 

 before these join to form the lateral fasciculus. In ovei- 54 

 per cent of the cases where there are three roots one arises from 

 the ventral division of the cephalic trunk and the other two from 

 the ventral division of the intermediate trunk of the plexus. 



59. In over 52 per cent of the cases the fourth to the seventh 

 cervical nerves can none of them be excluded from the lateral 

 anterior thoracic nerve and in over 30 per cent, .the fifth to the 

 seventh. All of the nerves cephalic to the eighth cervical nerve 

 may send fibers to the lateral anterior thoracic nerve in over 83 

 per cent of the cases. 



60. The radial nerve arises as one of the terminal divisions of 

 the plexus in over 79 per cent of the cases. In the other cases 

 the radial nerve is formed by the union of two heads. 



61. In 63 per cent the fourth cervical to the first thoracic 

 nerves can none of them be excluded from the radial nerve and 

 in over 34 per cent the fourth cervical to the first thoracic can 

 not be excluded, that is, in 97 per cent of the plexuses none of 

 the nerves that entered the plexus can be excluded. 



