BRACHIAL PLEXUS OF NERVES IN MAN 327 



and that there may not be fibers from the nerves cephaHc to 

 the seventh cervical. The 5 cases in which the lateral fasciculus 

 does not give off the ulnar until after it has joined the medial 

 fasciculus or the medial head of the median are included here 

 also. 



There are 92 satisfactory records of the ulnar nerve among the 

 group 1 type of plexus. In 52 of these or 57.28 per cent of the 

 group the fourth, fifth, sixth, seventh and eighth cervical and 

 the first thoracic nerves may take part in the formation of the 

 ulnar nerve. In eleven cases, 11.95 per cent of the group, the 

 seventh and eighth cervical and first thoracic nerves may send 

 fibers to the ulnar nerve and in 29 plexuses, 31.52 per cent of the 

 group, the eighth cervical and first thoracic only send fibers to 

 the ulnar nerve. 



There are 47 satisfactory records of the ulnar nerve among the 

 plexuses of group 2. In 14 of these, 29.78 per cent of the group, 

 the fifth, sixth, seventh and eighth cervical and first thoracic 

 nerves may take part in the formation of the ulnar nerve. In 4 

 cases, 8.51 per cent of the cases, the seventh and eighth cervical 

 and first thoracic alone may send fibers to the ulnar nerve and 

 in 29 plexuses, 61.70 per cent of the group, the eighth cervical 

 and first thoracic nerves alone may send fibers to the ulnar nerve. 



There are 6 satisfactory records of the ulnar nerve among 

 the group 3 plexuses. In 2 of these, 33.33 per cent of the group, 

 the fifth, sixth and seventh cervical nerves in addition to the 

 eighth cervical and first thoracic nerves may take part in the 

 formation of the ulnar nerve. In 1 case, 16.66 per cent of the 

 group, the seventh and eighth cervical and first thoracic nerves 

 send fibers to the ulnar nerve and in 3 plexuses, 50 per cent 

 of the group, the eighth cervical and first thoracic nerves alone 

 make up the ulnar nerve. 



It will be seen from the above that in the most cephalic group 

 of plexuses there is a relatively greater percentage of the group 

 in which in addition to the eighth cervical and first thoracic 

 nerves, the fourth, fifth, sixth and seventh cervical nerves may 

 also take part in the formation of the ulnar nerve and in the 

 more caudal type, that is, groups 2 and 3, a relatively greater 



