328 ABRAM T. KERR 



percentage of each group in which only the eighth cervical and 

 first thoracic nerves enter and the more cephalic nerves take 

 no part in the formation of the ulnar nerve. 



Wichmann ('00) has tabulated from the notes of Renz the 

 reports of 24 writers on 171 cases, showing the spinal nerves that 

 contribute to the formation of the ulnar nerve. ^ Since then, 

 Schumacher ('08) has reported on 10 more investigated by him. 

 If my 145 plexuses are added to these we have a total of 326 cases. 



The eighth cervical and first thoracic contribute to the ulnar 

 nerve in 103 cases or 31.28 per cent, Wichmann 41, Schumacher 1, 

 Kerr 61. 



The seventh and eighth cervical and first thoracic nerves send 

 fibers to the ulnar nerve in 114 cases or 35.27 per cent, Wichmann 

 89, Schumacher 9, Kerr 16. 



In addition to the eighth cervical and first thoracic nerves 

 the ulnar may receive a contribution from the fifth, sixth and 

 seventh cervical nerves in 87 cases or in 26.68 per cent, Wichmann 

 19, Kerr 68. The fourth cervical nerve also cannot be excluded 

 in 52 of these from my series. 



In Wichmann's tabulation there are 22 additional cases in 

 which the ulnar nerve is formed in some other way. It arises 

 from the eighth cervical nerve in 3 instances, from the seventh 

 and eighth in 3, from the sixth, seventh and eighth in 10 and 

 from the fifth, sixth, seventh and eighth in 6. 



From the above it will be seen that the ulnar nerve receives 

 fibers from one or more of the nerves cephalic to the eighth cervi- 

 cal in 220 plexuses or in 67.48 per cent of the 326 cases. In the 

 above tabulation I have excluded the 31 cases in which there is 

 a branch to the medial head of the median. In some of these I 

 feel sure the ulnar also receives fibers from this branch. 



JTHE MEDIAN NERVE 



The median nerve is usually described as formed by the 

 union of two branches, one from the medial and one from the 

 lateral fasciculus of the brachial plexus, the medial and lateral 



'' In Wiohinann's tabulation he has credited Walsh 101 cases, 27 of these are 

 apiiarentl}' erroneously credited and should have been credited to some one else. 



