344 ' ABRAM T. KERR 



fifth, sixth, seventh in 1. It will be noted then that in 82 in- 

 stances or in every plexus but one, the fifth cervical may send 

 fibers to the subclavius; that the fourth cervical may enter in 

 47; the sixth in 44; and the seventh but once. In 39 instances 

 the fibers may come from the fifth or fourth and fifth cervical 

 nerves where the fourth enters the plexus, and in 42 cases the fibers 

 may come from the fifth and sixth, or the fourth, fifth and sixth 

 cervical nerves where the fourth enters the plexus. 



THE CUTANEOUS NERVES TO THE MEDIAL SIDE OF THE ARM 



The cutaneous nerves to the axillary fossa and its borders and 

 the nerves to the skin of the medial side of the arm and the 

 contiguous regions on the dorsomedial and ventromedial side 

 of the arm are derived from several different sources. The nerves 

 to the axillary region are mostly derived from the lateral cutane- 

 ous branches of the intercostal nerves, usually the second, and 

 third, but at times the first and fourth contributing and also 

 branches from the medial brachial cutaneous and the medial 

 antibrachial cutaneous nerves or a separate nerve from the 

 plexus arising independently. The medial side of the arm distal 

 to the axilla and the adjoining dorsal and ventral regions is sup- 

 plied mostly by the medial brachial cutaneous and intercosto- 

 brachial nerves. This latter coming usually from the second 

 intercostal nerve occasionally from one of the others. There 

 are also at times branches to this region of the arm derived from 

 the medial antibrachial cutaneous nerve or an independent nerve 

 that perhaps should be called a second medial brachial cutane- 

 ous. In addition, there are branches to the adjoining dorsal 

 region derived from the axillary and radial nerves, with these 

 latter I shall not deal now. It has been extremely difficult to 

 get satisfactory student records of the distribution of the nerves 

 of this region, even when the dissections were most excellent and 

 the peripheral attachments of the nerves were not disturbed. The 

 nerves here, however, were so frequently loosened that their 

 exact distribution was difficult to verify. For the above reasons 

 it was often difficult when there were several branches from the 

 plexus to determine definitely how they should be named. In 



