1030 



'THE XERVE 8 Y XT EM 



everv case. 1 The following appears, however, to be the most constant arrangement : 

 above the clavicle (pars snpradavicularis} the fifth and sixth cervical unite soon 

 after their exit from the intervertebral foramina to form a common trunk- The 

 eighth cervical and first thoracic also unite to form one trunk. So that the nerves 



Fio. 760. Cutaneous nerves of right upper 

 extremity Anterior view 



Fro. 701. -Cutaneous nerves of right upper 

 extremity. Posterior view. 



forming the plexus, as they lie on the Scalenus medius at the outer border of the 

 Scalenus anticus muscle, are blended into three trunks an upper one, formed 



1 Kerr, Bardeen, and Kiting, from a study of 175 hrachial plexuses, recognized seven types. In 08 per cent, 

 the outer cord was formed from the fourth to the seventh, the inner cord from the eighth to the ninth spinal 

 nerve, and the posterior or dorsal cord from the fourth to the ninth. In 30 per cent, the outer cord was formed 

 from the fifth to the seventh, the inner cord from the eighth to the ninth, and the posterior cord from the fifth 

 to the ninth. 



