THE BRACHIAL PLEXUS. 



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lower trunk, formed by the union of the eighth cervical and first dorsal, passes 

 down on the inner side of the axillary artery in the middle of the axilla, and 

 forms the inner cord of the brachial plexus. The posterior divisions of the upper 



FIG. 498. Cutaneous nerves of right upper 

 extremity. Anterior view. 



FIG. -199. Cutaneous nerves of right upper 

 extremity. Posterior view. 



trunk (formed by the junction of the fifth and sixth nerves) and of the middle 

 trunk (the seventh nerve) unite together to form the posterior cord of the brachial 

 plexus, which is situated behind the second portion of the axillary artery. From 

 this posterior cord are given off the two lower subscapular nerves, the upper sub- 

 scapular nerve being given off from the posterior division of the outer trunk 

 prior to its junction with the posterior division of the middle trunk. The pos- 

 terior cord divides into the circumflex and musculo-spiral nerves. The musculc- 



