PESISECEION OF THE WVECK, . Ft 
branch from the 2d thoracic spinal nerve. Shortly 
after emerging from the vertebral canal these nerves 
branch to form a complicated plexus, represented in 
Fig. 7, from which branches are given off to the 
arm, fore-arm, shoulder, etc. ‘The plexus should be 
dissected upon the side the least injured by previous 
dissection; in this case probably the right side. Cut 
TO CLAVO-DELTOID 
Vi SUPRA-SCAPULAR 
aa SUB-SCAPULAR 
VII MUSCULO-CUTANEOUS 
CIRCUMFLEX 
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Fic. 7.—DIAGRAM OF THE BRACHIAL PLEXUS OF THE Doc. 
carefully through the muscles on the side of the verte- 
bral column where the neck and thorax meet until some 
of the nerves are exposed, and then from this trace 
out the other members of the plexus. In order to 
expose the plexus fully one must take great care not 
to cut small branches, and must dissect slowly. The 
following are the chief terminal branches of the plexus. 
From which of the spinal nerves they are derived can 
be seen from the figure, although the arrangement of 
the plexus varies somewhat in different individuals. 
a. Branch distributed chiefly to the clavo-deltoid. 
