DISSECTION OF THE NECK. 



71 



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. Cat 



TO CLAVO-DELTOID 

 SUPRA-SCAPULAR 



3 SUB-SCAPULAR 

 MUSCULO-CUTANEOUS 



CIRCUMFLEX 



JMUSCULO-SPIRAL 



EDIAN 

 ULNAR 



* ^S^RES MAJOR 



'fOOs 



Fig. 7. — Diagram of the Brachial Plexus of the Dog. 



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. 



