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. Cut 



TO CLAVO-DELTOID 

 SQPRA-SCAPULAR 



SUB-SCAPULAR 

 3 MUSCULO-CUTANEOUS 

 CIRCUMFLEX 



D MUSCULO-SPIRAL 



MEDIAN 

 ULNAR 



MAJOR 



'fOUs 



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



