THE ARM. 



279 



OPERATIONS ON THE ARM. 



Caries or necrosis of the humerus may necessitate operative interference at almost 

 any part of the arm. The same may be said of wounds. In operative procedures 

 it is sometimes desirable to avoid important structures and at others to find them. 



Deltoid 



Long head of triceps 



Outer head of triceps 



Radial (musculospiral) nerve 

 Brachialis anticus 



\KI/IW m 



Superior profunda artery 



Brachioradialis 



Extensor carpi radialis longior 



Extensor muscles of forearm 

 External condyle 



FIG. 291. The radial (muscolospiral) nerve and outer side of arm. 



The important structures run lengthwise, hence transverse incisions are not to be 

 used. Most of the large vessels and nerves pass down the inner side of the arm, 

 hence this region is usually avoided. The bone can readily be reached by an incision 

 downward from the insertion of the deltoid, but no operation is to be done in this 

 region without a thorough familiarity with the course of the musculospiral nerve. 



