374 



ANATOMY AND PHYSIOLOGY 



Suprascapular nerve and artery 



The shoulder (and whole upper extremity) is pulled forward 



by the action of the anterior 

 serratus on the shoulder blade,, 

 and if this motion is accom- 

 panied by a sudden forcible 

 extension of the arm and fore- 

 arm, that is " striking out from 

 the shoulder." 



REVIEW NOTES CONCERNING 

 THE EXTREMITIES 



The upper extremity 

 From the shoulder down, the 

 anterior surface is the flexor 

 surface, and the posterior is 

 the extensor surface of the 

 extremity. 



Arm. Anterior. The bi- 

 ceps muscle, with the median 

 nerve and brachial vessels on 

 its medial border. Posterior. 

 Triceps muscle, with radial 

 nerve in the groove between 

 the two humeral heads. 



Forearm. Anterior (Fig. 

 240). Superficial flexor mus- 

 cles and the round pronator 

 from the internal epicondyle. 

 Deep flexor muscles from shafts 

 of the radius and ulna, and 

 median nerve between the su- 

 perficial and deep groups. 

 Posterior. Extensor muscles 

 and the short supinator from 

 the external epicondyle. La- 

 teral or radial side, brachio- 

 radialis from the external 

 epicondylar ridge. 



br 



Posterior 

 interosseous 



FIG. 241. THE ARM AND FOREARM 

 'POSTERIOR. 



