THE UPPER EXTREMITY. 67 



Teres major, 320-1 ; Figs. 268-9. (3 22 ~3) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. 



Cut away the outer |x>rtion of the acromion process and expose the supra-spinatus. 



Supra-spinatus, 317 ; Fig. 268. (319) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Subscapularis muscle, 319-20 ; Fig. 269. (321-2) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Carefully raise the supra-spinatus, infra. spinatus, and Subscapularis from the scapula and expose the 

 vessels and nerves passing under them. 



Posterior scapular, 547-8; Fig. 343. (-538) 



Branches : Supraspinous. Infraspinous branches. Subscapular branches. 

 Suprascapular artery, 546 ; Fig. 343. (536-7) 



Branches of the suprascapular. 

 Suprascapular nerve, 834. (814-15) 

 Subscapular artery, 555-6-7 ; Fig. 343. (545-6) 



Branches: Dorsal scapular. Infrascapular. 



Chief variations in the Subscapular artery. 



Landmarks of the Arm, Elbow, and Forearm. 

 The Arm, 1186-7-8. (1162-3-4) 

 The shaft of the humerus. Biceps. Brachial artery. 

 Centre of the arm. 

 Brachialis anticus. 

 Median nerve. 

 Ulnar nerve. 

 Musculo-spiral nerve. 



The Elbow, 1188-9-90-1. (1164-5-6-7) 

 Bony points. 



Hollow in front of the elbow. 

 M-like arrangement of the superficial veins. 

 The Forearm, 1193-4-5-6-7. (1168-9-70-1-2) 

 Bony landmarks. 

 Soft parts. Ulnar artery. Ulnar nerve. Median nerve. 



Radial artery. Radial nerve. 



Anterior interosseous artery. 



Posterior interosseous. 



Dissection of the Arm and Forearm. 



Outline the superficial nerve supply of the arm and forearm, Fig. 456 ; P. 836. (817) 



In order to expose the superficial nerves and veins to the best advantage, remove the skin from the arm 

 and reflect it from the forearm. To do this, continue the anterior median incision to the wrist, make a 

 circular incision about two inches below the elbow and remove the skin from the arm above that point. 

 Make a transverse incision at the wrist, reflect the skin of the forearm each way from the median inci- 

 sion to the posterior surface. On the posterior surface, beginning near the elbow, turn it toward the 

 hand to the wrist. The skin of the forearm should not be removed, but preserved as a cover for the 

 muscles after the nerves and veins are exposed, until the dissection of the arm is completed. 



Superficial nerves of the arm and forearm, Fig. 456 ; P. 836. (817) 

 Outer side : 



Posterior division of the circumflex, 835. 



External cutaneous branches of the musculo-spiral, 841. (821-2) 



Upper branch. Lower branch. 

 Musculo-cutaneous, 837-8. (816-17) 



Anterior branch. Posterior terminal branch. 

 Inner side : 



Intercosto-humeral, 845. (825) 



Internal cutaneous branch of musculo-spiral nerve, 841. (821) 

 Lesser internal cutaneous nerve or nerve of Wrisberg, 835-6. (816) 

 Internal cutaneous, 836. 



Anterior branch. Posterior branch. 



