DISSECTING MANUAL. 



and between the Brachialis anticus and Brachio-radialis, and 

 divides into the radial and posterior interosseous. In the arm 

 its branches arise in three sets, viz. : on the inner side, behind, 

 and on the outer side of the humerus. [632] 



Internal Branches. The internal cutaneous pierces the fascia 

 high up, internally, and supplies the skin of the arm internally 

 in its upper third, above and behind the area of the lesser in- 

 ternal cutaneous. Muscular branches, in two sets, supply the 

 long head and the inner head of the Triceps; one of the latter 

 (ulnar collateral) accompanies the ulnar nerve to the lower 

 part of the muscle. Posterior branches: Muscular branches, 

 arising in the groove, supply all the heads of the Triceps ; the 

 branch to the inner head runs through it and behind the ex- 

 ternal condyle to the Anconeus. External branches : Two cu- 

 taneous branches arise before it pierces the external intermus- 

 cular septum and pierce the deep fascia below; the superior 

 descends behind the external condyle, supplying the skin on 

 the lower third of the arm, externally and behind, and the up- 

 per half of the back of the forearm; the inferior branch goes to 

 the forearm. Muscular branches, arising between the Brachi- 

 alis anticus and Brachio-radialis, supply them and the Exten- 

 sor carpi radialis longior, and sometimes the brevior. [633] 



Subscapular. All three arise from the posterior cord. The 

 first (short) descends behind the axillary artery to the Sub- 

 scapularis. The second (lower) runs downward and outward 

 behind the axillary artery and below the circumflex nerve 

 to the Teres major; it also sends branches to the Subscapu- 

 laris. The third (long) runs downward and outward between 

 the two preceding, and over the posterior axillary wall with 

 the subscapular artery, to enter the Latissimus dorsi on its 

 anterior (inner) surface. [635] 



Intercosto-humeral. This is the lateral cutaneous branch 

 of the second thoracic. It pierces the Intercostals and Serratus 

 magnus, crosses the axilla, piercing the deep fascia just beyond 

 the posterior axillary fold, and then descends on the arm to 



[164] 



