208 POSTERIOR HUMERAL REGION. 



by two tendons, one the short head, from the coracoid process in 

 common with the coraco-brachialis ; the other the long head, from 

 the upper part of the glenoid cavity. The muscle is inserted by a 

 rounded tendon, into the tubercle of the radius. The long head, a 

 long slender tendon, passes through the capsular ligament of the 

 shoulder joint enclosed in a sheath of the synovial membrane ; after 

 leaving the cavity of the joint, it is lodged in the deep groove that 

 separates the two tuberosities of the humerus, the bicipital groove. 

 A small synovial bursa is interposed between' the tendon of inser- 

 tion, and the tubercle of the radius. M the bend of the elbow, the 

 tendon of the biceps gives off from its inner side a broad tendinous 

 band, which protects the brachial artery, and is continuous with the 

 fascia of the fore-arm. 



Relations. By its anterior surface with the deltoid, pectoralis 

 major, superficial and deep fascia and integument. By its posterior 

 surface the short head rests upon the subscapularis, from which it is 

 separated by a bursa. In the rest of its extent the muscle is in rela- 

 tion with the humerus, the teres major, latissimus dorsi, and brachi- 

 alis anticus, from which it is separated by the external cutaneous 

 nerve. By its inner border with the coraco-brachialis, brachial 

 artery and veins, and median nerve ; the brachial vessels crossing its 

 tendon at the bend of the elbow. By its outer border with the del- 

 toid and supinator longus. 



The Brachialis anticus is a broad muscle covering the whole of 

 the anterior surface of the lower part of the humerus ; it arises by 

 two fleshy serrations from the depressions on either side of the inser- 

 tion of the deltoid, and from the anterior surface of the humerus. 

 Its fibres converge to be inserted into the coracoid process of the 

 ulna. 



Relations. By its anterior surface with the biceps, external cuta- 

 neous nerve, brachial artery and veins, and median nerve. By its 

 posterior surface with the humerus, and anterior ligament of the 

 elbow joint. By its external border with the supinator longus, exten- 

 sor carpi radialis longior, musculo-spinal nerve, and recurrent radial 

 artery. By its internal border with the intermuscular aponeurosis, 

 which separates it from the triceps and ulnar nerve, and with the 

 pronator radii teres. 



Actions. The coraco-brachialis draws the humerus inwards, and 

 assists in flexing it upon the scapula. The biceps and brachialis 

 anticus are flexors of the fore-arm, and the former a supinator. The 

 brachialis anticus is a powerful protection to the elbow-joint. 



Posterior Humeral region. 

 Triceps extensor cubiti. 



Dissection. Remove the integument and fascia from the posterior 

 aspect of the upper arm. 

 The Triceps (r^Ts xs<po.Xou, three heads,) arises by three heads. 



