234 ANTERIOR HUMERAL REGION. 



By its internal border with the axillary and brachial vessels and nerves, 

 particularly with the median and external cutaneous nerve, by the 

 latter of which it is pierced. By the external border with the short 

 head of the biceps and brachialis anticus. 



The BICEPS (bis xtfaXeu two heads) arises by two tendons, one 

 the short head, from the coracoid process in common with the coracp- 

 brachialis ; the other the long head, from the upper part of the glenoid 

 cavity. The muscle is inserted by a rounded tendon, into the tuber- 

 cle 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 tubero- 

 sities of the humerus, the bicipital groove. A small synovial bursa 

 is interposed between the tendon of insertion, and the tubercle of the 

 radius. At 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 re- 

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

 alis anticus ; from the latter 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 deltoid 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 insertion of 

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

 intermuscular septa attached to the condyloid ridges. Its fibres con- 

 verge to be inserted into the coronoid 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, anterior ligament of the elbow- 

 joint, and intermuscular aponeurosis. The latter separates it from the 

 triceps. By its external border with the supinator longus, extensor 

 carpi radialis longior, musculo-spiral 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. 



