336 A MANUAL OF ANATOMY 



Insertion. — The inner side of the humerus at its centre for about 

 an inch and a half. Some of the upper fibres are inserted into a 

 fibrous band, which ascends in front of the tendons of the latissimus 

 dorsi and teres major to be attached to the humerus below the small 

 tuberosity. 



Nerve-supply. — ^The musculo-cutaneous nerve, by a branch which 

 derives its fibres from the seventh cervical. 



The muscle is directed downwards, outwards, and slightly back- 

 wards. 



Action. — ^To adduct and flex the humerus. It also braces the 

 head of the bone against the glenoid cavity. 



The muscle is pierced by the musculo-cutaneous nerve. 



Biceps Flexor Cubiti — Origin. — (i) The short head arises from the 

 tip of the coracoid process of the scapula in association with the 

 coraco-brachialis ; (2) the long head arises from the supraglenoid 

 tubercle of the scapula by a rounded tendon, which lies within the 

 capsular ligament of the shoulder- joint, and is continuous on either 

 side with the glenoid ligament. 



Insertion. — ^i) The posterior rough portion of the bicipital 

 tuberosity of the radius, being separated from the anterior smooth 

 portion by a bursa ; and (2) the deep fascia covering the muscles 

 arising from the internal epicondyle of the humerus by means of the 

 bicipital or semilunar fascia. 



The short head arises by a short tendon, and the tendon of the long 

 head is about 4 inches in length. This latter tendon arches over the 

 head of the humerus, and leaves the interior of the joint by entering 

 the bicipital groove, beneath the transverse humeral ligament. 

 Within the joint it is invested by a tubular sheath formed by the 

 synovial membrane, which accompanies it for a short distance in the 

 bicipital groove, and is then reflected upwards to become continuous 

 with the synovial lining of the capsular ligament. After leaving the 

 bicipital groove the tendon is replaced by a conical bundle of fleshy 

 fibres, and these join the fibres derived from the short head about the 

 centre of the arm, giving rise to an elongated, oval, fleshy belly. 

 At the level of the epicondyles of the humerus the belly gives 

 place to the strong tendon of insertion, which sinks into the anti- 

 cubital space, and undergoes a quarter of a turn before reaching its 

 insertion. From the inner side of the tendon, towards its upper part, 

 a strong band of fibres is given off, which passes to the deep fascia 

 covering the muscles arising from the internal epicondyle. It is 

 called the bicipital or semilunar fascia, and it passes over the brachial 

 artery, whilst the median basilic vein lies upon it. 



Nerve-supply. — The musculo-cutaneous nerve, which is a branch 

 of the outer cord of the brachial plexus, its fibres being derived from 

 the fifth, sixth, and seventh cervical. 



Action. — (i) To flex the elbow-joint ; (2) to supinate the forearm ; 

 (3) by its short head to adduct and flex the arm, and (4) by its long 

 head to raise the arm at the shoulder. 



Internal to the muscle in the upper half is the coraco-brachialfe. 



