COR ACO-BRACHI ALIS. BICE PS. 219 



head of the biceps, with which latter it is for some distance conjoined in a common 

 tendon. The lower end of the muscle is inserted into the inner border of the 

 humerus near its middle, on a linear impression of from one to two inches in length, 

 between the origins of the triceps and the brachialis anticus. Higher up, some of 

 its fibres are frequently inserted into a fibrous band which is prolonged upwards, 

 forming an arch over the latissimus dorsi and teres major tendons, to be attached to 

 the humerus close below the small tuberosity. 



Relations. This muscle is usually pierced by the musculo-cutaneous nerve ; its outer 

 border is overlapped by the biceps muscle, and its inner is in contact with the brachial artery, 

 by which it is crossed obliquely near its insertion. It lies in front of the tendons of the 

 subscapularis, latissimus dorsi, and teres major, and is covered in great part by the deltoid and 

 pectoralis major muscles. 



Varieties. This muscle is subject to considerable varieties, which seem to indicate, 

 according to Wood, that it consists typically of three parts, viz., 1, a superior short one arising 

 from the coracoid process, or near it, and running over the subscapularis muscle, to be 

 inserted close below the small tuberosity of the humerus ; 2, a middle part corresponding 

 most nearly to that usually described in human anatomy, of intermediate size, and placed 

 between the first and third ; 3, an inferior part, which is the longest and most superficially 

 placed, and descends to the inner condyle, or near it, and in many instances is inserted into a 

 supracondylar process. The middle division of the muscle is most constant in man, but is 

 generally accompanied by a part of the third, the musculo-cutaneous nerve passing between 

 them. The first and third constitute the most marked varieties in man, and all three are 

 found in various forms and degrees of development in different animals. The innermost 

 fibres of the muscle are sometimes inserted into the internal intermuscular septum, or the 

 internal brachial ligament ; and a fasciculus has been observed joining the inner head of the 

 triceps. (Wood, Journ. Anat., i. 45.) 



The biceps flexor cubiti muscle has two heads of origin : one of these, the 

 internal or short head, arises conjointly with the coraco-brachialis from the coracoid 

 process of the scapula by a tendon which is soon continued into muscle ; the other, 

 the long head, arises from the scapula at the upper end of the glenoid cavity, within 

 the capsule of the shoulder-joint, by a rounded tendon which is continuous on each 

 side with the glenoid ligament ; and this tendon, passing over the head of the 

 humerus, leaves the joint by the bicipital groove, gradually enlarging into the 

 fleshy head as it descends. The two muscular heads meet, and becoming closely 

 applied together, form an elongated and thick belly, occupying the middle and lower 

 parts of the arm : a little above the bend of the elbow, the muscle suddenly becomes 

 narrower, and is continued into the thick tendon of insertion. This tendon, slightly 

 twisted upon itself as it descends, is inserted into the rough posterior portion of the 

 tuberosity of the radius, being separated from the anterior smooth surface of that 

 process by a synovial bursa. There is often a second bursa on the inner side of the 

 tendon, between it and the bicipital hollow of the ulna. From the inner side of the 

 tendon and lower part of the muscle a strong flat aponeurotic band, called the semi- 

 lunar fascia, passes downwards and inwards, and becomes blended with the deep 

 fascia of the forearm over the muscles arising from the internal condyle. 



Relations. Concealed above by the deltoid and pectoralis major muscles, the fleshy belly 

 of the biceps forms in the rest of its extent the prominence of the front of the arm. It lies 

 in its upper part on the humerus. and in its lower on the brachialis anticus ; by its inner 

 margin it is in contact in its upper half with the coraco-brachialis, and in its lower with the 

 brachial artery. Its inferior tendon passes backwards between the supinator longus and 

 pronator teres muscles, and the semilunar fascia is stretched across the brachial vessels and 

 median nerve. 



Varieties. The biceps is one of the most variable muscles in the body. The commonest 

 variety is the occurrence of a third head (10 per cent.), which arises from the humerus in 

 more or less close connection with the brachialis anticus and the insertion of the coraco- 

 brachialis, and is inserted into the coracoid portion of the muscle and the semilunar fascia : 

 this head lies generally on the outer side of the brachial artery, but has sometimes been found 

 covering the vessels. Less frequently an additional head springs from the outer side of the 



