MUSCLES OF THE THOR/iaC LIMBS. 165 



that of the pectoantibrachialis (Fig. 65, ;;/) and is continuous 

 with the general antibrachial fascia, into the caudal border of 

 the cutaneous (dorsal) surface of the olecranon process of the 

 ulna. 



Relations. — Outer (medial) surface with the integument, the 

 latissimus dorsi (Fig. 65, </), and the cutaneus maximus. Inner 

 (lateral) surface with the biceps (Fig. 65, /), caput longum 

 (Fig. 65, s), and caput mediale (Fig. yj.j, k) of the triceps. 



Action. — Extends the antibrachium and tends to supinate 

 the hand by rotating the ulna. 



M. biceps brachii (Fig. yy, g; Fig. 65, /). — A thick, fusi- 

 form muscle lying on the front (ventral) surface of the humerus. 



Origin (Fig. y6, c) by a strong, round tendon from the 

 bicipital tubercle of the glenoid angle of the scapula, at its 

 coracoid margin. (In man there is a second head — coracoid 

 head — from the coracoid process.) The tendon passes through 

 the capsule of the joint and then along the bicipital groove, 

 which is converted into a canal by a strong ligament. 



Insertion by a rounded tendon (Fig. 87, I)) on the bicipital 

 tuberosity of the radius (Fig. 86, /'). 



Relations. — The tendon of origin passes through the capsule 

 of the joint, which is covered by a part of the pectoralis minor. 

 The muscle is then spanned for the middle part of its course 

 by the bicipital arch (Fig. 65, /'), a description of which is 

 given below. Farther distad it is covered by the clavobrachial 

 (Fig. 65, /■) and epitrochlearis (Fig. 65, r). At its distal end 

 (Fig. 79, /') the muscle passes between the pronator teres on 

 the radial side and the conjoined tendon of the brachialis and 

 clavobrachial (Fig. 79, /') on the other. The biceps lies 

 throughout most of its length on the ventral surface of the 

 humerus, and touches along the medial border of its inner sur- 

 face the coracobrachialis (Fig. yy , f), the teres major (Fig. 

 yy, e), the intermediate portion of the caput mediale of the 

 triceps (Fig. yy, /')» '^'^'^ ^^^^ short portion (Fig. yy, I) of the 

 same. Its lateral border touches the pectoralis minor (Fig. 

 65, 0) and the brachialis (Fig. 79, ?'). 



Action. — Flexes the forearm, and tends to supinate the 

 hand. 



