MUSCLES OF THE THORACIC LIMBS. 165 



that of the pectoantibrachialis (Fig. 65, m) 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, q), and the cutaneus maximus. Inner 

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

 (Fig. 65, s], and caput mediale (Fig. 77,7', k] of the triceps. 



Action. Extends the antibrachium and tends to supinate 

 the hand by rotating the ulna. 



M. biceps brachii (Fig. 77, g\ Fig. 65, /). A thick, fusi- 

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



Origin (Fig. 76, 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, U] on the bicipital 

 tuberosity of the radius (Fig. 86, k]. 



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, k} 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. 77, /"), the teres major, (Fig. 

 77, c), the intermediate portion of the caput mediale of the 

 triceps (Fig. 77, k}, and the short portion (Fig. 77, /) of the 

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

 65, o] and the brachialis (Fig. 79, i}. 



Action. Flexes the forearm, and tends to supinate the 

 hand. 



