300 SHOULDER-GIRDLE IN MONOTREMES, 



Ornithorhynchus. 



Origin. M. coraco-hrachialis longus. (Figs. 7, 9, Cb. L.). — 

 This muscle arises by a tendon in common with the coracoid head 

 of the biceps from the external portion of the distal extremity of 

 the coracoid. 



Insertion. Running outwards a thin belly of muscle 

 develops, and after passing superficial to the tendons of the two 

 parts of the latissimus dorsi, the muscle is inserted by a narrow 

 tendon, on a ridge running from the internal condyle towards the 

 distal extremity of the pectoro-deltoid ridge, and lying between 

 the antero-internal and antero-external faces of the humerus ; being 

 placed distal to the anterior part of the latissimus dorsi. 



Relations. The muscle at its origin is superficial to the 

 coraco-brachialis brevis, but on account of its narrowness it does 

 not hide from view the brevis, as in Echidna. 



O r i <^ i n. (6) M. coraco-hrachialis hre.vis. (Figs. 7, 9, Cb. B.). — 

 This muscle arises from the concave outer border of the coracoid 

 lying between the glenoid cavity and the origin of the coraco- 

 brachialis longus from the distal extremity of the coracoid, and 

 also from the ventnd face of the bone immediately adjoining this 

 concave border. 



Insertion. Running outwards, the muscle is inserted on 

 the antei'O-lateral face of the humerus on a ridge which runs from 

 the greater to the lesser tuberosity, being placed immediately 

 distal to the edge of the deep depression between the two tuber- 

 osities. Its insertion is bounded internally by the epicoraco- 

 brachialis and teres major ; externally and distally by the posterior 

 part of the latissimus dorsi ; while the epicoraco-humeral is placed 

 external at the proximal end of the humerus. 



Relations. At its origin the fibres of this muscle are 

 intimately connected with the fibres of the epicoraco-brachialis ; it 

 likewise comes into relation with the insertion of the costo-cora- 

 coideus on the dorsal part of the distal extremity of the coracoid. 

 Both parts of the biceps and the coraco-brachialis longus lie 

 superficial to and partly hide it from view. 



