736 THE ANATOMY OF THE Rl'FFED GROUSE 



crest of the humerus. Its function is movement of the skin. 



M. supracoracoideus is the great elevator of the winp. The muscle lies under the M. pec- 

 toralis thoracicus and originates from the sternum, memlirana coraco-clavicularis. and the 

 coracoid. and its tendon passes through the foramen Iriosseum to insert on the lateral tubercle 

 of the humerus. 



M. coracobrachialis anterior is a small muscle stretching between the tip of the coracoid 

 and the ventral surface of the proximal head of the humerus. It lies under the tendon of M. 

 supracoracoideus. 



M. coracobrachialis posterior lies under the dorsal part of M. pectoralis superficialis. It 

 originates along the coracoid and the anterior lateral process of the sternum and inserts by a 

 tendon on the ventro-external border of the humerus. 



M. biceps is the strong flexor of the ulna on the humerus. It originates from the strong 

 fascia covering the head of the humerus and the head of the coracoid and extends along the 

 ventro-lateral border of the humerus to insert on the ulna a short distance distal of the head. 

 A slip, M. biceps propatagialis, extends to the propatagium. 



M. brachialis is a small muscle which connects the proximal portion of the ulna with the 

 distal head of the humerus. It lies medial to the insertion of M. biceps. 



M. latissimus dorsi is divided into two parts. Pars anterior originates from the neural 

 ridge of the first thoracic vertebra and passes over M. rhomboideus superficialis to insert on 

 the medial border of the humerus. It passes ventral to M. deltoideus and M. triceps. The 

 pars posterior originates from the spines of the sacral and thoracic vertebrae and joins the 

 pars anterior where it jiasses to the humerus. 



M. deltoideus propatagialis arises from the dorsal and anterior tip of the clavicle and passes 

 to the fascia covering the muscles of the ulna and radius. It soon forms its tendon, which is 

 wide, and merges with that of M. biceps propatagialis. This tendon divides into a longus 

 portion which extends to the distal area of the ulna and a brevis portion which attaches more 

 liasallv. 



M. deltoideus longus originates from the ti|) of the ( ]a\ ide and the adjoining area of the 

 scapula. It passes posteriorly to insert on the proximal half of the medinl surface of the 

 humerus. It is entirely fleshy. 



M. deltoideus brevis is a small muscle which connects the tip of the clavicle to the anterior 

 face of the humerus. It lies dorsal to the tendon of M. supracoracoideus. 



M. dorsalis scapulae is the large muscle which originates along the lateral border of the 

 entire ])ost-glenoid region of the scapula and whose fibers converge to form a strong tendon. 

 This tendon inserts on the proximal end of the humerus at llie |)recessus medialis humeri. 



M. proscapulohumeralis is small and partly covered by the jireceding muscle. It originates 

 on the anterior portion of the lateral liorder of the scapula and inserts on the Ininieriis at the 

 origin of M. triceps. 



M. subcoracoideus arises in three parts wiiieh join lo insert on the medial liead of tlie 

 humerus. Caput coraeoideum is a large, division originating on the internal surface of the 

 coracoid. Caput scapulare internum arises on the internal face of the seapiila and the ( a|>iil 

 seapulare externum arises on tiie external fare. This last head is small. 



M. triceps is the great extensor of the ulna and radius. It is divided into three heads. Caput 



