MUSCLES OF THE SHOULDER AND ARM. 35 



MUSCLES OF THE ARM. 



i6. The Biceps Muscle lies on the inner and ven- 

 tral face of the humerus. Its anterior end is covered 

 over by the insertion of the pectoralis muscles upon 

 the humerus. The biceps arises by a single strong 

 tendon from the edge of the glenoid fossa (coracoid 

 process), the tendon passing through the capsular liga- 

 ment of the joint. The muscle is inserted by a strono- 

 tendon chiefly into the ulna, though it is attached also 

 to the radius by a smaller slip, 



17. The Coraco-brachialis is a small muscle lying 

 to the inner side of the proximal end of the biceps. 

 It arises by a single tendon from the coracoid 

 process, passes over the head of the humerus, and is 

 inserted into the inner side of the humerus just 

 beneath the tendon of the teres major. 



18. The Triceps Brachialis is the large mass of 

 muscle lying along the dorsal aspect of the humerus. 

 It serves to extend the forearm. In the dog it has 

 four divisions. 



a. The largest division is an irregular muscle, 

 formed apparently by the fusion of two muscles ; it 

 arises along the posterior margin of the scapula, the 

 attachment being especially strong near the glenoid 

 fossa, and is inserted into the olecranon process of the 

 ulna. The other three divisions lie between this one 

 and the humerus, and agree pretty well in position 

 with the three heads of the triceps in man. 



b. The most internal of these three divisions arises 

 from the humerus at the insertion of the coraco- 

 brachialis, and also by a line of fascia along the middle 

 third of the humerus. 



