164 THE MUSCLES 



2 . Muscles of the Brachium or Upper Arm. 



M. clavobrachialis and the pectoralis group (Fig. 65, page 

 109) lie partly in this region; they have been described. 



M. coracobrachialis (Fig. 77, /; Fig. 79, c}. A very 

 short muscle covering the inner (medial) surface of the capsule 

 of the shoulder-joint. It extends from the coracoid process 

 to the proximal end of the humerus. 



Origin (Fig. 78, //). By a round tendon from the tip of 

 the coracoid process. 



Insertion (Fig. 82, e] usually by fleshy fibres on an area 

 five to eight millimeters long and about half as wide, which lies 

 on the medial side of the humerus parallel with the ridge which 

 runs from the dorsal end of the lesser tuberosity to the shaft 

 and close to it. The proximal end of the area is about one 

 centimeter from the proximal end of the head of the humerus. 



Relations. Medial surface with the biceps (Fig. 77, g), 

 pectoralis minor (Fig. 65, <?), and teres major (Fig. 77, ^). 

 Lateral surface with the capsule of the shoulder- joint. Dorsal 

 border with the subscapularis (Fig. 77, a) and the long portion 

 of the caput mediale of the triceps (Fig. 77, j). 



Action. Adducts the humerus. 



The part of the coracobrachialis just described is known as 

 the short head. A long head is sometimes found. It is a 

 conical bundle of fibres of varying size, which arises from the 

 tendon of origin of the short head. It passes distad into a long 

 and extremely slender tendon, the insertion of which varies 

 greatly in different individuals. It is commonly on the humerus 

 in the region of the supracondyloid foramen. 



M. epitrochlearis or extensor antibrachii longus (Fig. 

 65, r). A thin, flat muscle on the inner or medial side of the 

 brachium, from the lateral surface of the latissimus dorsi (Fig. 

 65, q] to the olecranon process of the ulna. 



Origin from the lateral or outer surface of the ventral border 

 of the latissimus dorsi (Fig. 65, q] near the insertion of the 

 cutaneus maximus. ' Fibres are often attached to the teres 

 major and the pectoralis minor. 



Insertion by a flat tendon which is closely connected with 



