380 



THE MUSCULAR SYSTEM. 



Infraspinatus 

 (insertion) 



Nerve-Supply. The nerve to the coracobrachialis comes from the 7th or 6th and 7th 

 cervical nerves. Incorporated with the musculo-cutaneous, the nerve separates to supply the 

 muscle before the latter nerve pierces it. 



Action. The muscle assists the biceps to raise the arm and draw it medially. 



M. Biceps Brachii. The biceps brachii arises by two tendinous heads. (1) 

 The short head (caput breve) is attached in common with the coracobrachialis to 



the tip of the cora- 

 coid process of the 

 scapula (Fig. 333, 

 p. 372). Concealed 

 by the deltoid and 

 tendinous at first, 

 this head forms a 

 separate fleshy 

 belly, which is 

 united to the long 

 hea d by an invest- 

 ment of the deep 

 fascia. (2) The 

 long head (caput 

 longum) arises by 

 a round tendon 

 from the supra- 

 glenoidal tuberos- 

 ity at the root of 

 the coracoid pro- 

 cess and from the 



Supraspinatus 

 (insertion) 



.Subscapularis 

 (insertion) 



Pectoralis major 

 (insertion) 



Latissimus dorsi 

 (insertion) 



Teres major 

 "(insertion) 



Deltoid (insertion) 



Brachioradialis 

 "(origin) 



Extensor carpi 

 -radialis longus 

 k (origin) 



Common tendon 

 for origin of 

 pronator teres 

 and flexor 

 muscles of 

 forearm 



Common tendon for origin of 

 extensor muscles of forearm 



FIG. 340. MUSCLE - ATTACHMENTS TO 

 THE ANTERIOR ASPECT OF THE 

 EIGHT HUMERUS. 



: lateral h 



Triceps : medial 

 head (origin) 



Coracobrachialis 

 (insertion) 



labrum glenoidale 

 on each side. 

 Its tendon passes 

 through the cavity 

 of the shoulder - 

 joint, and, emerg- 

 ing from the cap- 

 sule beneath the 

 transverse humeral 

 ligament (invested 

 by a prolongation 

 of the synovial 

 membrane), it 

 occupies the inter- 

 tubercular groove 

 of the humerus 



by a fascial pro- 

 longation of the 

 tendon of the pec- 



FIG. 341. MUSCLE - ATTACHMENTS TO toralis major. In 

 THE POSTERIOR SURFACE OF THE fche arm it formg 

 EIGHT HUMERUS. 



fleshy belly united 



to that derived from the short head by an envelope of deep fascia. 



The insertion of the muscle is likewise twofold. (1) The two bellies become 

 connected to a strong tendon, attached deeply in the hollow of the elbow 

 to the rough dorsal portion of the tubercle of the radius (Figs. 335, p. 375, 

 and 348, p. 389). A bursa separates the tendon from the volar portion of the 

 tuberosity. (2) From the medial and anterior part of the tendon, and partly 

 in continuity with the fleshy fibres of the muscle, a strong membranous "band 

 (the lacertus fibrosus) extends, distally and medially, over the hollow of the elbow 

 to join the deep fascia covering the origins of the flexor and pronator muscles 



Common tendon 

 for origin of 

 xtensormuscles 

 of forearm 

 Anconseus 

 (origin) 



