MUSCLES OF THE ANTERIOR EXTREMITY, 



83 



Fig- 73- 



(a) Porfio scapniaris, the 

 larger, external portion is 

 attached to the outer end of 

 the clavicle, and to the ante- 

 rior process of the precoracoid, 

 but it arises chiefly from the 

 dorsal surface of the scapula 

 (from the same ridge as the 

 m. suhscajmiaris), and lastly 

 from the anterior border and 

 ventral surface of the scapula. 

 The fibres pass outwards over 

 the shoulder-joint. 



(b) Pars clavicîiïaris (musc, 

 cle'ido-humeralïs, Klein) arises 

 from the inner extremity of 

 the clavicle and from the omo- 

 sternum and joins the portio 

 scajmlaris. 



The muscle is inserted into 

 the humerus, the under part 

 of the portio scapniaris being 

 attached to the upper portion 

 of the crista deltoidea ; the 

 outer fibres of this part, to- 

 gether with those of the pars 

 clavicular is, are attached to the extremity of the crista deltoidea and 

 to the inner surface of the humervis as far as the distal extremity; 

 just before its insertion the muscle is pierced by the tendon of the 

 m. sternoradialis. The deltoid draws the limb forwards. 



II. Muscles of the Fore-limb. 



A. 31uSCLES OF THE ARM. 



M. sternoradialis [biceps). See page 83. 

 56. M. triceps brachii (Fig. 73 t.r.). 



Dugès, scapulo-huméro-olecranien, n. 75. — Capes, Zen.ls.eT, m. aticonaeus. 

 This muscle lies on the upper or dorsal surface of the arm, and 

 has relations similar to those of the corresponding muscle in man. 

 The long head arises from the posterior border of the scapula at the 

 upper border of the glenoid cavity, and is here attached to the capsule 

 of the joint ; the inner head arises from the upper and iimer surfaces 



e 2 



Mwscle of x-ight shoulder and upper arm. The cora- 

 coids (co) and the clavicles (cl) have been drawn 

 asunder af ler cutting through the sternum. 



c.h. M. coraco-humeralis. 



cl Clavicle. 



- CO. Coi'acoid. 



d M. deltoideus. 



d' Clavicular portion of m. deltoïdes. 



i M. infraspinatus. 



i.s. M. interscapularis. 



l.a. M. evator anguli scapulae. 



l.d. M. latissimus dorsi. 



p' Sternal portion of m. deltoïdes. 



p" Anterior sternal portion of the m. pectoralis. 



p'" Posterior sternal portion of the m. pecUiralis. 



s Scapula. 



s.r. M. sternoradialis. 



t.r. M. triceps bracliii. 



