80 THE MUSCLES. 



General arrangement of the muscles of the shoulder-blade. 



The muscles attached to the scapula and suprascapula are : 



I. Muscles of the back [m. cucuUaris and m. retrahenH scap.). 

 1. Muscles of the neck {in. omohjoideus). 



3. Muscles of the abdomen [portio scapvlarh of the m. oblicpms 

 externus). 



4. True shoulder muscles [in. levator angvli scapvlac, m. sternoclei- 

 rlomastoirhus ; in.protrahens scapulae ; mm. transverso-êcapularis major, 

 minor, and terf'nis s. serratus ; in. 'inter-'icapnlarls ; m. suhscapidaris ; 

 and the long head of the m. tricep)s). 



Prom above the following" are visible : in. cncullaris, a portion of 

 the in. subscajjvlaris, and the transfer so-scajyularis inaior. 



From below (after cutting through and drawing aside the two 

 halves of the sternum) may be seen : the omohjoideus, sternocleido- 

 mastoideus, levator anynli scapulae, protraliens scapulae, transverso- 

 scapnlaris minor and tertius, inferscajyularis and snhscapularis. 



B. Ventral Muscles of the Shoulder (Pectoral 

 Muscles) 



These arise from the sternum or shoulder-girdle and are inserted 

 either into the humerus or into the radio-ulnar. 



52. M. pectoraJis (Fig. 73). 

 This is placed on the ventral surface of the shoulder-girdle and 

 consists of the following parts : 



(a) Vort'w stenialis anterior (Ecker), (Figs. 72, 73 i/). 



Dugès, clavi-huniéral, n. 70 (port, clavic. du grand pectoral). 



This is the anterior portion of the in. pectoralis, it arises from the 

 sternum proper and the epicoracoids. Broad at the origin, it be- 

 comes narrower as it runs outwai-ds into a tendon attached to the 



crista deltoid ea humeri. 



{p) Portio stenialis posterior (Ecker), (Figs. 72, 737/'). 



Dugès, sterno-huméral, n. 71 (port, sternal du grand pectoral). — Klein, 

 humero-sternalh. 



This miTscle is placed immediately behind the portio stenialis 

 anterior, it has a somewhat broad origin from the sternum and 

 xiphisternum ; the muscle runs outwards and slightly forwards to 

 be inserted into the groove beside the crista deltoidea humeri. The 

 tendon of the m. sterna-radial is passes between these two portions 

 of the m,. pectoralis. 



