INTERNAL SCAPULAR REGION 445 



ANTERO-INFERIOR SCAPULAR REGION 



CoRACO HUMERALis is Situated on the infero-internal part of the 

 shoulder. Origin — from a tubercle on the inner side of the coracoid 

 process of the scapula. Insertion — bifid : one portion on a tubercle on 

 the middle third of the antero-internal part of the body of the humerus ; 

 the other passes over the insertions of the teres internus and latissimus 

 dorsi, just below which points it is inserted. Action — to extend the 

 humerus and draw it inwards. 



Flexor brachii is placed upon the antero-inferior part of the shoulder. 

 Origin — from the antero-inferior part of the coracoid process of the scapula, 

 passing over the trochlea formed by the tubercles of the humerus. Inser- 

 tion — to the supero-anterior and inner part of the body of the radius. 

 Action — to extend the radius, and at the same time to elevate it. 



THE INTERNAL SCAPULAR REGION 



SuBSCAPULARis fiUs up the venter scapul b. Origin — from the two inferior 

 thirds of the ventral surface, extending from the anterior to the posterior 

 border of the scapula. Insertion — to the inner ridge just below the lesser 

 tubercle of the humerus. Action — to draw the humerus inwards and 

 upwards. 



Teres internus vel major is situated upon the posterior part of the 

 shoulder. Origin — from the inner surface of the supero-posterior angle 

 and from a slight indentation internally placed to the posterior border of 

 the scapula. Insertion — to the rough tubercle on the inner side of the 

 body of the humerus, in company with the latissimus dorsi. Action — to 

 draw the humerus inwards. 



ScAPULO ulnaris lies upon the posterior part of the shoulder. Origin — 

 from the supero-posterior and inner part of the scapula, extending from 

 its angle to just above its glenoid cavity. Insertion — to the olecranon and 

 to the postero-internal part of the ulna, extending from its summit to where 

 the ulna joins the radius. Action — to assist the caput magnum of the 

 triceps. 



ScAPULO HUMERALIS POSTICUS is situated upon the posterior part of the 

 shoulder. Origin — bifid ; one part from the superior two-thirds of the 

 inner surface of the posterior border of the scapula, the other from above 

 the postero-internal surface of the glenoid cavity. Insertion — to the 

 supero-posterior part of the humerus. Action — it serves as a ligament, 

 protecting the joint. 



Triceps extensor brachii (caput parvum) is situated on the infero- 

 internal part of the shoulder. Origin — from the internal and middle third 

 of the humerus. Insertion — to the olecranon and to a tubercle on the 

 supero-internal part of the ulna, close to the olecranon. Action — to extend 

 the arm. 



