INTERNAL SCAPULAR GROUP. 215 



tendinous slips from the posterior fossa, and a small tubercle on 

 the external side of the rim of the glenoid cavity. 



Insertion. To the deltoid ridge. 



Relation. Externally with the teres externus and postea- 

 spinatus : internally with the caput magnum, caput medium, and 

 capsular ligament. 



Action. Like the last, to abduct, and rotate the humerus 

 outwards. 



INTERNAL SCAPULAR GROUP. 



Subscapularis. 

 Teres interims. 

 Scapulo-humeralis posticus. 



SUBSCAPULARIS. 



(Subscapulo- troch in eus. ) 



(Fie. 79. a.) 



Situated on the inner side of the shoulder blade, occupying 

 the subscapular fossa, it is fan-shaped, forming three points 

 superiorly, its fibres converging downwards. It is covered by 

 strong fascia, from which arises the subscapulo-hyoideus. 



Origin. From the whole of the subscapular fossa. 



Insertion. To the internal humeral trochanter, by a strong ten- 

 don passing over its summit, where there is a small synovial bursa. 



Relation. Externally with the scapula ; internally with the 

 serratus magnus ; anteriorly with the antea-spinatus, with which 

 it blends, the two forming a space through which passes the pre- 

 scapular artery ; posteriorly with the teres internus. 



Action. To adduct the arm, and perhaps to rotate it slightly 

 inwards. 



TERES INTERNUS. 



(Teres Major Subscap u lo-h u mera Us.) 

 (FiG. 79. 6.) 



This, an adductor of the arm, is situated just behind the sub- 

 scapularis, at the posterior border of the scapula ; it runs obliqely 

 downwards, corresponding to the teres externus. It is elongated, 

 wide in the middle, tapering at the extremities, its posterior edge 

 being thin. 



Origin. From the dorsal angle and posterior costa of the 

 scapula. 



