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 internus. 

 Scapulo-humeralis posticus. 



SUBSCAPULARIS. 



{Suhscapulo-trochineus. ) 



(Fig. 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 — Suhscapulo-humeralis.) 

 (Fig. 79. h.) 

 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. 



