86 THE SUPERIOR EXTREMITY 



which lies along the lower border of the infraspinatus. It 

 arises from an elongated flat impression on the dorsal aspect of 

 the axillary border of the scapula, and from the fascial septa 

 which intervene between it and the two muscles between 

 which it lies, viz. the infraspinatus and teres major. It is 

 inserted into the lowest of the three impressions on the 

 greater tubercle of the humerus, and also, by fleshy fibres, 

 into the body of the bone for about 12.5 mm. (half an inch) 

 distal to the tubercle (Fig. 48, p. 113). As it approaches its 

 insertion it is separated from the teres major by the long 

 head of the triceps brachii. The teres minor is supplied by 

 a branch from the axillary nerve. It is an adductor and 

 lateral rotator of the arm. 



M. Teres Major. The part which the teres major plays in 

 the formation of the quadrilateral and triangular spaces has 

 already been seen. It arises from the oval surface on the 

 dorsum of the scapula close to the inferior angle of the bone 

 (Fig. 38, p. 83), and also from the septum which the infra- 

 spinous fascia sends in to separate it from the infraspinatus 

 and teres minor muscles. It is inserted into the medial 

 lip of the intertubercular sulcus on the proximal part of the 

 humerus (Fig. 45, p. 107). It is supplied by the lower 

 subscapular nerve, and it is an adductor, a medial rotator 

 and an extensor of the arm. 



M. Subscapularis. The subscapularis muscle arises from 

 the whole of the subscapular fossa, with the exception of 

 a small portion near the neck of the scapula ; it takes 

 origin also from the groove which is present on the costal 

 aspect of the axillary border of the bone (Fig. 24, p. 46). 

 Its origin is strengthened by tendinous intersections, which 

 are attached to the ridges on the costal surface of the 

 scapula. The fleshy fibres thus derived converge upon a 

 stout tendon, which is inserted into the lesser tubercle of 

 the humerus ; a few of the lower fibres, however, gain 

 independent insertion into the body of the humerus distal 

 to the tubercle (Fig. 45). 



As the muscle proceeds laterally to its insertion, it passes 

 under an arch formed by the coracoid process and the con- 

 joined origin of the short head of the biceps brachii and the 

 coraco-brachialis. The subscapularis is supplied by the upper 

 and lower subscapular nerves. It is an adductor and medial 

 rotator of the arm. 



