MUSCLES OF THE THORACIC LIMBS. 161 



68, f}. Inner surface with the scapula. Glenoid border with 

 the teres minor (Fig. 80, c], the teres major (Fig. 75, d), and 

 the long head of the triceps (Fig. 75, g). 



Action. Rotates the humerus outward. 



M. teres minor (Fig. 80, c). A small muscle from the 

 glenoid border of the scapula to the proximal end of the 

 humerus. 



Origin (Fig. 76, <?) by a sheet of tendinous fibres from the 

 glenoid border of the scapula beginning about one-fifth the 

 length of the border from the glenoid fossa and extending to 

 its middle. It is often attached to the infraspinatus (Fig. 

 So, b) and the caput longum of the triceps (Fig. 75, g}. 



Insertion (Fig. 83, d] by a short tendon into the tubercle 

 just distad of the infraspinatus fossa on the great tuberosity of 

 the humerus. 



Relations. Outer surface with the spinodeltoideus (Fig. 

 75, c\ acromiodeltoideus (Fig. 75, _/"), and the infraspinatus 

 (Fig. 80, ). Inner surface with the lateral (Fig. 75, Ji] and long 

 (Fig. 75, g] heads of the triceps and the capsule of the joint. 



Action. Assists the infraspinatus to rotate the humerus 

 outward. 

 B. MUSCLES ON THE MEDIAL SURFACE OF THE SHOULDER. 



(Fig. 77-) 



M. subscapularis (Fig. 77, a). A triangular mass from 

 the subscapular fossa to the lesser tuberosity of the humerus. 



Origin (Fig. 78, a). From the whole subscapular fossa 

 except along the fusiform area for the attachment of the levator 

 scapulae and the serratus anterior near the vertebral border, 

 and except over a quadrangular area about one centimeter long 

 near the glenoid angle. The origin is by fleshy fibres directly 

 from the periosteum except along two or three lines marked 

 by oblique ridges. To these lines are attached tendinous fibres. 

 At the glenoid border the area of origin sometimes occupies 

 part or the whole of the surface of the fossa for the origin of the 

 teres major, so that the teres arises from the fascia on the sur- 

 face of the subscapularis. At the coracoid border some of the 

 fibres may take origin from the adjacent fascia of the supra- 

 spinatus (Fig. 77, d}. 



