138 ANATOMY OP UPPER EXTREMITY, ETC. 



the superior border near the commencement of its tendon ; 

 a small branch enters at the lower border, and a third, 

 accompanying the subscapular arteiy, is eventually dis- 

 tributed to the latissimus dorsi muscle. The subscapular 

 artery will also be noticed; passing along the lower border, 

 it gives a branch to the deep surface of this muscle, and 

 another to the dorsuru of the scapula, and anastomoses 

 with the posterior scapular branch of the subclavian at the 

 inferior angle of the bone. 



The TERES MAJOR MUSCLE lies below the sub-scapularis ; 

 it arises on the dorsum of the scapula from the flat surface 

 constituting its inferior angle, and, leaving a triangular 

 interspace between it and the lower border of the bone, is 

 inserted by a broad tendon, conjoined with that of the 

 latissimus dorsi, into the internal ridge of the bicipital 

 groove of the humerus. A synovial bursa exists between 

 the conjoined tendons. 



The SUPRA-SPINATUS MUSCLE is situated on the dorsum 

 of the scapula, above the spine of that bone; occupying the 

 whole of the supra-spinous fossa, from the walls of which 

 it arises ; it is inserted into the upper facet of the greater 

 tuberosity of the humerus, by a flattened tendon, which 

 forms part of the capsular ligament of th^ shoulder-joint. 

 Passing through the supra-scapular notch will be seen the 

 supra-scapular nerve, a branch of the brachial plexus, 

 which passes beneath this muscle to supply it, and then 

 curves round the external border of the spine, to be dis- 

 tributed to the infra-spinatus muscle. 



To trace this nerve, as well as to follow out the divided extremity 

 of the supra-scapular artery, the acromion process should be sawed 

 across at its base, and removed ; the muscle is thus wbolly displayed, 

 and is to be divided near its tendon, and dissected out from the fossa, 

 respecting all nervous and arterial branches which may be exposed. 



The supra-scapular artery is a branch of the subclavian 

 artery (p. 58), and passes over the ligament of the supra- 

 scapular notch, to penetrate beneath the supra-spinatns 

 muscle, which it supplies. A branch winds round the ante- 

 rior border of the spine of the scapula, to inosculate with 

 the dorsal branch of the subscapular, and with the branches 

 of the posterior scapular distributed on the dorsum of the 

 bone. 



The INFRA-SPINATUS MUSCLE occupies the infra-spinous 

 fossa, and is covered by a dense fascia, which, as well as 



