484 



THE ARTERIES OF THE UPPER LIMB. 



5. The subscapular artery (iv), the largest branch of the axillary artery, 

 arises near the lower border of the subscapularis muscle, along which it proceeds 

 downwards and backwards, towards the inferior angle of the scapula, accompanied 

 by the long subscapular nerve. It soon becomes considerably diminished in size, 

 owing to its giving off a large branch to the dorsum of the scapula, and it terminates 

 in branches to the subscapularis, serratus magnus, teres major and latissimus dorsi 

 muscles. Its final ramifications anastomose with the long thoracic, the intercostal, 

 and the posterior scapular arteries. 



The dorsal branch leaves the subscapular artery about an inch from its origin, 

 and is commonly larger than the continuation of the vessel. Directed backwards 

 through the triangular interval bounded above by the subscapularis, below by the 

 teres major, and externally by the long head of the triceps muscle, and turning 

 closely round the border of the scapula, which is commonly grooved to receive it, it 



Fig. 356. ANASTOMOSES OP THE 



ARTERIES ON THE VENTRAL SUR- 

 FACE OF THE SCAPULA, &C. 



(R. Quain.) 



a, coracoid process ; b, tendon of 

 long head of biceps ; c, capsular liga- 

 ment of shoulder-joint ; d, tendon of 

 latissimus dorsi ; e, teres major ; A, 

 axillary, and A', brachial artery ; 

 1, suprascapular artery, giving off 

 1', its subscapular branch, as it 

 passes over the suprascapular liga- 

 ment ; 2, 2, posterior scapular artery ; 

 2', 2', its ventral branches; 3, 3, stem 

 of the subscapular artery at its origin 

 from the axillary, continued into the 

 dorsal scapular artery, which is turn- 

 ing to the back of the scapula, and 

 gives off 3', its ventral branch, pro- 

 ceeding to anastomose with the ven- 

 tral branches of the suprascapular 

 and posterior scapular arteries ; 4, 



thoracic division of the subscapular artery ; 5, anterior circumflex artery ; 6, posterior circumflex, in 

 this case arising above the subscapular, and passing back through the quadrilateral intermuscular space. 



passes between the teres minor and the bone and ramifies in the infraspinous fossa, 

 where it anastomoses with the suprascapular and posterior scapular arteries 

 (fig. 353). 



The dorsal scapular artery gives off, as it passes through the triangular space, 

 one or two slender ventral branches (fig. So 6, 3'), which ramify in the subscapular 

 fossa beneath the subscapularis muscle, and anastomose with twigs from the supra- 

 scapular and posterior scapular arteries ; and a considerable descending branch (fig. 

 353, 4') which runs in the groove between the origins of the teres minor and major, 

 supplying both muscles, to the lower angle of the scapula. Small offsets are also 

 furnished to the long head of the triceps and the hinder part of the deltoid muscle. 



6. The posterior circumflex artery, a considerable vessel but smaller than 

 the subscapular, immediately below which it arises, is directed backwards in 

 company with the circumflex nerve, passing through the quadrilateral space between 

 the teres muscles, the humerus, and the long head of the triceps, and therefore 

 separated by the last from the dorsal scapular artery. It winds round the humerus, 

 and terminates by ramifying in the deltoid muscle, giving branches also to the 

 shoulder-joint, to the teres muscles, to the long and outer heads of the triceps, and 

 to the skin, and anastomosing with the anterior circumflex and acromio-thoracic 

 arteries, as well as with the superior profunda branch of the brachial. 



