13 



axillaris at the posterior border of the M. subscapularis. Before exposing 

 the A. subscapularis first trace the branch, A. thoracico-dorsalis, that arises 

 from the subscapularis i to 2 cm. from its origin (PL I, immediately below 

 22). This artery extends obliquely across the inner face of the teres major 

 supplies small branches to it and to the axillary lymph gland and terminates 

 in the latissimus and panniculus. Transect the M. teres major near the 

 middle and turn it aside. Now trace the A. subscapularis between the 

 Mm. subscapularis and teres major across the inner surface of the caput 

 longum tricepitis to the posterior angle of the scapula. The A. subscap- 

 ularis gives off the following branches: 



(i) A. thoracico-dorsalis already dissected. See above. 



(2) A. circumflexa humeri posterior arises i to 2 cm. peripheral to 

 the A. thoracico-dorsalis. It accompanies the N. axillaris to the deep face 

 of the M. deltoideus and is distributed to this muscle and also to the caput 

 longum, the caput laterale, the brachialis, the teres minor and a small twig 

 to the capsule of the scapulo-humeral joint. 



(3) A. circumflexa scapulae arises from the subscapularis 5 to 8 cm. 

 peripheral to the A. circumflexa humeri posterior and extends directly to 

 the posterior border of the scapula; here it divides into two branches of 

 which one passes to the outer and the other to the inner surface of the 

 scapula. The outer branch crosses, at nearly a right angle, the outer face 

 of the scapula, a little below the spine, and is distributed to the infra and 

 supraspinati and the teres minor. The inner branch is distributed to the 

 subscapularis. The general course of these vessels is indicated by the 

 vasctolar grooves of the scapula. (See cleaned scapula.) 



(4) Rami musculares. Numerous small branches of the A. sub- 

 scaptilaris are supplied to the Mm. subscapularis and teres major. Two 

 or more large branches of the A. subscapularis are given off to the caput 

 longum, the tensor fasciae antebrachii, the infraspinatus and the deltoideus. 

 The V. subscapularis accompanies the artery. 



A. circumflexa humeri anterior arises from the brachialis i to 4 cm. periph- 

 eral to the subscapularis. It passes between the humerus and the M. 

 coraco-brachialis, suppUes a branch to this muscle and terminates in the 

 biceps brachii and mastoido-humerahs. (The biceps may now be tran- 

 sected.) It gives off a branch which extends towards the scapulo-humeral 

 joint and is distributed to the biceps brachii and its synovial tendon sheath. 

 Occasionally the A. circumflexa htimeri anterior is a small vessel supplying 

 only the coraco-brachialis. 



