302 VARIETIES OF THE AXILLARY ARTERY. 



The Superior thoracic (short) frequently arises by a common trunk with 

 the preceding; it runs along the upper border of the pectoralis minor, 

 and is distributed to the pectoral muscles and mammary gland, inosculat 

 ing with the intercostal and mammary arteries. 



The Inferior thoracic (long external mammary) descends along the 

 lower border of the pectoralis minor to the side of the chest. It is distri- 

 buted to the pectoralis major and minor, serratus magnus, and subscapu- 

 laris muscle, to the axillary glands and mammary gland ; inosculating 

 with the superior thoracic, intercostal, and mammary arteries. 



The Thoracica axillaris is a small branch distributed to the plexus of 

 nerves and glands in the axilla. It is frequently derived from one of the 

 other thoracic branches. 



The Subscapular artery, the largest of the branches of the axillary, runs 

 along the lower border of the subscapularis muscle, to the inferior angle 

 of the scapula, where it inosculates with the posterior scapular, a branch 

 of the subclavian. It supplies, in its course, the muscles on the under 

 surface and inferior border of the scapula, and the side of the chest. At 

 about an inch and a half from the axillary, it gives off a large branch, the 

 dorsalis scapula, which passes backwards through the triangular space 

 bounded by the teres minor, teres major, and scapular head of the triceps, 

 and beneath the infra- spinatus to the dorsum of the scapula, where it is 

 distributed, inosculating with the supra-scapular and posterior scapular 

 arteries. 



The Circumflex arteries wind around the neck of the humerus. The 

 anterior, very small, passes beneath the coraco-brachialis and short head 

 of the biceps, and sends a branch upwards along the bicipital groove to 

 supply the shoulder joint. 



The Posterior circumflex, of larger size, passes backwards through the 

 quadrangular space bounded by the teres minor and major, the scapular 

 head of the triceps and the humerus, and is distributed to the deltoid 

 muscle and joint. Sometimes this artery is a branch of the superior pro- 

 funda of the brachial. It then ascends behind the tendon of the teres 

 major, and is distributed to the deltoid without passing through the quad- 

 rangular space. The posterior circumflex artery sends branches to the 

 shoulder joint. 



Varieties of t/ie Axillary artery. The most frequent peculiarity of this 

 kind is the division of the vessel into two trunks of equal size : a muscular 

 trunk, which gives off some of the ordinary axillary branches and supplies 

 the upfper arm, and a continued trunk, wilich represents the brachial ar- 

 tery. The next most frequent variety is the high division of the ulnar 

 which passes down the arm by the side of the brachial artery, and superfi- 

 cially to the muscles proceeding from the inner condyle, to its ordinary 

 distribution in the hand. In this course it lies immediately beneath the 



muscle. 8. Its inner head. 9. The axillary artery. JO. The brachial artery; a dark 

 line marks the limit between these two vessels. 11. The thoracica acromialis artery 

 dividing into its three branches ; the number rests upon the coracoid process. 12. The 

 superior and inferior thoracic arteries. 13. The serratus magnus muscle. 14. The 

 subscapular artery. The posterior circumflex and thoracica axillaris branches are seen 

 in the figure between the inferior thoracic and subscapular. Th3 anterior circumflex 

 is observed, between the two heads of the biceps, crossing the ;aeck of the humerus. 

 15. The superior profunda artery. 16. The inferior profunda. 17. The anastomotica 

 magna inosculating inferiorly with the anterior ulnar recurrent. 18. The termination 

 of the superior profunda, inosculating with the radial recurrent in the interspace be- 

 tween the brachialis anticus and supinator longus. 



