

THE AXILLARY ARTERY 



587 



major; on its lateral side is the Coracobrachialis, and on its medial or thoracic side, the axillary 

 vein. The nerves of the brachial plexus bear the following relations to this part of the artery: 

 on the lateral side are the lateral head and the trunk of the median, and the musculocutaneous 

 for a short distance; on the medial side the ulnar (between the vein and artery) and medial brachial 

 cutaneous (to the medial side of the vein); in front are the medial head of the median and the 

 medial antibrachial cutaneous, and behind, the radial and axillary, the latter only as far as the 

 lower border of the Subscapularis. 



Collateral Circulation after Ligature of the Axillary Artery. If the artery be tied above the 

 origin of the thoracoacromial, the collateral circulation will be carried on by the same branches 

 as after the ligature of the third part of the subclavian; if at a lower point, between the 

 thoracoacromial and the subscapular, the latter vessel, by its free anastomosis with the trans- 

 verse scapular and transverse cervical branches of the subclavian, will become the chief agent 

 in carrying on the circulation ; the lateral thoracic, if it be below the ligature, will materially contrib- 

 ute by its anastomoses with the intercostal and internal mammary arteries. If the point included 

 in the ligature is below the origin of the subscapular artery, it will most probably also be below 

 the origins of the two humeral circumflex arteries. The chief agents in restoring the circulation 

 will then be the subscapular and. the two humeral circumflex arteries anastomosing with the 

 a. profunda brachii. 



FIG. 523. The axillary artery and its branches. 



Branches. The branches of the axillary are: 



ri , TT . i , m, . , . ( Thoracoacromial. 



from first part, Highest Inoracic. f rom second part IT , , rpi 



fSubscapular. 



From third part < Posterior Humeral Circumflex. 

 (Anterior Humeral Circumflex. 



1. The highest thoracic artery (a. thoracalis suprema; superior thoracic artery} 

 is a small vessel, which may arise from the thoracoacromial. Running forward 

 and medialward along the upper border of the Pectoralis minor, it passes between 

 it and the Pectoralis major to the side of the chest. It supplies branches to these 





