592 THE ARTERIES. 



the subscapular and the two circumflex arteries anastomosing with the superior prof'unda from 

 the brachial. 



BRANCHES OF THE AXILLARY ARTERY. 

 The branches of the axillary artery are 



r, -? . f Superior Thoracic. ^ -, . ( Long Thoracic. 



From first part | A( omial Thoracic From second part j Alar g Thoracic 



( Subscapular. 



From third parti Anterior Circumflex. 

 (Posterior Circumflex. 



The superior thoracic is a small artery which arises from the axillary sepa- 

 rately or by a common trunk with the acromial thoracic. Running forward and 

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

 Pectoralis major to the side of the chest. It supplies these muscles and the parietes 

 of the thorax, anastomosing with the internal mammary and intercostal arteries. 



The acromial thoracic is a short trunk which arises from the fore part of the 

 axillary artery. Projecting forward to the upper border of the Pectoralis minor, 

 it divides into three sets of branches thoracic, acromial, and descending or 

 humeral. The thoracic branches, two or three in number, are distributed to the 

 Serratus magnus and Pectoral muscles, anastomosing with the intercostal 

 branches of the internal mammary. The acromial branches are directed outward 

 toward the acromion, supplying the Deltoid muscle, and anastomosing, on the sur- 

 face of the acromion, with the suprascapular and posterior circumflex arteries. 

 The humeral branch passes in the space between the Pectoralis major and Deltoid 

 in the same groove as the cephalic vein, and supplies both muscles. The artery 

 also gives off a very small branch, the clavicular, which passes upward to the Sub- 

 clavius muscle. 



The long thoracic (external mammary') passes downward and inward along the 

 lower border of the Pectoralis minor to the side of the chest, supplying the Serra- 

 tus magnus, the Pectoral muscles, and mammary gland, and sending branches 

 across the axilla to the axillary glands and Subscapularis ; it anastomoses with 

 the internal mammary and intercostal arteries. An accessory external mammary 

 branch is often found running to the chest behind the long thoracic. 



The alar thoracic is a small branch which supplies the glands and areolar 

 tissue of the axilla. Its place is frequently supplied by branches from some of the 

 other thoracic arteries. 



The subscapular, the largest branch of the axillary artery, arises opposite the 

 lower border of the Subscapularis muscle, and passes downward and backward 

 along its lower margin to the inferior angle of the scapula, where it anastomoses 

 with the long thoracic and intercostal arteries and with the posterior scapular. 

 About an inch and a half from its origin it gives off a large branch, the dorsalis scap- 

 ulae, and terminates by supplying branches to the muscles in the neighborhood. 



The dorsalis scapulae is given off from the subscapular about an inch from its 

 origin, and is generally larger than the continuation of the vessel. It curves round 

 the axillary border of the scapula, leaving the axilla through the space between 

 the Teres minor above, the Teres major below, and the long head of the Triceps 

 externally (Fig. 361), and enters the infraspinous fossa, where it anastomoses with 

 the posterior scapular and suprascapular arteries.' In its course it gives off two 

 sets of branches : one enters the subscapular fossa beneath the Subscapularis, 

 which it supplies, anastomosing with the posterior scapular and suprascapular 

 arteries ; the other is continued along the axillary border of the scapula, between 

 the Teres major and minor, and, at the dorsal surface of the inferior angle of the 

 bone, anastomoses with the posterior scapular. In addition to these, small branches 

 are distributed to the back part of the Deltoid muscle and the long head of the 

 Triceps, anastomosing with an ascending branch of the superior profunda of the 

 brachial. 



