262 ANATOMY OF THE RABBIT 



The axillary artery (a. axillaris), the continuation of the sub- 

 clavian, crosses from the first rib to the medial surface of the 

 humerus, after reaching which it is called the brachial artery. Its 

 branches are: 



(a) The transverse scapular (suprascapular) artery (a. trans- 

 versa scapulae). It arises from the anterior wall and, 

 taking a position dorsal to the clavicle, accompanies the 

 p. tertius and pectoscapularis to the front of the shoulder, 

 where, under cover of these muscles, it passes into the 

 supraspinatus muscle (3, e). 



(b) The thoracoacromial artery (a. thoracoacromialis). It 

 arises from the ventral wall or in common with (c), passes 

 between the pectorales tertius and quartus, then between 

 the p. primus and the cleidohumeralis. It distributes 

 branches to these muscles and, taking a position ventral 

 to the clavicle, passes to the platysma and the skin. 



(c) The lateral (long) thoracic artery (a. thoracalis lateralis) 

 arises from the posterior wall or in common w4th (&), 

 distributes branches chiefly to the p. secundus, and sends 

 a long superficial branch, the external thoracic artery, 

 backward through the cutaneus maximus muscle. This 

 vessel is usually conspicuous in the female, where it dis- 

 tributes external mammary branches to the mammary 

 glands. It anastomoses posteriorly with the superficial 

 epigastric branch of the femoral. 



(d) The subscapular artery (a. subscapularis) is a large branch 

 given off from the distal portion of the axillary artery. It 

 distributes branches to the subscapularis muscle, and sends 

 a thoracodorsal branch into the latissimus dorsi. Perfo- 

 rating the teres major muscle near the axilla, it appears on 

 the lateral surface of the shoulder, where it sends a large 

 branch into the inferior portion of the trapezius, and a 

 second into the cutaneus maximus. The latter vessel 

 supplies the proximal end of the long head of the triceps, 

 but its chief portion passes backward uniting with an 

 anterior superficial branch of the iliolumbar, and thus 

 forming one of three anastomoses covering the abdominal 



