222 ANATOMY OF THE DOMESTIC FOWL 



clavicularis gives off the sternal artery, which enters by the side of the 

 supra-coracoid muscle and the anterior rim of the sternum. It is 

 distributed to the inner surface and over the air-sac. Another 

 outside branch passes the posterior end of the crista sterna and 

 supplies the large breast muscles. 



The clavicular artery (Fig. 73, No. 8) accompanies the clavicle to 

 the shoulder-joint. 



The acromial artery is given off from the sterno-clavicularis on 

 the ligament near the shoulder-joint. 



2. The thoracic artery branches from the subclavian artery (Fig. 

 70, No. 4). The thoracic artery gives off the following branches: 



The internal mammary, or internal thoracic artery (Fig. 73, No. 16) 

 arises on the inner side of the sternum and extends downward and 

 backward, giving nutrient branches to the anterior vena cava and 

 to the diaphragm. At the point of the costo-sternal muscle it 

 divides into an inner and an outer branch. 



The inner branch supplies the costo-sternal muscle and extends 

 along the ribs and along their juncture with the breast-bone. It 

 finally extends posteriorly, giving numerous branches to the abdom- 

 inal muscles. The outer branch is distributed in a similar manner, 

 giving off branches to the diaphragm and to the abdominal muscles, 

 and anastomoses, on the surface of the abdominal muscles, with the 

 epigastric artery. 



The external thoracic artery (Fig. 73, No. 3), ramus superior, 

 supplies principally the large breast muscles. 



The inferior thoracic artery, external ramus inferior, passes along 

 the outside of the pectoralis major muscle, extends downward, 

 and gives off the arteria thoracica longa (subcutaneous thoracic). 

 This latter artery supplies the skin of the breast region. Other 

 branches are given off to the muscles of the breast and to the skin 

 of the region, and some finally anastomose with the branches of the 

 sternal artery. 



3. The axillary artery (Fig. 73, No. 12) extends out of the thoracic 

 cavity along with the brachial nerve plexus. It gives off the sub- 

 scapular is which supplies the muscles of the scapular region. The 

 axillary artery terminates as the brachialis which passes between 

 the biceps brachii and anconeus muscles downward along the 

 humeral shaft. It gives off the anterior humeral circumflex artery 

 and the brachialis profunda artery (Fig. 68, No. 3). It gives off 

 near the elbow-joint the ulnar and radial arteries. 



