ANATOMY OF THE FOWL 



33 



Fig. 



The structure of the l)lood vessels are the same as in main- 



iiials. The puhiionary artery emerges from the right ventri- 

 cle, is short and divides into a right and a left branch, whicli 



go to the respective lungs. 



The aorta emerges from the left ventricle, is short and 



gives off the right and left coronaries 



and bifurcates into the l)rachioce- 



phalic dexter (the right branch) and 



the brachiocephalic sinister (the left 



branch). The brachiocephalic dexter 



gives off the posterior aorta which 



winds round the right bronchus and 



passes along the lower portions of the 



vertebrae. It then bifurcates to form 



the right carotid and right subclavian 



arterv. Farther alons: the left and 



right carotids conununicate and at 



this point the thyroid gland is located. 



The brachiocephalic sinister bifurcates 



into the left carotid and the left sub- 

 clavian artery. 



In some species of birds the two 



carotids unite and form one carotid 



called the carotid primaria. The 



carotids give off branches to adjacent 

 parts as they pass toward the head, 

 given off, which supplies the vertebrae. At the level of 

 the head each carotid divides into two branches, one sup- 

 plying the brain, eyeball and adjacent parts, and the other 

 the remainder of the cranial structures. The two sub- 

 clavian arteries each give off a sterno-clavicularis which sup- 

 plies the anterior sternal region up to the shoulder, where 

 it divides into arteries which supply the breast and the arm. 

 The thoracic cranialis is also given off' from the brachio- 

 cephalic as well as the thoracic caudalis, the latter supplying 

 the large breast muscle. At about this point there is also a 

 branch, the internal mammary, given off and which follows 

 along the inner border of the sternum. The axillary artery 

 may be considered a continuation of the brachiocephalic; it 

 supplies the muscles of the wing system. 



The posterior aorta extends along the lower borders of the 

 vertebra as far as the pelvis. It gives off on its way inter- 

 costals, which pass, one along the posterior border of each 

 rib and are disposed of similar to those of mammals. It also 

 gives off a celiac axis supplying the stomach, liver and spleen, 

 two mesenteric branches (mesentericus cranialis and m. 



Heart of Fowl with 

 (. Its Main Branches. 



'' 1, cartoid artery; 2, sterno- 

 clavicularus artery; 3, axil- 



'lary artery; 4, thoracic cran- 

 ialis artery; 5, thoracic cau- 

 dalis; 6, posterior aorta; LA, 

 left auricle; RA, right auri- 

 cle; LV, left ventricle; RV, 

 riglit ventricle. 



A vertebral artery is 



