This vessel, as we have previously pointed out, is a branch of the right axillary and runs forward beneath the trachea until it reaches the entrance to the chest, where it divides into a right and left carotid artery.

Fig. 193. - Diagram of Circulation.

A, A, Posterior Vena Cava. B, Anterior Vena Cava. C, Pulmonary Artery. D, Hepatic Veins. E, Vena Porta. F, Renal Vein. G, Spermatic Vein.

H, Posterior Mesenteric Vein. 1 Pulmonary Vein.

2 Anterior Aorta. 3, 4 Posterior Aorta. 5 Splenic Artery. 6 Hepatic Artery. 7 Gastric Artery.

8 Anterior Mesenteric Artery. 9 Renal Artery.

10 Spermatic Artery. 11 Posterior Mesenteric Artery. L.K., Left Kidney. R.K., Right Kidney, dia., Diaphragm, e.l. , Right Lung. L.L., Left Lung. K.V., Right Ventricle. L.v., Left Ventricle. STOM., Stomach. SP., Spleen.