702 MANUAL OF PHYSIOLOGY. 



From the branches of the aorta? arise two large vessels, which, 

 running along the allantois, spread out over the chorion, being 

 especially directed to the upper part of this membrane ; these are 



FIG. 287. 



Diagram of the vascular system of a human foetus. (Huxley.) H. Heart. 

 T.A. Aortic trunk, c. Common carotid artery. c / . External carotid artery. 

 c/'. Internal carotid artery, s. Subclavian artery, v. Vertebral artery. 1, 

 2,3,4,5. Aortic arches. A'. Dorsal aorta. 1. Omphalo-mesenteric artery. 

 dv. Vitelline duct. o / '. Omphalo-mesenteric vein. v'. Umbilical vesicle. 

 vp. Portal vein. L. Liver, uu. Umbilical arteries. u // u" '. Their endings 

 in the placenta. u f . Umbilical vein. Dv. Ductus venosus. vh. Hepatic 

 vein. cv. Vena cava inferior, vil. Iliac veins, az. Vena azygos. vc. Pos- 

 terior cardinal vein. DC. Duct of Cuvier. P. Lungs. 



the umbilical or hypogastric arteries, which carry the blood from 

 the aortte to the foetal placenta. 



Veins arise from the terminal networks of these arteries, and 

 combine to form the two umbilical veins. The umbilical veins 

 take a similar course to the arteries, and convey the blood to the 

 venous trunk formed by the junction of the omphalo-rnesenteric 

 veins. 



