1036 



THE VASCULAE SYSTEM. 



intercostal vein. The other venous channels of the cranium and the head and neck and the 

 upper extremities are later formations. 



The right duct of Cuvier forms the inferior half of the superior vena cava, and the left duct 

 of Cuvier becomes the oblique vein of the left atrium. 



The posterior cardinal veins take part in the formation of the inferior vena cava, the azygos 

 herniazygos, and accessory hemiazygos veins, and the hypogastric veins. The right subcardinal 

 takes part in the formation of the inferior vena cava, and an anastomosis between the right and 

 left subcardinal veins forms a large part of the left renal vein. 



The Vitelline and Umbilical Veins and their Association with the Formation of the 

 Portal System and the Upper End of the Inferior Vena Cava. The vitelline veins, left and 



Upper or cephalic part of inferior vena cava 



Right vena revehen 



Sinus venosus 



Left lateral 

 mbilieal vein 



Right branch oP 

 portal vein 



Atrophied part of right- \ 

 vitelline vein V 



,, Left vena reveheus 



jjPjr-- Ductus venosus 



Left branch of portal vein 



_ Atrophied part of left 

 vitelline vein 



"" Left lateral umbilical vein 



- - Superior uiesenteric vein 



Right vitelline vein 

 3 



Upper or cephalic part of inferior vena cava 



j Left hepatic vein 

 Right hepatic vein JJ^J_ Ductus ven osus 



Azygos vein 



Sinus venosus 

 \ 



Left lateral 

 '" umbilical 

 vein 



Left lateral 

 umbilical vein 



" Left vitelline vein 

 N Right vitelline vein 

 2 



Right renal vein 

 Part of inferior vena 

 cava derived from right 

 posterior cardinal vein 



Left renal vein 

 Left spermatic vein 



Left suprarenal vein 



Liver 



Inferior vena cava ; 



down growth from 

 upper part 

 Left branch of 

 portal vein 



Right branch of portal vein 

 _. Left branch of portal vein 

 Left lateral 

 umbilical vein 



Part of inferior vena 

 cava formed from 

 right subcardinal vein 



Splenic vein 



Superior mesenteric 

 vein 



\ Right vitelline vein 

 Left renal vein 



PIG. 833. SCHEMATA, showing four stages of the development of the portal system and 

 part of the inferior vena cava. 



right, pass over the wall of the yolk-sac, and, later, along the sides of the vitello-intestinal duct 

 and the duodenum, towards the caudal end of the heart. For a time each unites with the corre- 

 sponding lateral umbilical vein to form a common stem, but at a later period each vitelline vein 

 opens separately into the corresponding cornu of the sinus venosus of the heart. 



The umbilical veins are three in number the vena umbilicalis impar, which passes first along 

 the body stalk, and later along the umbilical cord, and divides into the right and left lateral 

 umbilical veins, which run, in the edges of the body wall, along the margin of the umbilical orifice, 

 to their union, first, with the corresponding vitelline veins, and later with the corresponding 

 cornua of the sinus venosus of the heart. 



On their way to the heart, both the vitelline and the lateral umbilical veins pass through 



