THE COMMON ILIAC VEINS — THE VEINS OF THE PELVIC LIMB 597 



ventrally and a little to the right, and reaches the portal fissure of the liver. Here it 

 divides into three branches which enter the liver and ramify in the substance of 

 the gland like an artery, terminating in the lobular capillaries. From the lobules 

 the blood passes into the hepatic veins and through these to the posterior vena 

 cava. Thus the blood which is distributed to the stomach, nearly the entire in- 

 testinal tract, the pancreas, and the spleen, passes through two sets of capillaries 

 prior to its return to the heart, viz., the capillaries of these viscera and of the liver. 



1. The anterior mesenteric vein (V. mesenterica cranialis) is the largest of 

 the portal radicles. It is situated to the right of the artery of like name, and its 

 tributaries correspond in general to the branches of the artery. Usually a single 

 colic vein corresjxjnds to th(^ two arteries of the right portions of the colon. 



2. The posterior mesenteric vein (V. mesenterica caudalis) is the smallest of 

 the radicles of the portal. It accompanies the artery in the colic mesentery and its 

 rectal branches anastomose with those of the internal pudic vein. 



3. The splenic vein (V. lienalis) is the very large satellite of the splenic arter3\ 

 It is formed by the union of two radicles at the base of the spleen. On leaving the 

 hilus of the spleen it passes inward l)etween the anterior pole of the left kidney and 

 the saccus csecus of the stomach and above the left end of the pancreas, receives 

 commonly the posterior gastric vein (V. gastrica caudalis), and unites with the 

 anterior mesenteric at the posterior border of the pancreas. 



The collateral tributaries of the portal veins are as follows: 



(1) Pancreatic veins (Rami pancreatici). 



(2) The gastro-duodenal vein (V. gastroduodcnalis) corrcsjionds mainly to the 

 extrahepatic branches of the hepatic artery. 



(3) The anterior gastric vein (V. gastrica cranialis) joins the portal at the 

 portal fissure. 



THE COMMON ILIAC VEINS (Fig. 456) 



These (V. iliacse connnunes) are two very large Ijut short trunks which result 

 from the union of the internal and external iliac veins of each side at the sacro- 

 iliac articulation. The left one is the longer and crosses obliquely over the terminal 

 part of the aorta. The chief tributaries of each are as follows: 



1. The last lumbar vein. 



2. The circumflex iliac veins (Vv. circumflexse ilium profundse) are the two 

 satellites of each corresponding artery, on either side of which they are placed. 

 They may open directly into the posterior vena cava or into the external iliac vein. 



3. The ilio-lumbar vein (V. iliolumbalis) may open into the common iliac, 

 the external iliac, or the internal iliac vein. 



THE INTERNAL ILIAC VEINS 



The internal iliac or hypogastric veins (Vv. hypogastrics), right and left, are 

 usually formed by the confluence of lateral sacral, gluteal, and internal pudic 

 veins. The obturator vein may open into them also. They are short trunks and 

 are smaller than the external iliac veins. The tributaries correspond in general to 

 the branches of the three arteries of like names. The internal pudic veins receive 

 affluents from the venous plexuses of the prepuce and penis in the male; of the 

 mammary gland, vulva, vagina, and vestibular bulb in the female. 



THE VEINS OF THE PELVIC LIMB 



The external iliac vein (V. iliaca externa) (Figs. 450, 451) lies behind the cor- 

 responding artery at the brim of the pelvis. It is the upward continuation of the 

 femoral vein, and unites at the sacro-iliac joint with the internal iliac to form the 

 common iliac vein. Its tributaries are as follows: 



