It receives the following branches ([Fig. 126]): lumbar, iliolumbalis (v), spermatica interna (u), renal (t), adrenolumbalis (s), phrenic, and hepatic veins. All but the last two named accompany the arteries of the same name.

V. phrenica.—The phrenic veins gather the blood from the diaphragm and empty into the vena cava as it penetrates the diaphragm.

V. hepatica.—The hepatic veins vary in number. They gather the blood from the liver (sent in by the portal vein and hepatic arteries) and enter the vena cava just caudad of the diaphragm.

Vena Portæ. The Portal Vein

([Fig. 131]).—The portal vein is the large vein carrying the blood from the abdominal viscera to the liver. Within the liver the portal vein breaks up into capillaries; these collect to form the hepatic veins, which enter the vena cava inferior. The portal vein (a) is formed near the pyloric end of the stomach (1) by the union of the superior mesenteric (b) and gastrosplenic (c) veins and passes thence along the ventral border of the foramen epiploicum (foramen of Winslow) to the liver (2), where it divides, going to the lobes of the liver. On its way to the liver it may receive the pancreaticoduodenalis (d), gastroepiploica (e), and coronaria ventriculi (f). These may unite with the portal separately, or any two or all three may unite to form a single trunk before entering the portal vein.

1. V. coronaria ventriculi (f) gathers the blood from the lesser curvature of the stomach and anastomoses with the gastrosplenic veins. It usually empties into the portal vein near the pylorus.

2. V. pancreaticoduodenalis (d) receives the blood from the pancreas and first part of the duodenum, and empties into the vena portæ near to or with the preceding.

[Fig. 132].—Portal Vein.

a, portal vein; b, superior mesenteric; c, gastrosplenic; d, pancreaticoduodenalis; e, gastroepiploica; f, coronaria ventriculi; g, h, i, branches of gastrosplenic; j, inferior mesenteric. 1, stomach; 2, liver; 3, duodenum; 4, spleen.