B. Hepatic Portal System.
The anterior abdominal (fig. 1, a.a.v., and fig. 2, a.a.v.) is a median vein running on the under-surface of the ventral body-wall from the pelvic girdle to the liver. It is made by the union of the pelvic veins (fig. 2, pel.), which are the ventral branches of the femoral veins. It runs forward along the ventral body-wall until over the liver, where it runs down and breaks up into
the liver at the junction of its lobes. On its way it receives the vesical vein (fig. 2, v.) from the bladder, also two small veins from the skin above the bladder.
The hepatic portal vein is rather difficult to see owing to it being obscured by the pancreas, through which it runs. It is made up of gastric vein from the stomach, intestinal and spleenic veins from the intestines and spleen respectively. The two latter form the hepatic portal by uniting at the lower end of the pancreas, and after running towards the liver it is joined by the gastric vein. The hepatic portal then runs on and joins with a large branch of the anterior abdominal vein, the ramus descendens,* which runs down from where the anterior abdominal vein breaks up into the liver for a short distance between the lobes to meet the hepatic portal. Finally it runs into the liver.
[Footnote] * “Anatomy of the Frog,” Ecker, Eng. trans., 1889, p. 248, fig.164 (b).