1 — Hepatic portal vein; 2 — Splenic vein; 3 — Inferior mesenteric vein; 4 — Superior rectal vein; 5 — Middle rectal veins; 6 — Inferior rectal veins; 7 — Internal pudendal vein; 8 — Internal iliac vein; 9 — Common iliac vein; 10 — Inferior vena cava
