Middle rectal veins

The middle rectal veins (or middle hemorrhoidal vein) take origin in the hemorrhoidal plexus and receive tributaries from the bladder, prostate, and seminal vesicle.

Middle rectal veins
Scheme of the anastomosis of the veins of the rectum
Details
Drains from	Rectum
Drains to	Internal iliac vein
Artery	Middle rectal artery
Identifiers
Latin	venae rectales mediae
TA98	A12.3.10.018
TA2	5030
FMA	70912
Anatomical terminology [edit on Wikidata]

They run lateralward on the pelvic surface of the levator ani to end in the internal iliac vein. Veins superior to the middle rectal vein in the colon and rectum drain via the portal system to the liver. Veins inferior, and including, the middle rectal vein drain into systemic circulation and are returned to the heart, bypassing the liver.^[1]

References

This article incorporates text in the public domain from page 676 of the 20th edition of Gray's Anatomy (1918)

1. van Hoogdalem, Edward; de Boer, Albertus G.; Breimer, Douwe D. (July 1991). "Pharmacokinetics of rectal drug administration, Part I. General considerations and clinical applications of centrally acting drugs". Clinical Pharmacokinetics. 21 (1): 14. doi:10.2165/00003088-199121010-00002. ISSN 0312-5963. Retrieved 18 March 2024. The superior rectal vein, perfusing the upper part of the rectum, drains into the portal vein and subsequently into the liver On the other hand, the middle and inferior rectal veins drain the lower part of the rectum and venous blood is returned to the inferior vena cava.