Superior anorectal artery

At a glance

English

Superior anorectal artery

Latin (TA2)

Arteria anorectalis superior

System

Artery

Region

Trunk

Side

Single, on the midline

About the superior anorectal artery

The superior anorectal artery, better known as the superior rectal artery, is the end of the inferior mesenteric artery. Once that vessel has given its left colic and sigmoid branches, it crosses the left common iliac vessels at the pelvic brim and changes its name. It then descends into the pelvis in the root of the sigmoid mesocolon, lying medial to the left ureter.

In front of the sacrum, at about the level of the third sacral vertebra, it splits into right and left branches that run down on either side of the rectum within the mesorectum. These divide further and pierce the muscular wall, running down in the submucosa to the anal canal as far as the pectinate line. In the lower rectum and anal canal they anastomose with the middle rectal arteries from the internal iliac arteries and the inferior rectal arteries from the internal pudendal arteries.

Because it is the hindgut artery for the rectum, the superior anorectal artery supplies the mucosa above the pectinate line, the part of the anal canal derived from endoderm. Its companion, the superior rectal vein, drains to the portal system, while the middle and inferior rectal veins drain to the systemic veins; the meeting of these veins makes the anorectal region a site of portosystemic anastomosis.

In resection of the rectum the artery is divided with the mesorectum, either at the origin of the inferior mesenteric artery or just below the left colic branch. The point where the last sigmoid branch leaves it has been described as a weak spot in the colonic arcades, though its importance is debated. Its branches feed the internal haemorrhoidal cushions, and they are the target of artery ligation procedures for haemorrhoids.

Course and supply

Arises from

The inferior mesenteric artery, of which it is the continuation after the last sigmoid branch, as it crosses the left common iliac vessels.

Ends in

Divides beside the rectum into right and left branches that run in the submucosa down to the pectinate line, anastomosing with the middle and inferior rectal arteries.

Supplies

Supplies the rectum and the upper part of the anal canal above the pectinate line.