Origin and location
The superior rectal artery originates from the inferior mesenteric artery (a. mesenterica inferior). The inferior mesenteric artery arises from the anterior surface of the lower third of the abdominal aorta at the level of the third lumbar vertebra (LIII) and runs retroperitoneally.
A. rectalis superior is the terminal branch of this trunk. The inferior mesenteric artery also gives off the left colic and sigmoid arteries. The superior rectal artery runs within the root of the mesentery and courses toward the ampullary part of the rectum.
Blood supply to the rectum and anastomoses
The rectum receives blood supply from five arteries. The superior rectal artery is unpaired; the middle and inferior rectal arteries are paired.
It forms anastomoses:
- With the inferior sigmoid artery.
- With the middle rectal artery (a. rectalis media), a branch of the internal iliac artery (a. iliaca interna).
Vascularization feature: only a single first-order arcade — a marginal or parallel vessel — is formed along the mesenteric border of the intestine.
Topography and adjacent structures
The upper part of the rectum is covered by peritoneum on all sides (intraperitoneally), while the supra-ampullary, or rectosigmoid, part sometimes has a mesentery (mesorectum).
Extraorgan veins run alongside the arteries and form the superior and inferior mesenteric veins. The inferior mesenteric vein (v. mesenterica inferior) runs to the left of the duodenojejunal flexure (flexura duodenojejunalis) beneath the body of the pancreas and drains into the splenic vein. The rectal veins form the rectal venous plexus, which participates in the portosystemic anastomotic system.
Lymphatic drainage and clinical significance
Regional lymph nodes are located along a. rectalis superior. When a tumor is localized in the sigmoid colon, regional lymph nodes are located, in particular, along a. rectalis superior.
In the treatment of cancer of the distal third of the sigmoid colon, resection of the sigmoid colon with transabdominal resection of the rectum is recommended, or a Hartmann procedure if an anastomosis cannot be created. The vascular stage involves ligation of the inferior mesenteric artery (a. mesenterica inferior) at its base or directly distal to the origin of the left colic artery (a. colica sinistra).
Class and exam questions
Is the superior rectal artery paired?
No, it is an unpaired artery. The middle and inferior rectal arteries are paired.
Of which artery is it a branch?
It is the terminal branch of the inferior mesenteric artery (a. mesenterica inferior), which arises from the anterior surface of the lower third of the abdominal aorta at the LIII level.
Which arteries does it anastomose with?
The superior rectal artery anastomoses with the inferior sigmoid artery and the middle rectal artery (a branch of a. iliaca interna).
What else to study on this topic
- Inferior mesenteric artery (a. mesenterica inferior)
- Middle rectal artery (a. rectalis media)
- Blood supply to the rectum
- Portosystemic anastomoses of the rectum
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