Inferior Mesenteric Artery (Full)

arteria mesenterica inferior

The IMA supplies the hindgut derivatives from the transverse-descending colon junction to the upper rectum. It is ligated in sigmoid and left colon surgery — preserved near the aorta in elective left hemicolectomy to maintain the marginal artery of Drummond (the arcade connecting IMA to SMA via the left colic-middle colic anastomosis). The IMA origin is the landmark for aortic bifurcation and is at risk in EVAR.

Region: Abdomen

Anatomical Data

Origin, Insertion & Supply

Origin	Abdominal aorta at the L3 level (approximately 3-4 cm above the aortic bifurcation)

Clinical Relevance

Clinical Notes

The marginal artery of Drummond and the arc of Riolan (direct SMA-IMA anastomosis) protect the sigmoid from ischaemia after IMA ligation. The Sudeck critical point between the last sigmoid artery and the superior rectal artery has limited collateral supply — sigmoid colon excision leaving the Sudeck point at risk can produce sigmoid ischaemia.

Pathology

Common Injuries & Conditions

IMA Ligation in Colorectal Surgery

IMA division in sigmoid resection relying on marginal artery collaterals for sigmoid viability managed by preserving the high IMA ligation above the left colic takeoff.