Inferior Mesenteric Artery

arteria mesenterica inferior

The inferior mesenteric artery supplies the hindgut from the splenic flexure to the upper rectum, including the descending colon, sigmoid colon, and rectum. The watershed area between the SMA and IMA territories at the splenic flexure (Griffiths point) and between the IMA and internal pudendal artery territories at the rectosigmoid junction (Sudeck critical point) are sites of ischaemia during aortic surgery and haemodynamic compromise.

Region: Abdomen

Anatomical Data

Origin, Insertion & Supply

Origin	Abdominal aorta at L3, approximately 3 to 4 cm above the aortic bifurcation

Clinical Relevance

Clinical Notes

IMA ligation during abdominal aortic aneurysm repair or sigmoid colon surgery can cause ischaemic colitis at the watershed zones if collateral flow through the marginal artery of Drummond is inadequate. The superior rectal artery from the IMA is the main blood supply to the upper rectum and its sacrifice during low anterior resection for rectal cancer can contribute to anastomotic ischaemia.

Pathology

Common Injuries & Conditions

Ischaemic Colitis

Left colon ischaemia from IMA territory compromise during aortic surgery or haemodynamic shock, producing bloody diarrhoea and left-sided abdominal pain managed with supportive care or resection for full-thickness necrosis.