Inferior mesenteric artery
Branch · L3 Hindgut 3 branches
Unpaired branch from the front of the aorta at L3, behind the third part of the duodenum, descending to the left to supply the hindgut: distal third of the transverse colon, descending and sigmoid colon, rectum and anal canal above the pectinate line. Branches: left colic, sigmoid arteries and its continuation, the superior rectal artery.
Traced from the start
- Abdominal aorta
- Inferior mesenteric artery
Detail
- Level
- L3
- Branches
- Left colic, 2–4 sigmoid, superior rectal
- Relations
- Inferior mesenteric vein runs to its left and drains to the splenic vein
- Collaterals
- Marginal artery (of Drummond) to the SMA; rectal arteries to the internal iliac
When it goes wrong
IMA ligated or covered during abdominal aortic aneurysm repair or left-sided colectomy
Usually tolerated through the marginal artery, but if it is deficient the sigmoid becomes ischaemic: bloody diarrhoea and left-sided pain in the first post-operative days
Low-flow state (shock, heart failure, dialysis) in an atherosclerotic patient
Ischaemic colitis at the watershed zones of the splenic flexure and rectosigmoid: crampy left-sided pain then bloody diarrhoea, 'thumbprinting' of the colon on imaging
Practise this structure
1 question in the bank tagged Mesenteric Arterial Supply.