Cardiovascular system · Abdomen
Inferior mesenteric artery !
The inferior mesenteric artery is a branch of the lower aorta that feeds the left part of the colon, the sigmoid colon and the upper rectum.
Opens in the Durgical app, no sign-up needed.
What it is
The smallest of the three gut arteries, from the aorta at L3, with the left colic, sigmoid and superior rectal branches.
What it does
Supplies the last third of the transverse colon, the descending and sigmoid colon and the upper rectum.
Key facts
- Origin
- Anterior aorta at L3, behind D3, about 3–4 cm above aortic bifurcation
- Branches
- Left colic, sigmoid arteries (2–4), superior rectal artery (terminal)
- Supplies
- Hindgut: distal third of transverse colon to upper anal canal (above pectinate line)
Relations
- Course
- From the aorta behind the third or fourth part of the duodenum it runs down and to the left behind the peritoneum, crosses the left common iliac artery and continues into the root of the sigmoid mesocolon as the superior rectal artery
- Medial
- Aorta and the aortic nerve plexus, which surrounds its origin and continues down as the superior hypogastric plexus
- Lateral
- Inferior mesenteric vein, to its left, which runs up on its own to join the splenic vein behind the pancreas
- Behind
- Left psoas major and left common iliac artery; the left ureter and left gonadal vessels lie behind and to the left
How to find it
At surgery it is found by drawing the sigmoid colon and its mesentery to the right: the artery leaves the front of the aorta a few centimetres above the aortic bifurcation, just below the third part of the duodenum, and runs down and to the left behind the peritoneum. The inferior mesenteric vein lies to its left, and the left ureter and gonadal vessels lie behind it.
On imaging
CT angiography shows whether it is open and how large the arc of Riolan is. Mesenteric angiography of its branches can locate bleeding from the left colon. After endovascular aneurysm repair, a patent inferior mesenteric artery can keep filling the sac backwards (type II endoleak).
Common problems
- Mesenteric ischemia: a clot or narrowing starves the gut; severe pain 'out of proportion' to the examination. An emergency.
How it is diagnosed
CT angiography.
Treatment
- Restore flow (catheter or surgery) and remove dead bowel.
Clinical notes
- Open aortic aneurysm repair often ties it; colonic ischemia follows when collaterals are poor, so it is sometimes reimplanted
- The hypogastric nerves around its origin can be injured at high ligation, leading to ejaculatory and bladder dysfunction
- Ischemic colitis targets the watershed areas, especially the splenic flexure, in low-flow states
Anatomical variants
- Rarely doubled or absent
- The left colic artery may be absent or share a trunk with the sigmoid arteries
Development
The artery of the hindgut, from a vitelline artery; its territory ends at the pectinate line, below which branches of the internal iliac system take over.
Related conditions
- Ischaemic colitis
- Colorectal cancer
- Diverticular disease and diverticulitis
- Sigmoid volvulus
- Ulcerative colitis
Test yourself
Think of the answer, then tap the question to see it.
At what level does the inferior mesenteric artery arise, and what are its branches?
From the front of the aorta at L3, behind the third part of the duodenum; left colic, 2–4 sigmoid arteries and the superior rectal artery (terminal).
What territory does the inferior mesenteric artery supply?
The hindgut: distal third of the transverse colon to the upper anal canal, above the pectinate line.
What are the two watershed areas of the colon?
Griffiths point at the splenic flexure (between SMA and IMA territories) and Sudeck point at the rectosigmoid (between the last sigmoid and superior rectal arteries).
Why is occlusion of the inferior mesenteric artery in an aortic aneurysm often silent?
The marginal artery and the arc of Riolan bring blood from the superior mesenteric artery.
How can a patent inferior mesenteric artery cause a type II endoleak?
After endovascular aneurysm repair it can keep filling the aneurysm sac backwards.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- arteria mesenterica inferior; arteriae sigmoideae; arteria anorectalis superior TA2 4291
- Official Spanish (DeCS)
- Arteria mesentérica inferior DeCS D017537
- English (TA2)
- Inferior mesenteric artery
- Also called
- superior rectal artery · superior hemorrhoidal artery · IMA · arteria mesenterica caudalis
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Abdomen and Pelvis: Inferior Mesenteric Artery; Anatomy of the Human Body (20th ed.): The Abdominal Aorta (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain.
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Representative model, for educational purposes only.
