Inferior mesenteric artery
Unpaired trunk · Hindgut T12–L2
Smallest of the three trunks, arising at L3 about 3–4 cm above the bifurcation and descending retroperitoneally to the left before continuing over the left common iliac vessels as the superior rectal artery. Artery of the hindgut: distal third of the transverse colon to the anal canal above the pectinate line.
Traced from the start
- Abdominal aorta
- Inferior mesenteric artery
Detail
- Level
- L3, behind the 3rd part of the duodenum
- Supplies
- Hindgut: distal 1/3 transverse colon, descending and sigmoid colon, rectum, upper anal canal
- Branches
- Left colic, 2–4 sigmoid, superior rectal (continuation)
- Referred pain
- Suprapubic / hypogastric, T12–L2 via least and lumbar splanchnic nerves
When it goes wrong
IMA ligated at open AAA repair, covered by an endograft, or occluded by atheroma
Usually silent because the marginal artery and arc of Riolan carry SMA blood into the hindgut; when that arcade is deficient, sigmoid ischaemic colitis follows
High ligation of the IMA at its origin for rectal cancer surgery
Descending and sigmoid colon depend entirely on retrograde marginal flow from the middle colic; an interrupted arcade leads to an ischaemic, leaking anastomosis
Practise this structure
1 question in the bank tagged Hindgut.