| Inferior mesenteric artery | |
|---|---|
 Sigmoid colon andrectum, showing distribution of branches of inferior mesenteric artery and theiranastomoses. (Inferior mesenteric artery labeled at center.) | |
 Abdominal part of digestive tube and its attachment to the primitive or common mesentery. Human embryo of six weeks. (Inferior mesenteric artery labeled at bottom right.) | |
| Details | |
| Precursor | Vitelline arteries |
| Source | Abdominal aorta |
| Branches | Left colic artery,sigmoid branches,superior rectal artery |
| Vein | Inferior mesenteric vein |
| Supplies | Large Intestine |
| Identifiers | |
| Latin | arteria mesenterica inferior |
| MeSH | D017537 |
| TA98 | A12.2.12.069 |
| TA2 | 4291 |
| FMA | 14750 |
| Anatomical terminology | |
Inhuman anatomy, theinferior mesenteric artery (IMA) is the third main branch of theabdominal aorta and arises at the level ofL3, supplying thelarge intestine from the distaltransverse colon to the upper part of theanal canal. The regions supplied by the IMA are thedescending colon, thesigmoid colon, and part of therectum.[1]
The IMA arises from the anterior aspect of theabdominal aorta.[2][3]
The vertebral level of its origin is situated at L3 (subcostal plane),[2][3] below the origins of the tworenal arteries,[3] 3.8 cm (1 and a half inches) above theaortic bifurcation,[3][2] at the level of theumbilicus (transumbilical plane), and posterior to the inferior border of the horizontal (III) part of theduodenum.[2]
Along its course, the IMA has the following branches:[1][4][3]
| Branch | notes |
|---|---|
| left colic artery | suppliesdescending colon |
| sigmoid branches | the most superior being described as 'the superior sigmoid artery' |
| superior rectal artery | effectively the terminal branch of the IMA (the continuation of the IMA after all other branches) |
All these arterial branches further divide intoarcades which then supply thecolon at regular intervals.
The IMA is accompanied along its course by a similarly namedvein, theinferior mesenteric vein, which drains into thesplenic vein.[1] The IMV drains to theportal vein and does therefore not fully mirror the course of the IMA.[contradictory][1][4][3]
Proximally, its territory of distribution overlaps (forms awatershed) with themiddle colic artery, and therefore thesuperior mesenteric artery. The SMA and IMA anastomose via themarginal artery of the colon (artery of Drummond) and viaRiolan's arcade (also called the "meandering artery", an arterial connection between the left colic artery and the middle colic artery). The territory of distribution of the IMA is more or less equivalent to the embryonichindgut.[1][4]
The IMA and/or its branches must be resected for a left hemicolectomy.[5]
Ahorseshoe kidney, a common (1 in 500) anomaly of the kidneys, will be positioned below the IMA.[6][7]
