inferior mesenteric artery
{{short description|Branch of the abdominal aorta supplying part of the large intestine}}
{{Infobox artery
| Name = Inferior mesenteric artery
| Latin = arteria mesenterica inferior
| Image = Gray538.png
| Caption = Sigmoid colon and rectum, showing distribution of branches of inferior mesenteric artery and their anastomoses. (Inferior mesenteric artery labeled at center.)
| Image2 = gray985.png
| Caption2 = 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.)
| BranchFrom = Abdominal aorta
| BranchTo = Left colic artery, sigmoid branches, superior rectal artery
| Vein = Inferior mesenteric vein
| Precursor = Vitelline arteries
| Supplies =Large Intestine
}}
In human anatomy, the inferior mesenteric artery (IMA) is the third main branch of the abdominal aorta and arises at the level of L3, supplying the large intestine from the distal transverse colon to the upper part of the anal canal. The regions supplied by the IMA are the descending colon, the sigmoid colon, and part of the rectum.{{Cite book |title=Gray's anatomy: the anatomical basis of clinical practice|last=Standring |first=Susan |year=2016 |isbn=978-0-7020-5230-9 |edition=41st |publisher=Elsevier Limited |location=Philadelphia |oclc=920806541}}
Structure
= Origin =
The IMA arises from the anterior aspect of the abdominal aorta.
Its origin is situated at the L3 vertebral level (subcostal plane),{{Cite book |last=Sinnatamby |first=Chummy |title=Last's Anatomy |year=2011 |isbn=978-0-7295-3752-0 |edition=12th |page=246}} below the origins of the two renal arteries, 3-4 cm above the aortic bifurcation,{{Cite book |last1=Drake |first1=Richard L. |title=Gray's anatomy for students |last2=Vogl |first2=Wayne |last3=Mitchell |first3=Adam W. M. |last4=Gray |first4=Henry |date=15 November 2015 |publisher=Churchill Livingstone/Elsevier |isbn=978-0-7020-5131-9 |edition=3rd |location=Philadelphia, PA |oclc=881508489}} at the level of the umbilicus, and posterior to the inferior border of the horizontal (III) part of the duodenum.
=Branches=
Along its course, the IMA has the following branches:{{Cite book |last1=Moore |first1=Keith L. |title=Clinically oriented anatomy |last2=Dalley |first2=Arthur F. II |last3=Agur |first3=A. M. R. |date=13 February 2013 |publisher=Wolters Kluwer Health/Lippincott Williams & Wilkins |isbn=978-1-4511-1945-9 |edition=7th |location=Philadelphia |oclc=813301028}}
| class="wikitable"
! Branch !! notes | |
| left colic artery | supplies descending 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 into arcades which then supply the colon at regular intervals.
=Relations=
The IMA is accompanied along its course by a similarly named vein, the inferior mesenteric vein, which drains into the splenic vein. The IMV drains to the portal vein and does therefore not fully mirror the course of the IMA.{{Contradict-inline|reason=The IMV classically unites with the splenic vein to form the portal vein which needs to be clarified in text (cannot do this ad hoc since it may not be explicitly stated in currently cited sources - sources need to be checked before disambiguation, or new sources provided).|date=January 2023}}
= Distribution =
Proximally, its territory of distribution overlaps (forms a watershed) with the middle colic artery, and therefore the superior mesenteric artery. The SMA and IMA anastomose via the marginal artery of the colon (artery of Drummond) and via Riolan'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 embryonic hindgut.
Clinical significance
The IMA and/or its branches must be resected for a left hemicolectomy.{{Cite journal |last1=Charan|first1=Ishwar |last2=Kapoor|first2=Akhil|last3=Singhal|first3=Mukesh Kumar |last4=Jagawat|first4=Namrata|last5=Bhavsar|first5=Deepak|last6=Jain|first6=Vikas|last7=Kumar|first7=Vanita|last8=Kumar|first8=Harvindra Singh|date=December 2015|title=High Ligation of Inferior Mesenteric Artery in Left Colonic and Rectal Cancers: Lymph Node Yield and Survival Benefit |journal=The Indian Journal of Surgery |volume=77|issue=Suppl 3|pages=1103–1108|doi=10.1007/s12262-014-1179-2|issn=0972-2068|pmc=4775673|pmid=27011519 }}
A horseshoe kidney, a common (1 in 500) anomaly of the kidneys, will be positioned below the IMA.{{Cite journal|last1=Schiappacasse |first1=G|last2=Aguirre|first2=J|last3=Soffia|first3=P|last4=Silva|first4=C S|last5=Zilleruelo|first5=N|date=January 2015|title=CT findings of the main pathological conditions associated with horseshoe kidneys |journal=The British Journal of Radiology |volume=88 |issue=1045 |doi=10.1259/bjr.20140456|issn=0007-1285|pmc=4277381|pmid=25375751 }}{{Cite web|url=https://www.kenhub.com/en/library/anatomy/horseshoe-kidney-transplantation|title=Clinical case: Horseshoe kidney transplantation |website=Kenhub|access-date=2019-09-28}}
Additional images
File:Gray531.png|The abdominal aorta and its branches.
File:Gray537.png|The inferior mesenteric artery and its branches.
File:Gray847.png|Abdominal portion of the sympathetic trunk, with the celiac plexus and hypogastric plexus.
File:Gray1042.png|Duodenojejunal fossa.
File:Gray1121.png|Posterior abdominal wall, after removal of the peritoneum, showing kidneys, suprarenal capsules, and great vessels.
File:Gray1227.png|Front of abdomen, showing surface markings for arteries and inguinal canal.
File:Slide4nn.JPG|Inferior mesenteric artery
File:Slide2erer.JPG|Lumbar and sacral plexus. Deep dissection.Anterior view.
File:Slide1ewew.JPG|Lumbar and sacral plexus. Deep dissection.Anterior view.
File:Slide2ewew.JPG|Lumbar and sacral plexus. Deep dissection.Anterior view.
References
{{Reflist}}
External links
- [https://www.youtube.com/watch?v=4L8ANPCqosM Lotti M. Anatomy in relation to left colectomy]
- {{SUNYAnatomyFigs|39|02|05}} - "Branches of the inferior mesenteric artery."
- {{SUNYAnatomyLabs|40|11|01|03}} - "Posterior Abdominal Wall: Branches of the Abdominal Aorta"
- {{SUNYAnatomyImage|7|9|24}}
- {{SUNYAnatomyImage|7|9|97}}
- {{SUNYAnatomyImage|8|4|07}}
- {{SUNYAnatomyImage|8|6|59}}
- {{UMichAtlas|abdo_wall70}} - "Posterior Abdominal Wall, Dissection, Anterior View"
- {{NormanAnatomy|sup&infmesentericart}}
{{Arteries of thorax and abdomen}}
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