human anatomy Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross ...

, 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 The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the Digestion, digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces befor ...

from the distal

transverse colon In human anatomy, the transverse colon is the longest and most movable part of the Large intestine#Structure, colon. Anatomical position It crosses the abdomen from the ascending colon at the right colic flexure (hepatic flexure) with a downward ...

to the upper part of the

anal canal The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional s ...

. The regions supplied by the IMA are the

descending colon In the anatomy of humans and homologous primates, the descending colon is the part of the colon extending from the left colic flexure to the level of the iliac crest (whereupon it transitions into the sigmoid colon). The function of the descen ...

, the sigmoid colon, and part of the

rectum The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces temporarily. The adult ...

Structure

Origin

The IMA arises from the anterior aspect of the abdominal aorta. Its origin is situated at the L3 vertebral level ( subcostal plane), below the origins of the two renal arteries, 3-4 cm above the

aortic bifurcation The aortic bifurcation is the point at which the abdominal aorta bifurcates (forks) into the left and right common iliac arteries. The aortic bifurcation is usually seen at the level of L4, just above the junction of the left and right common ...

, at the level of the umbilicus, and posterior to the inferior border of the horizontal (III) part of the

duodenum The duodenum is the first section of the small intestine in most vertebrates, including mammals, reptiles, and birds. In mammals, it may be the principal site for iron absorption. The duodenum precedes the jejunum and ileum and is the shortest p ...

Branches

Along its course, the IMA has the following 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 Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

, the

inferior mesenteric vein In human anatomy, the inferior mesenteric vein (IMV) is a blood vessel that drains blood from the large intestine. It usually terminates when reaching the splenic vein, which goes on to form the portal vein with the superior mesenteric vein (SMV) ...

, which drains into the

splenic vein In human anatomy, the splenic vein (formerly the lienal vein) is a blood vessel that drains blood from the spleen, the stomach fundus and part of the pancreas. It is part of the hepatic portal system. Structure The splenic vein is formed from ...

. The IMV drains to the

portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approxima ...

and does therefore not fully mirror the course of the IMA.

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. A horseshoe kidney, a common (1 in 500) anomaly of the kidneys, will be positioned below the IMA.

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

External links

Lotti M. Anatomy in relation to left colectomy
* - "Branches of the inferior mesenteric artery." * - "Posterior Abdominal Wall: Branches of the Abdominal Aorta" * * * * * - "Posterior Abdominal Wall, Dissection, Anterior View" * {{Authority control Arteries of the abdomen