human anatomy The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a he ...

, the inferior mesenteric artery, often abbreviated as IMA, is the third main branch of the

abdominal aorta In human anatomy, the abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta (of the thorax). Structure The abdominal aorta begins at the level of the thoracic d ...

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 digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before being r ...

from the distal transverse colon to the upper part of the anal canal. 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 descendin ...

, the

sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...

, and part of the rectum.

Structure

Proximally, its territory of distribution overlaps (forms a watershed) with the

middle colic artery The middle colic artery is an artery of the abdomen; a branch of the superior mesenteric artery distributed to parts of the ascending and transverse colon. It usually divides into two terminal branches - a left one and a right one - which go on ...

, and therefore the

superior mesenteric artery In human anatomy, the superior mesenteric artery (SMA) is an artery which arises from the anterior surface of the abdominal aorta, just inferior to the origin of the celiac trunk, and supplies blood to the intestine from the lower part of the ...

. The SMA and IMA anastomose via the

marginal artery of the colon In human anatomy, the marginal artery of the colon, also known as the marginal artery of Drummond, the artery of Drummond, and simply as the marginal artery, is an artery that connects the inferior mesenteric artery with the superior mesenteric ar ...

(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 The hindgut (or epigaster) is the posterior ( caudal) part of the alimentary canal. In mammals, it includes the distal one third of the transverse colon and the splenic flexure, the descending colon, sigmoid colon and up to the ano-rectal juncti ...

Branches

The IMA branches off the anterior surface of the

below the

renal artery The renal arteries are paired arteries that supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle. The renal arteries carry a large portion of total blood flow to the kidneys. Up to a ...

branch points, 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 i ...

(into the common iliac arteries) at the L3 vertebral level. 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.

Associated veins

The IMA is accompanied along its course by a similarly named

vein Veins are blood vessels in 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 the pulmonary and umbilical veins, both of which carry oxygenated b ...

, 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 The spleen is an organ (biology), organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

. The IMV therefore drains to the portal vein and does not fully mirror the course of the IMA.

Clinical significance

The IMA and/or its branches must be resected for a left hemicolectomy. A

horseshoe kidney Horseshoe kidney, also known as ''ren arcuatus'' (in Latin), renal fusion or super kidney, is a congenital disorder affecting about 1 in 500 people that is more common in men, often asymptomatic, and usually diagnosed incidentally. In this disorder ...

, 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