Inferior mesenteric artery
Encyclopedia
In human anatomy
, the inferior mesenteric artery, often abbreviated as IMA, supplies the large intestine
from the left colic (or splenic) flexure
to the upper part of the rectum
, which includes the descending colon
, the sigmoid colon
, and part of the rectum. 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). The territory of distribution of the IMA is more or less equivalent to the embryonic hindgut
.
below the renal artery
branch points, and approximately midway between these and the aortic bifurcation
(into the common iliac arteries), L3 vertebral level.
The IMA has the following branches:
All these arterial branches further divide into arcades
which then supply the colon
at regular intervals.
, the inferior mesenteric vein
, which drains into the splenic vein
.
The IMV therefore drains to the portal vein and does not fully mirror the course of the IMA.
A horseshoe kidney
, a common (1 in 600) anomaly of the kidneys, will be positioned below the IMA.
Human anatomy
Human anatomy is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross anatomy is the study of anatomical structures that can be seen by the naked eye...
, the inferior mesenteric artery, often abbreviated as IMA, supplies the large intestine
Large intestine
The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
from the left colic (or splenic) flexure
Splenic flexure
The splenic flexure is a sharp bend between the transverse and the descending colon in the left upper quadrant of humans. The left colic flexure is near the spleen, and hence called the splenic flexure. There are two colic flexures in the transverse colon — the other being the hepatic...
to the upper part of the rectum
Rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
, which includes the descending colon
Descending colon
The descending colon of humans passes downward through the left hypochondrium and lumbar regions, along the lateral border of the left kidney....
, the sigmoid colon
Sigmoid colon
The sigmoid colon is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 40 cm...
, and part of the rectum. Proximally, its territory of distribution overlaps (forms a watershed) with the middle colic artery
Middle colic artery
The middle colic artery is a branch of the superior mesenteric artery that mostly supplies the transverse colon. It arises just below the pancreas, and, passing downward and forward between the layers of the transverse mesocolon, divides into two branches: right and left.* The right branch...
, and therefore the superior mesenteric artery. The SMA and IMA anastomose via the marginal artery of the colon
Marginal artery of the colon
In human anatomy, the marginal artery of the colon, also known as the marginal artery of Drummond and artery of Drummond , is a blood vessel that anastomoses the inferior mesenteric artery with the superior mesenteric artery...
(artery of Drummond). The territory of distribution of the IMA is more or less equivalent to the embryonic hindgut
Hindgut
The hindgut is the posterior part of the alimentary canal. In mammals, it includes the distal third of the transverse colon and the splenic flexure, the descending colon, sigmoid colon and rectum.-Blood flow:...
.
Branching
The IMA branches off the anterior surface of the abdominal aortaAbdominal aorta
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 .-Path:...
below the renal artery
Renal artery
The renal arteries normally arise off the side of the abdominal aorta, immediately below the superior mesenteric artery, and supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle with the aorta....
branch points, and approximately midway between these and the aortic bifurcation
Aortic bifurcation
The aortic bifurcation is the point at which the abdominal aorta bifurcates into the left and right common iliac arteries. The aortic bifurcation occurs at the level of the fourth lumbar vertebrae....
(into the common iliac arteries), L3 vertebral level.
The IMA has the following branches:
| Branch | notes >- | left colic artery Left colic artery The left colic artery is a branch of the inferior mesenteric artery that runs to the left behind the peritoneum and in front of the psoas major muscle, and after a short, but variable, course divides into an ascending and a descending branch; the stem of the artery or its branches cross the left... |
descending colon Descending colon The descending colon of humans passes downward through the left hypochondrium and lumbar regions, along the lateral border of the left kidney.... >- | sigmoid branches Sigmoid arteries The sigmoid arteries, two or three in number, run obliquely downward and to the left behind the peritoneum and in front of the Psoas major, ureter, and internal spermatic vessels.... |
>- | effectively the terminal branch of the IMA (the continuation of the IMA after all other branches) |
All these arterial branches further divide into arcades
Arterial arcades
Arterial arcades are loops of arteries around the jejunum and ileum.Nearest the duodenum the mesenteric loops are primary, the vasa recta are long and regular in distribution, and the translucent spaces are extensive....
which then supply the colon
Colon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
at regular intervals.
Associated veins
The IMA is accompanied along its course by a similarly named veinVein
In the circulatory system, veins are blood vessels 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 blood to the heart...
, the inferior mesenteric vein
Inferior mesenteric vein
In human anatomy, the inferior mesenteric vein 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...
, which drains into the splenic vein
Splenic vein
In anatomy, the splenic vein is the blood vessel that drains blood from the spleen.It joins with the superior mesenteric vein, to form the hepatic portal vein and follows a course superior to the pancreas, alongside of the similarly named artery, the splenic artery.It collects branches from the...
.
The IMV therefore drains to the portal vein and does not fully mirror the course of the IMA.
Surgery and pathology
The IMA and/or its branches must be resected for a left hemicolectomy.A horseshoe kidney
Horseshoe kidney
Horseshoe kidney, also known as renal fusion or super kidney, is a congenital disorder affecting about 1 in 400 people. In this disorder, the patient's kidneys fuse together to form a horseshoe-shape during development in the womb...
, a common (1 in 600) anomaly of the kidneys, will be positioned below the IMA.