The Superior and Inferior Mesenteric Arteries
About
The superior mesenteric artery (SMA) is a significant branch of the abdominal aorta. The single visceral branch emerges below the celiac trunk (at L1 vertebral level). It is essential for supplying blood to the midgut, which includes most of the small intestine and 2/3 of the transverse portion of the large intestine.
Anatomical Course
The superior mesenteric artery originates from the anterior surface of the abdominal aorta and descends, crossing over the left renal vein, in front of the uncinate process of the pancreas and the 3rd part of the duodenum (horizontal part), and continues along the root of the mesentery proper toward the ileocecal junction.
Branches
1. Inferior Pancreaticoduodenal Artery: The first branch of the SMA and branches into anterior and posterior branches. Supplies the head of the pancreas and the duodenum.
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- The anterior branch: anastomoses with the superior pancreaticoduodenal artery
- The posterior branch: anastomoses with the posterior branch of the superior pancreaticoduodenal artery.
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2. Jejunal and Ileal Arteries: Numerous branches from the left side of the SMA, form arcades, secondary arcades, and vasa recta. Supplies the jejunum and ileum of the small intestine.
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3. Middle Colic Artery: Runs within the transverse mesocolon to supply the transverse colon. It anastomoses with branches of the left colic artery which is a branch of the inferior mesenteric artery and right colic artery, the anastomoses are formed by marginal branches.
4. Right Colic Artery: Originates from the right side of the SMA, lower to the middle colic artery to supply the ascending colon and forms anastomoses with the middle colic artery (via ascending marginal branches) and ileocolic artery (via descending marginal branches).
5. Ileocolic Artery: Courses towards the ileocecal junction to supple the terminal ileum, appendix (via the appendicular artery), caecum, and the ascending colon.
- Branches:
1. Ileal branch
2. appendicular branch
3. Ascending branch
4. Anterior caecal branch
5. Posterior caecal branch
About
The inferior mesenteric artery (IMA) is the last single visceral branch of the abdominal aorta. It arises from the left side and functions to deliver blood to the hindgut, including the 1/3 of the transverse colon (distal), descending colon, sigmoid colon, and rectum. It originates from the abdominal aorta at the level of the L3 vertebra, just above the point where the aorta divides into the common iliac arteries.
Branches
​1. Left Colic Artery: The left colic artery ascends and moves laterally, dividing into ascending and descending branches.
- The ascending branch: anastomoses with the left branch of the middle colic artery. It supplies the 1/3 distal part of the transverse colon and the upper part of the descending colon (via the descending branch of the left colic artery).
2. Sigmoid Arteries: Supplies the sigmoid colon. Typically the first branch anastomoses with the descending branch of the left colic artery and the last branch anastomoses with the superior rectal artery.
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3. Superior Rectal Artery: The IMA continues to descend into the pelvis, and passes over the left common iliac artery to supply the rectum and the upper part of the anal canal. It forms anastomoses with the middle and inferior rectal arteries.