Arteries - Superior & Inferior Mesenteric
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Mesenteric arteries
- Both the superior and inferior arteries arise from the abdominal aorta and travel through the mesentery to deliver blood to organs of the digestive tract.
Superior mesenteric artery
- Supplies the pancreas, segments of the small intestine, and the proximal segments of the large intestine
- Gives rise to the:
- Inferior pancreaticoduodenal a.
- Middle colic a.
- Right colic a.
- Ileocolic a.
- The intestinal arteries (which supply the jejunum and ileum).
Inferior mesenteric artery
- Supplies the distal segments of the large intestine.
- Gives rise to the:
- Left colic a.
- Multiple sigmoid aa.
- Superior rectal a.
Marginal artery
- Forms from anastomoses of the superior and inferior mesenteric arteries.
Clinical correlations:
- The marginal artery provides an alternative blood pathway for the distal portion of the large intestine if the inferior mesenteric artery is infarcted.
- However, if the superior mesenteric artery is infarcted, necrosis of the small and large intestine results.
- Mesenteric arterial networks are highly variable; for example, it is not uncommon for the right or middle colic arteries to be absent.
- "Watershed regions" where the colon receives dual blood supply:
- Both the SMA and the IMA supply blood to the splenic flexure.
- Both the final sigmoidal artery branch and the superior rectal artery supply the rectosigmoid junction.
- These regions are vulnerable in colonic ischemia.
- Nutcracker Syndrome occurs when the left renal vein is compressed by the superior mesenteric artery and the aorta; patients experience flank pain, elevated renal vein pressure, and hematuria.
- Superior mesenteric artery syndrome occurs when the Superior mesenteric artery and aorta compress & obstruct the transverse portion of the duodenum; patients experience postprandial pain. It is most likely to occur in patients with weight loss, but not always.