The Superior Mesenteric Artery (SMA)
The SMA is the primary blood supply to the midgut, originating from the abdominal aorta at the L1 vertebral level, just inferior to the celiac trunk.
Primary Branches
| Branch | Area Supplied |
|---|---|
| Inferior Pancreaticoduodenal | Head of pancreas and distal duodenum. |
| Jejunal and Ileal Arteries | Small intestine (jejunum and ileum). |
| Ileocolic, Right & Middle Colic | Cecum, ascending colon, and proximal 2/3 of the transverse colon. |
Clinical Significance
- SMA Syndrome: Occurs when the third part of the duodenum is compressed between the SMA and the abdominal aorta, often due to significant weight loss and loss of mesenteric fat.
- Collateralization: The SMA forms critical anastomoses with the celiac trunk (via pancreaticoduodenal arteries) and the inferior mesenteric artery (via the marginal artery of Drummond).
High-Yield Exam Pearl:
The SMA crosses anterior to the left renal vein. An abdominal aortic aneurysm or a tight SMA can potentially compress the renal vein, leading to left-sided varicocele or hematuria.