Superior Mesenteric Artery Origin
The superior mesenteric artery is a direct branch of the abdominal aorta. 1
Anatomical Origin and Location
The superior mesenteric artery (SMA) arises from the anterior (ventral) surface of the abdominal aorta, typically approximately 1 cm below the celiac trunk origin. 1, 2 This is the standard anatomical configuration described in major cardiovascular guidelines when discussing mesenteric vessel anatomy and pathology. 1
Specific Vertebral Level
- The SMA most commonly originates at the lower third of the first lumbar vertebra (L1) in approximately 77% of cases 3
- The origin can range from the lower third of T12 to the lower third of L1 3
- The average distance between the celiac trunk and SMA origin is 1.84 cm (range 0.6-1.5 cm in 85% of cases) 3
Relationship to Other Vessels
The SMA's position relative to other major abdominal vessels is clinically important:
- Celiac trunk: Located approximately 1-2 cm proximal (above) the SMA 2, 3
- Inferior mesenteric artery: Located approximately 6.67 cm distal (below) the SMA 3
- Aortic bifurcation: Located approximately 10.39 cm distal to the SMA origin 3
Clinical Relevance of Origin Location
Understanding the SMA's origin from the aorta is critical for several clinical scenarios:
Atherosclerotic Disease
The typical atherosclerotic lesions causing mesenteric ischemia are ostial plaques at the SMA origin from the aorta, which are actually protruding aortic plaques rather than intrinsic SMA disease. 1 This makes lateral aortography essential for visualizing these origin lesions. 1
Endovascular Procedures
During thoracoabdominal aortic endograft procedures, the SMA origin from the aorta may require intentional coverage to achieve distal seal, necessitating debranching procedures such as aorta-to-SMA bypass grafts. 1
Imaging Considerations
The ostial location of the SMA origin makes it well-suited for visualization by:
- Duplex ultrasound (85-90% sensitivity for proximal SMA stenosis) 4
- CT angiography (94-95% sensitivity and specificity) 1
- Lateral aortography for definitive visualization of origin lesions 1
Anatomical Variations
While the SMA typically arises independently from the aorta below the celiac trunk, several variations exist:
- Direct apposition to the celiac trunk occurs in 57.6% of cases (external distance 0 mm), though internal distance remains 10-30 mm 2
- Celiacomesenteric trunk (common origin with celiac trunk) is rare but reported 5, 6
- Origin from right hepatic artery is the most common variation (6.13%) 5
These variations are clinically significant for surgical planning and understanding collateral flow patterns in mesenteric ischemia. 7, 5