Topics

Topic

design image
Superior mesenteric artery (SMA)

The superior mesenteric artery (SMA) is a major unpaired branch of the abdominal aorta, arising at the level of L1 vertebra, just below the celiac trunk. It supplies the midgut structures, including the distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal two-thirds of the transverse colon.

The SMA emerges anteriorly from the aorta, running inferiorly and anterior to the left renal vein, crossing over the third part of the duodenum, and entering the mesentery where it travels between the layers of the mesentery to reach the ileum. Its close relation to the duodenum gives rise to the clinical entity superior mesenteric artery syndrome (Wilkie’s syndrome), where compression of the duodenum causes obstruction.

The SMA provides several important branches: the inferior pancreaticoduodenal artery, jejunal and ileal arteries (forming arterial arcades and vasa recta), ileocolic artery, right colic artery, and middle colic artery. These branches ensure a rich collateral blood supply, linking with the celiac trunk above and the inferior mesenteric artery below via arcades and marginal artery of Drummond.

Synonyms

  • SMA

  • Arteria mesenterica superior

  • Midgut artery

Function

  • Provides arterial blood to midgut-derived structures: distal duodenum → proximal 2/3 of transverse colon

  • Contributes to collateral circulation via arcades with celiac trunk and inferior mesenteric artery

  • Maintains adequate intestinal perfusion for digestion, absorption, and gut motility

  • Landmark in imaging and surgery for mesenteric ischemia, bowel obstruction, and abdominal trauma

Branches

  • Inferior pancreaticoduodenal artery

  • Jejunal arteries

  • Ileal arteries

  • Ileocolic artery

  • Right colic artery

  • Middle colic artery

MRI Appearance

T1-weighted images:

  • SMA appears as a flow void (black lumen) in mesenteric root

  • Surrounded by bright mesenteric fat, which aids identification

T2-weighted images:

  • Lumen seen as a signal void; mural thickening or thrombosis alters signal intensity

  • Hyperintense mesenteric edema may highlight SMA course in ischemia

STIR:

  • Suppresses fat, making SMA wall and perivascular pathology more conspicuous

  • Detects perivascular edema, inflammation, or lymphadenopathy

T1 Fat-Saturated (Pre-contrast):

  • Lumen shows intermediate signal standing out against suppressed fat

  • Aids in visualizing vessel before contrast

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • SMA enhances brightly and homogeneously

  • Filling defects indicate stenosis, thrombus, or dissection

  • Visualizes small branches and arcades in mesentery

MRA (Magnetic Resonance Angiography):

  • Provides detailed 3D reconstruction of SMA origin, course, and branches

  • Detects stenosis, occlusion, aneurysm, and collateral pathways

  • Essential for evaluating mesenteric ischemia non-invasively

CT Appearance

CT Pre-Contrast:

  • SMA visible as a round or tubular soft-tissue density anterior to the aorta

  • Calcified atherosclerotic plaques may be detected in vessel wall

CT Post-Contrast:

  • SMA enhances brightly, showing clear lumen and branching

  • Detects stenosis, dissection flaps, mural thickening, or thrombus

  • Perivascular fat stranding indicates inflammation

CT Angiography (CTA):

  • Gold standard for non-invasive SMA imaging

  • Shows SMA origin, length, branching pattern, and anastomoses with IMA and celiac trunk

  • Multiplanar and 3D reconstructions demonstrate stenosis, occlusion, aneurysm, mesenteric ischemia, and collateral flow

  • Critical in acute mesenteric ischemia, pre-surgical mapping, and trauma evaluation

MRI images

Superior mesenteric artery (SMA) coronal MRI anatomy image -img-00000-00000

CT images

Superior mesenteric artery (SMA) AXIAL CT anatomy image -img-00000-00000

CT images

Superior mesenteric artery (SMA) coronal CT anatomy image

CT images

Superior mesenteric artery (SMA) CT SAG IMAGE