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Left colic artery

The left colic artery is the highest branch of the inferior mesenteric artery (IMA). It arises posterior to the peritoneum, usually opposite the left renal vein, and courses upward and to the left toward the descending colon and splenic flexure. Along its path, it passes anterior to the left kidney and posterior to the inferior mesenteric vein.

The artery typically divides into ascending and descending branches:

  • The ascending branch runs upward toward the splenic flexure and distal transverse colon, where it anastomoses with branches of the middle colic artery (superior mesenteric artery origin).

  • The descending branch runs inferiorly to supply the descending colon, forming an anastomosis with sigmoid arteries.

Through these arcades, the left colic artery contributes significantly to the marginal artery of Drummond, ensuring collateral circulation between the SMA and IMA territories. This vascular connection is critical in maintaining perfusion of the splenic flexure, a watershed area prone to ischemia.

Clinically, the left colic artery is important in left-sided colon resections, ischemic colitis, mesenteric ischemia, and interventional embolization procedures.

Synonyms

  • Arteria colica sinistra

  • Superior branch of inferior mesenteric artery

Function

  • Provides arterial blood supply to the descending colon and splenic flexure

  • Forms collaterals with the middle colic artery (SMA) and sigmoid arteries (IMA)

  • Contributes to the marginal artery of Drummond, maintaining redundancy of mesenteric blood flow

  • Key vessel in surgical anastomoses and ischemic disease of the colon

Branches

  • Ascending branch → splenic flexure, distal transverse colon (anastomosis with middle colic artery)

  • Descending branch → descending colon (anastomosis with sigmoid arteries)

MRI Appearance

T1-weighted images:

  • Appears as a flow void (black linear lumen) coursing in the left mesocolon

  • Surrounded by hyperintense fat planes, aiding identification

T2-weighted images:

  • Lumen seen as a signal void against intermediate bowel wall and fat

  • Edematous bowel wall (ischemia or colitis) enhances conspicuity of artery’s relation to colon

STIR:

  • Fat suppression highlights the artery’s course through mesocolon

  • Perivascular inflammatory changes appear bright hyperintense

T1 Fat-Saturated (Pre-contrast):

  • Lumen often appears intermediate signal intensity, standing out against suppressed mesenteric fat

  • Useful for distinguishing artery from adjacent fat planes

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Left colic artery enhances brightly and homogeneously

  • Defines arterial course, arcades, and collaterals with SMA and sigmoid arteries

  • Detects stenosis, occlusion, or neovascularization

MRA (Magnetic Resonance Angiography):

  • Excellent for mapping origin from IMA, course, and branching

  • Shows contribution to the marginal artery of Drummond

  • Useful in patients with suspected ischemia, pre-surgical planning, or vascular anomalies

CT Appearance

CT Pre-Contrast:

  • Appears as a tubular soft-tissue structure in mesocolon, difficult to differentiate without contrast

  • May show mural calcifications in atherosclerosis

CT Post-Contrast:

  • Enhances vividly along its mesenteric course

  • Helps identify relation to left kidney, colon, and inferior mesenteric vein

  • Detects active bleeding or vascular malformations

CT Angiography (CTA):

  • Gold standard for visualization of the left colic artery

  • High-resolution multiplanar and 3D reconstructions show origin, ascending and descending branches, and marginal artery arcades

  • Essential for diagnosing ischemic colitis, planning colectomy, or embolization

  • Identifies stenosis, occlusion, aneurysm, and collateral networks

CT images

Left colic artery CT axial anatomy image -img-00000-00000

CT images

Left colic artery CT axial anatomy image -img-00000-00000_00001

CT images

Left colic artery CT axial anatomy image -img-00000-00000_00002

MRI image

Left colic artery MRI coronal anatomy image -img-00000-00000