Collateral Pathways from the Aorta to the Lower Extremities

Collateral pathways exist for arterial blood to reach the lower extremities when the infrarenal aorta is occluded.

• Anterior (Winslow) pathway: subclavian arteries to internal mammary arteries. Internal mammary arteries to superior epigastric arteries. Superior epigastric arteries to the inferior epigastric arteries. Inferior epigastric arteries to the external iliac arteries.
• Middle (visceral) pathway: Superior mesenteric artery to inferior mesenteric artery via the marginal artery of Drummond (marginal artery of the colon) and the arcade of Riolan (intestinal arterial arcade). Inferior mesenteric artery to superior hemorrhoidal artery. Superior hemorrhoidal artery to middle and inferior hemorrhoidal arteries. Middle and inferior hemorrhoidal arteries to the external iliac arteries.
• Posterior pathway (1): Intercostal, subcostal, and lumbar arteries to the superior gluteal and iliolumbar arteries. Superior gluteal and iliolumbar arteries to the internal iliac arteries. Internal iliac arteries to the external iliac arteries.
• Posterior pathway (2): Intercostal, subcostal, and lumbar arteries to the superficial and deep iliac circumflex arteries. Circumflex arteries to the external iliac arteries.

References

• Prager RJ, Akin JR, Akin GC, Binder RJ. Winslow's pathway: a rare collateral channel in infrarenal aortic occlusion. AJR Am J Roentgenol. 1977 Mar;128(3):485-7.
• Sebastià C, Quiroga S, Boyé R, Perez-Lafuente M, Castellà E, Alvarez-Castells A. Aortic stenosis: spectrum of diseases depicted at multisection CT. Radiographics. 2003 Oct;23 Spec No:S79-91.