Anterior collateral pathway (also known as Winslow`s pathway) is a collateral circulation from the subclavian artery via the internal mammary artery, the superior epigastric artery, and the inferior epigastric artery into the external iliac artery. The present case only studied the abdome and lower limbs, not contemplating the thoracic vessels. 

A study demonstrated that in 95% of patients with aortoiliac occlusion, this pathway was functioning as a important collateral route providing lower-extremity perfusion.

On this case there is also a communication between the proximal superior mesenteric artery (SMA) and the proximal inferior mesenteric artery (IMA) - Arc of Riolan. Note that the origin of IMA is occluded and this anastomosis ensure the arterial flow to it.