Mesenteric vasculature and collateral pathways.

The arterial and venous circulation of the bowel is complex and is characterized by marked redundancy of multiple interconnecting branches, which provides a rich blood supply to aid in the digestive process and also serves to protect the bowel from potential ischemia or infarction. As a result of this circulatory pattern, anatomic variants and extensive collateral pathways are common. A thorough knowledge of both the arterial and venous mesenteric circulation, including normal, variant, and collateral anatomy, is necessary for the appropriate evaluation and management of the various disease processes that may affect the vascular supply of the gastrointestinal system.