The origins of historical terms, such as "Arc of Riolan" and "marginal artery of Drummond" are traced herein with emphasis on the inherent confusion caused when these terms are used. Basic mesenteric anatomy is briefly mentioned and pathologic anatomy with its altered direction of blood flow induced by atherosclerosis is stressed. The significance of the meandering mesenteric artery as the main collateral vessel between the superior and inferior mesenteric artery is emphasized along with preoperative and intraoperative ways to ascertain whether or not the origin of this latter vessel can be safely ligated. Specific operations, such as abdominal aortic aneurysmorrhaphy and sigmoid colectomy, which can potentially interfere with blood flow in the meandering mesenteric artery, are discussed in an attempt to prevent postoperative necrosis of any portion of the intestine that may have deficient mesenteric blood flow.