Investigation of the Clinical Significance of the Arc of Riolan: A Review

All the blood of the small intestine comes from the truncus coeliacus and arteria (a.) mesenterica superior. Vascular anatomy may differ between people. Arc of Riolan, first described by Jean Riolan (1580-1657), a French anatomist, is an anastomotic vascular structure between the a. colica media branch of the a. mesenterica superior and the a. colica sinistra branch of the a. mesenterica inferior. It mainly provides collateral perfusion and blood supply after a. mesenterica superior or a. mesenterica inferior occlusion and atherosclerotic stenosis. In the event of occlusion of both the a. mesenterica superior and truncus coeliacus, flow to these arteries may be via the a. mesenterica inferior. The main pathologies in which the clinical importance of the arc of Riolan is observed are obstruction or stenosis of the a. mesenterica superior, obstruction or stenosis of the arteria mesenterica inferior, colorectal cancer (colon cancer) and active ulcerative colitis. Many studies have shown that these vascular structures and the arc of Riolan, which existed before these pathologies, can expand. Because of this development of collateral circulation, many patients may be asymptomatic despite severe stenosis or complete obstruction of at least two of the three main splanic arteries. In this review the circulatory anatomy of the intestine, the factors affecting normal circulation and the resulting diseases are described in the current literature. In this context, studies emphasising the importance of the arc of Riolan were reviewed and clinicians were aimed to have more information about the presence of the arc of Riolan.