The Arc of Riolan (AOR) and Meandering Moskowitz Artery (MMA) are well-known eponyms that refer to anas-
tomoses between the superior and inferior mesenteric arteries. Despite frequent use, their definitions vary in the
literature. Preservation of these collaterals is crucial for maintaining colonic blood supply and avoiding surgical
complications. Our study sought to clarify these definitions by examining their origins, evolution, and varying de-
scriptions. The RVU-MCOM library literature search tool and Google Scholar were used to access online databas-
es (MEDLINE Complete, DOAJ, ASI). Search terms included “Arc of Riolan,” “Riolan’s arch,” “Arcus Riolani,”
“Meandering artery of Moskowitz,” “Meandering Moskowitz artery,” and “Moskowitz artery” in different com-
binations. 55 full-text articles were included in our review, with no restrictions on publication date. Non-English
articles and those lacking relevant information on the MMA and AOR were excluded. The AOR was described as
a connection between the Middle Colic artery (MCA) and the Left Colic artery (LCA), with about 82% of authors
distinguishing it from the Marginal artery (MA). The MMA was more consistently defined as linking the proximal
MCA to the ascending LCA. Although descriptions became more detailed, the literature remains divided: some
authors consider the AOR, MMA, and MA distinct, while others view only the AOR or MMA as an additional
collateral to the MA. Limitations included access to historical works and language barriers that prevented use
of potentially relevant articles. The use of eponyms for these anastomoses remains problematic and ambiguous
within the literature, highlighting the need for a new naming convention free of eponyms.
