The Arc of Riolan (AOR) and Meandering Moskowitz Artery (MMA) are variant anastomoses between the superior and inferior mesenteric arteries that provide collateral circulation to the colon when normal blood flow is impaired. Preservation of these anastomoses during surgery reduces postoperative compli- cations and improves patient outcomes. However, the use of eponyms to describe these arteries has led to confusion in the literature, highlighting the need for updated clinical data. The aim of our study was to investigate the prevalence of the AOR and MMA and provide data on the arteries connecting them: the middle colic artery (MCA) and left colic artery (LCA). 24 formalin-embalmed cadavers from the Colorado Anatomical Gift Program were obtained, and abdominal dissections were performed using the RVUANATOMY online dissector. 21 cadavers with intact MCA and LCA branches were included, while 3 were excluded due to arterial damage or large intestine pathology. The diameter of the vessels at their origin and the length to bifurcation was measured using a sliding vernier caliper (accurate to 1 mm). The AOR was present in 9.5% of cases, and the MMA was observed in 14.28%. The average diameters of the MCA and LCA were 3.58 mm and 4.28 mm, respectively, with average lengths of 3.09 cm and 5.77 cm. While the prevalence aligned with prior reports, significant variation in branching patterns was observed. Limitations include small sample size and potential dissection errors. Further research using angiography in larger populations is necessary to improve understanding of these anastomoses.
