Arc of Riolan revisited - proposal of a new classification system

The arterial supply of the large colon is provided by the superior mesenteric artery (SMA) and inferior mesenteric artery (IMA). A particularly important area, especially in the field of colorectal surgery, is the splenic flexure of the colon. There is a noticeable misunderstanding in the correct nomenclature of the major arterial anastomoses between SMA and IMA - Drummond's Marginal Artery (DMA), Arc of Riolan (AOR), and Moskovitz Artery (MA). The aim of this study is to organise the nomenclature and propose a new simplified one to facilitate communication between physicians of various specialties.

Fourteen formalin-fixed cadavers (9 male, 5 female) accessible from the Chair of Anatomy of the Jagiellonian University Collegium Medicum were dissected to examine and describe the anatomical variations of anastomoses between SMA and IMA.

The artery of Drummond was present in all 14 specimens maintaining the continuity of the vessel along its entire course. The Arc of Riolan was found in 7 out of 14 cadavers (50%). The artery of Moskovitz was not found. The average length measured between IMA and aortic bifurcation and between IMA and SMA was 51.00 mm and 84.68 mm, respectively.

SMA and IMA anastomoses form an arterial network that is characterised by high variability and trail in surgically strategic areas. For this reason, simplifying the terminology and using unambiguous names of these vessels based on their trail and anatomical relationship with IMV are crucial for the proper planning and execution of surgical procedures performed on the colon.