Vascular anatomy of the splenic flexure, focusing on the accessory middle colic artery and vein

The branching of the inferior mesenteric artery and vein varies among individuals. Three-dimensional CT angiography is a less invasive modality than traditional angiographic examination to assess the artery and vein.

There are 2 interpretations of Riolan's arch: (1) Riolan's arch is identical to a central part of the marginal artery (MA), connecting the superior (SMA) and the inferior mesenteric (IMA) arteries; and (2) Riolan's arch represents a rare artery, connecting the SMA and the IMA. The current review aims to emphasize the clinical importance of the colon's vasculature and to show the feasibility of abolishing the terms "Riolan's arch" and "meandering mesenteric artery." A literature survey was performed. It appears that no distinct identity can be ascribed to Riolan's arch and that the "meandering mesenteric artery" represents an angiographically hypertrophied MA and/or the ascending branch of the left colic artery. However, a rare, centrally located, communicating artery has been described. Generally, the MA is sufficient for left colic circulation after ligation of the IMA, but at the splenic flexure, patency of the ascending branch of the left colic artery can be primordial. As connections between the SMA and the IMA can be adequately described using structures mentioned in Terminologica Anatomica, the terms "Riolan's arch" and "meandering mesenteric artery" should be abolished.