Revision 2 for 'Arc of Riolan'
Arc of Riolan
The arc of Riolan (Jean Riolan (b. 1580, d. 1657) French anatomist) is also known as the meandering mesenteric artery or central anastomotic mesenteric artery.
It is an inconstant artery that connects the proximal superior mesenteric artery (SMA) or one of its primary branches to the proximal inferior mesenteric artery (IMA) or one of its primary branches. It is classically described as connecting the middle colic branch of the SMA with the left colic branch of the IMA. It forms a short loop that runs close to the root of the mesentery.
When present, the AOR is an important connection between the SMA and IMA in the setting of arterial occlusion or significant stenosis. In proximal SMA occlusion, the AOR provides collateral flow from the IMA to the SMA territory. In proximal IMA occlusion, it provides collateral flow from the SMA to the IMA territory. In distal abdominal aortic occlusion it provides collateral flow from SMA to IMA to iliac vessels (via the superior rectal artery) and then to the lower limbs (via the external iliac artery).