经过多年观察研究发现，肠系膜下动脉（IMA）高位结扎为乙状结肠和直肠癌根治手术常规方法之一（在几个方面有一定优势），过去由于研究方法限制，对于IMA高位结扎后降乙结肠侧支血流通路只有“边缘弓”和“Riolan弓”理论（尤其术后Riolan弓的具体形态几乎没有直观显示的研究报道）。本人近5年潜心研究小血管的电子计算机断层扫描血管造影（CTA）成像方法，发现“Riolan弓”（加“”代表仍借用这一概念）的演变过程，并且引入流体力学原理进行解释，后通过术前、术后对照研究进行了验证。本文结合文献为大家疏理这方面研究思路，供大家参考。希望有更多医生加入进一步深入研究，并对大家手术具体操作的注意事项提供理论依据。

After years of comparative studies, high ligature of the inferior mesenteric artery (IMA) remains one of the routine methods in radical surgery for sigmoid and rectal cancer, offering certain advantages in several aspects. However, the collateral blood flow pathway of descengding and sigmoid colon after high ligature, in the past, has been limited to theoretical concepts such as the marginal artery and the Riolan arch (with scarce visual research reports on the specific morphology of the postoperative Riolan arch). In the past five years, we have dedicated ourselves to researching the computerized tomography angiography (CTA)imaging method of small blood vessels and have discovered the evolutionary process of the "Riolan arch" (indicated by quotation marks to borrow this concept). Furthermore, we have introduced principles of fluid dynamics to provide an explanation. Subsequently, the findings were validated through preoperative and postoperative comparative studies. This paper combines existing literature to elucidate research perspectives in this area, serving as a reference for further studies. It is hoped that more individuals will engage in deeper research and this work will contribute to the understanding attention point of specific operative procedures.