Editing Large intestine (section)

===Blood supply===
[[Artery|Arterial]] supply to the colon comes from branches of the [[superior mesenteric artery]] (SMA) and [[inferior mesenteric artery]] (IMA). Flow between these two systems communicates via the [[marginal artery of the colon]] that runs parallel to the colon for its entire length. Historically, a structure variously identified as the arc of Riolan or meandering mesenteric artery (of Moskowitz) was thought to connect the [[Anatomical terms of location#Proximal and distal|proximal]] SMA to the proximal IMA. This variably present structure would be important if either vessel were occluded. However, at least one review of the literature questions the existence of this vessel, with some experts calling for the abolition of these terms from future medical literature.<ref>{{cite journal |last1=Lange |first1=Johan F. |last2=Komen |first2=Niels |last3=Akkerman |first3=Germaine |last4=Nout |first4=Erik |last5=Horstmanshoff |first5=Herman |last6=Schlesinger |first6=Frans |last7=Bonjer |first7=Jaap |last8=Kleinrensink |first8=Gerrit-Jan |title=Riolan's arch: confusing, misnomer, and obsolete. A literature survey of the connection(s) between the superior and inferior mesenteric arteries |journal=Am J Surg |date=June 2007 |volume=193 |issue=6 |pages=742–748 |doi=10.1016/j.amjsurg.2006.10.022|pmid=17512289 }}</ref>

[[Vein|Venous]] drainage usually mirrors colonic arterial supply, with the [[inferior mesenteric vein]] draining into the [[splenic vein]], and the [[superior mesenteric vein]] joining the splenic vein to form the [[hepatic portal vein]] that then enters the [[liver]]. [[Middle rectal veins]] are an exception, delivering blood to [[inferior vena cava]] and bypassing the liver.<ref>{{cite journal |last1=van Hoogdalem |first1=Edward |last2=de Boer |first2=Albertus G. |last3=Breimer |first3=Douwe D. |title=Pharmacokinetics of rectal drug administration, Part I. General considerations and clinical applications of centrally acting drugs |journal=Clinical Pharmacokinetics |date=July 1991 |volume=21 |issue=1 |page=14 |doi=10.2165/00003088-199121010-00002 |pmid=1717195 |url=https://pubmed.ncbi.nlm.nih.gov/1717195/ |access-date=18 March 2024 |issn=0312-5963 |quote=The superior rectal vein, perfusing the upper part of the rectum, drains into the portal vein and subsequently into the liver On the other hand, the middle and inferior rectal veins drain the lower part of the rectum and venous blood is returned to the inferior vena cava.}}</ref>