Fig. 7
From: MRI of rectal cancer—relevant anatomy and staging key points
The rectum’s arterial supply has 3 to 4 routes. The main route is the superior rectal artery (arrow in a). The middle rectal arteries are inconsistent but may be present in up to 57% of cases. In b, a large calibre right middle rectal artery (arrow) arising from the internal iliac artery pierces the mesorectal fascia at its anterolateral aspect. The inferior rectal arteries originate from the internal pudendal arteries, are usually small in caliber and cross the ischioanal fossae towards the anal canal (arrows in c). The middle sacral artery courses down along the lumbosacral vertebrae, within the presacral space (arrow in d)