The middle rectal artery is an artery in the pelvis that supplies blood to the rectum.Sigmoid colon and rectum, showing distribution of branches of inferior mesenteric artery and their anastomoses.Middle rectal artery The middle rectal artery is an artery in the pelvis that supplies blood to the rectum. The middle rectal artery usually arises with the inferior vesical artery, a branch of the internal iliac artery. It is distributed to the rectum, anastomosing with the inferior vesical artery, superior rectal artery, and inferior rectal artery. In males, the middle rectal artery may give off branches to the prostate and the seminal vesicles, while in females it gives off branches to the vagina.