The Blood Vessels of the Rectum of a Human Male Viewed Laterally

Description

Oriented in a lateral view of the male pelvis, the rectum is shown continuous superiorly with the sigmoid colon and terminating inferiorly at the anal canal, with the mesorectal envelope carrying accompanying vessels and nodal tissue. Arterial supply is represented by the superior rectal artery descending from the inferior mesenteric artery along the posterior and lateral rectal wall, with middle rectal branches entering from the lateral pelvic wall near the internal iliac system. Inferior rectal arteries approach the distal rectum and anal canal from the internal pudendal artery, coursing medially through the ischioanal fossa. Venous drainage parallels this arrangement, with the superior rectal vein ascending toward the inferior mesenteric vein and portal circulation, while middle and inferior rectal veins drain laterally into the internal iliac veins and systemic circuit. A lateral perspective clarifies the portosystemic anastomosis at the rectum, where submucosal channels link superior rectal (portal) and middle and inferior rectal (systemic) tributaries. This is the substrate for internal hemorrhoids and for anorectal varices in portal hypertension, a distinction that matters endoscopically and in operative planning because bleeding behavior and recurrence risk differ. The same vascular map guides total mesorectal excision and low anterior resection, where high ligation near the inferior mesenteric pedicle and careful preservation of lateral pelvic structures influence both perfusion and pelvic autonomic nerve safety. Bleeding can be brisk. Use this illustration in colorectal surgery texts, GI anatomy and physiology coursework, and radiology teaching files when correlating endoscopy, CT angiography, or pelvic MRI with the superior rectal and internal iliac vascular territories. It also suits patient education materials explaining hemorrhoids versus portal hypertensive anorectal varices and why treatment pathways diverge. Anatomical accuracy verified by SciePro's Medical Advisory Board.