Anatomical Form of the Male Sigmoid Colon Section

Description

Curving in the left lower quadrant, the distal descending colon transitions into the sigmoid colon (colon sigmoideum) as it leaves the splenic flexure and drifts inferiorly toward the pelvic brim. A posterior perspective places the sigmoid loop anterior to the left psoas major and iliacus, with the left ureter and gonadal vessels running retroperitoneally along the posterior abdominal wall, medial to the descending colon. The sigmoid mesocolon fans from the bowel to its posterior attachment, creating the peritoneal reflection that separates intraperitoneal sigmoid colon from the retroperitoneal fascia overlying the kidney, quadratus lumborum, and iliac vessels. Superiorly, the splenic flexure sits inferior to the spleen and adjacent to the tail of the pancreas, tethered by peritoneal folds that define its limited mobility compared with the sigmoid. Posterior anatomy of the splenic flexure and sigmoid is a frequent site of avoidable injury. Mobilization during a left colectomy or sigmoidectomy requires controlled division of the lateral peritoneal attachments (line of Toldt) while keeping the dissection plane on the mesocolic fascia to protect the left ureter and preserve the gonadal vessels. It also clarifies why pathology at the splenic flexure, including ischemic colitis in the watershed region of Griffiths’ point near the marginal artery, can present differently from diverticular disease, which clusters in the sigmoid where intraluminal pressure is highest. Use this artwork in surgical teaching on medial-to-lateral versus lateral-to-medial mobilization, in anatomy courses covering peritoneal compartments and mesenteries, or in clinical publications discussing diverticulitis, volvulus, or ureteric risk during pelvic and left-sided colorectal procedures. A solid operative roadmap. Anatomical accuracy verified by SciePro's Medical Advisory Board.