Intermediate Lateral Flexure of the Male Rectum, Lateral View

Description

Seen in lateral profile, the adult male rectum follows the anterior concavity of the sacrum and coccyx, forming the intermediate lateral flexure (flexura lateralis recti), often described in classical terms as the sacral flexure (flexura sacralis recti). Superiorly, the rectum transitions toward the rectosigmoid junction, while inferiorly it continues to the anal canal as it approaches the pelvic floor. The depicted curvature is positioned posterior to the urinary bladder and prostate and anterior to the presacral fascia, with the curve deflecting to one side (right lateral in typical catalog tagging) along its mid-rectal segment. Small changes in this contour alter the relationship to the sacral promontory and the mesorectum. For colorectal and pelvic surgeons, the intermediate flexure is not a trivia point, it is the bend that drives instrument angulation and endoscopic torque as the scope passes from rectosigmoid into the mid-rectum. In total mesorectal excision, understanding how the rectal wall and mesorectum track along the sacrum helps avoid drifting posteriorly into the presacral venous plexus or too anteriorly toward Denonvilliers fascia, where the prostate and seminal vesicles sit close. A common problem in teaching is that learners picture the rectum as straight. It is not. Use this artwork in anatomy and proctology lectures to anchor discussion of rectal curvatures, the rectosigmoid transition, and how lateral bends influence flexible sigmoidoscopy and colonoscopy technique. It also suits operative atlases describing low anterior resection, transanal TME orientation, and pelvic MRI correlation for rectal cancer staging. Anatomical accuracy verified by SciePro's Medical Advisory Board.