The rectococcygeus muscle is a paired smooth muscle band connecting the posterior rectal wall to the coccyx, part of the complex of muscles maintaining the anorectal position and angle. It runs in the retrorectal space and is an important landmark in posterior rectal dissection during abdominoperineal resection and low anterior resection. Its tonic contraction contributes to the maintenance of faecal continence by helping maintain the anorectal angle.
| Origin | Posterior rectal wall at the anorectal junction level, arising from the longitudinal muscle coat of the rectum |
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| Insertion | Anterior surface of the coccyx (2nd-4th coccygeal segments) and the anococcygeal raphe |
| Nerve Supply | Sympathetic fibres from the inferior hypogastric plexus; branches from S4 |
| Blood Supply | Middle rectal artery; median sacral artery |
| Actions | Maintains the anorectal angle by drawing the posterior anorectal wall toward the coccyx; acts as a posterior tether of the rectum preventing excessive anterior displacement; contributes to coccygeal and anorectal stability |
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The rectococcygeus is divided during posterior total mesorectal excision (TME) as the mesorectal envelope is sharply dissected from the presacral fascia — the muscle lies posterior to the mesorectum and must not be mistaken for the mesorectal fascia. Injury to the rectococcygeus during coccygectomy or posterior pelvic floor repair produces posterior anorectal displacement and contributes to post-operative defaecatory dysfunction. Coccydynia may involve the rectococcygeus muscle as a traction source on the coccyx, contributing to the pain of this condition.
Posterior TME for rectal carcinoma requires identification and sharp division of the rectococcygeus muscle fibres at the Waldeyer's fascia level as the posterior mesorectal plane is developed; blunt posterior dissection above this level risks tearing through the mesorectum rather than following the embryological plane.
