The puborectalis is the innermost component of the levator ani, forming a U-shaped sling around the anorectal junction. Its tonic contraction maintains the anorectal angle — the primary mechanical barrier to solid stool incontinence. It is unique in having no bony insertion, functioning purely as a dynamic sling.
| Origin | Pubic body — inner surface of the inferior pubic ramus |
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| Insertion | Joins with the contralateral puborectalis behind the anorectal junction forming a sling — no bony insertion |
| Nerve Supply | Inferior rectal nerve (S3, S4); Pudendal nerve |
| Blood Supply | Inferior rectal artery |
| Actions | Creates the anorectal angle (80-90 degrees) that maintains faecal continence; Relaxes during defaecation to straighten the anorectal junction; Contracts voluntarily during straining to maintain continence |
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Puborectalis hypertonia (anismus) produces obstructed defaecation where the muscle fails to relax during attempted defaecation. Biofeedback therapy trains conscious relaxation of the puborectalis. In pelvic floor repair for prolapse, the puborectalis is identified and plicated to restore posterior support. EMG of the puborectalis is performed transnally in anorectal manometry.
Palpable as the posterior anorectal sling on digital rectal examination — the distinct muscular ridge felt 4-5 cm from the anal verge posteriorly.
Failure of puborectalis relaxation during defaecation producing obstructed defaecation syndrome with straining and incomplete evacuation, confirmed by defaecation proctography and treated by biofeedback.
