The levator ani muscle has three parts. Which part forms a sling around the anorectal junction (anorectal ring) and is the most important component for maintaining faecal continence?
- A Iliococcygeus
- B Puborectalis ✓
- C Coccygeus
- D Pubococcygeus
Correct answer: B. Puborectalis
Explanation
Puborectalis arises from the pubic bone and forms a U-shaped sling around the posterior aspect of the anorectal junction, maintaining the anorectal angle (approximately 90° at rest). This anorectal angle is the most important mechanism in maintaining gross faecal continence. During defaecation, puborectalis relaxes, straightening the anorectal angle (to ~135°) to allow passage of stool. Disruption of puborectalis (in obstetric trauma, lateral internal sphincterotomy extending too far posteriorly) causes major faecal incontinence.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.