The levator ani is divided into three functional components: puborectalis (the most medial sling-like portion around the anorectum providing continence), pubococcygeus (the middle portion with urethral and vaginal compression functions), and iliococcygeus (the lateral hammock portion forming the pelvic floor). Each subdivision has distinct clinical relevance in pelvic floor dysfunction.
| Origin | Pubococcygeus: posterior pubis and obturator fascia; Puborectalis: pubic body lateral to symphysis; Iliococcygeus: obturator internus fascia (arcus tendineus) and ischial spine |
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| Insertion | Pubococcygeus: anococcygeal raphe and coccyx; Puborectalis: joins contralateral muscle behind anorectal junction forming U-shaped sling; Iliococcygeus: anococcygeal raphe and coccyx |
| Nerve Supply | Levator ani nerve (S3-S4 direct branches from sacral plexus); inferior rectal branch of pudendal nerve |
| Blood Supply | Inferior gluteal artery; inferior vesical artery; internal pudendal artery |
| Actions | Pubococcygeus: elevates pelvic viscera and compresses the urethra, vagina, and anorectal canal; Puborectalis: maintains the anorectal angle (80-100 degrees at rest) critical for faecal continence; Iliococcygeus: forms the pelvic floor hammock supporting visceral load |
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Pelvic floor rehabilitation targets each subdivision selectively: puborectalis strengthening improves faecal continence, pubococcygeus exercises improve urinary continence and sexual function, iliococcygeus activation reduces pelvic organ prolapse. MRI dynamic defaecography images puborectalis function and anorectal angle. Levator ani avulsion (from the pubic bone during vaginal delivery) is detected by 3D perineal ultrasound and causes pelvic organ prolapse. Laparoscopic sacrocolpopexy for vault prolapse must account for levator ani anatomy.
Puborectalis and pubococcygeus avulsion from the pubic bone during vaginal delivery produces a levator hiatus defect detectable by 3D transperineal ultrasound as loss of the pubovisceral muscle insertion; the defect is associated with pelvic organ prolapse development in later life and cannot be repaired surgically, making prophylactic caesarean section a consideration in at-risk deliveries.
