Levator Ani
Levator ani is the main pelvic floor muscle group that elevates and supports the pelvic viscera.
The levator ani is a broad, thin sheet of skeletal muscle that forms the majority of the pelvic diaphragm. It is essential for supporting pelvic organs, maintaining continence, and resisting intra-abdominal pressure. The muscle group spans from the inner surface of the pelvis to the coccyx and walls of pelvic viscera. It is composed of three parts: puborectalis, pubococcygeus, and iliococcygeus. Together, these muscles provide dynamic support for the pelvic floor and play a vital role in defecation, urination, sexual function, and childbirth.
Structure
The levator ani arises from the inner surface of the pelvis and converges posteriorly around the midline structures. It is paired, with each side forming a hemidiaphragm. The two sides meet at a central raphe posterior to the anal canal.
Subdivisions of Levator Ani
| Part | Origin | Insertion |
|---|---|---|
| Puborectalis | Posterior surface of pubic bodies (both sides) | Loops behind the anorectal junction, forming a sling |
| Pubococcygeus | Pubis and anterior tendinous arch | Coccyx, anococcygeal ligament, and perineal body |
| Iliococcygeus | Tendinous arch of obturator internus fascia and ischial spine | Coccyx and anococcygeal ligament |
Location
The levator ani is located within the lesser pelvis, forming the majority of the pelvic floor. It lies medial to the obturator internus muscle and stretches from the pubic bone anteriorly to the coccyx posteriorly. The urogenital hiatus (for the urethra and vagina) and anal hiatus (for the anal canal) pass through the muscle, allowing passage of pelvic organs while maintaining muscular support.
Function
- Pelvic Organ Support: Maintains the position of the bladder, rectum, uterus, and prostate
- Continence Control: Puborectalis forms a sling around the anorectal junction, helping maintain fecal continence by creating the anorectal angle
- Closure of Pelvic Outlet: Provides a muscular seal to resist downward pressure from the abdominal cavity
- Functional Assistance: Involved in defecation, micturition, sexual function, and parturition
Innervation
- Nerve to levator ani (S3–S4): Primary motor supply
- Inferior rectal branch of pudendal nerve (S2–S4): Also contributes
Relations
| Structure | Relation to Levator Ani |
|---|---|
| Obturator internus | Lateral to levator ani; separated by the tendinous arch |
| Rectum | Passes through the anal hiatus, supported by puborectalis sling |
| Urethra | Passes anteriorly through the urogenital hiatus |
| Vagina (female) | Passes through the urogenital hiatus; surrounded by pubovaginal fibers |
Clinical Significance
- Pelvic Floor Dysfunction: Weakness or injury can lead to urinary or fecal incontinence, organ prolapse, and chronic pelvic pain
- Childbirth Injury: Vaginal delivery can stretch or tear pubococcygeus and puborectalis, especially during prolonged or forceful labor
- Levator Ani Syndrome: Characterized by chronic anorectal pain thought to be due to spasm or tension in the levator ani muscles
- Kegel Exercises: Strengthening of the levator ani, especially pubococcygeus, can improve continence and pelvic support
- Surgical Landmark: Important consideration in pelvic surgeries, including hysterectomy, prostatectomy, and rectal procedures
Last updated on May 10, 2025
