Pelvic Floor Anatomy and Function

Pelvic Floor Anatomy and Function - The Body's Hammock

• Musculofascial sling supporting pelvic viscera; forms base of abdominopelvic cavity.
• Key Components:
  • Pelvic Diaphragm (main support):
    • Levator ani (puborectalis, pubococcygeus, iliococcygeus).
    • Coccygeus muscles.
  • Perineal Membrane & associated muscles: Urogenital support.
• Innervation: Primarily Pudendal nerve (S2-S4); direct sacral nerve branches.
• Functions: Supports organs, maintains continence (urinary/fecal), sexual function, aids childbirth.

⭐ Damage to the levator ani or pudendal nerve during childbirth is a major risk factor for pelvic organ prolapse and incontinence.

Pelvic Floor Anatomy and Function - The Core Support

• Muscular sling supporting pelvic viscera (bladder, uterus, rectum).
• Pelvic Diaphragm: Forms pelvic floor.
  • Levator Ani: Major part.
    • Puborectalis: U-shaped; key for anorectal angle & fecal continence.
    • Pubococcygeus: Pubis to coccyx.
    • Iliococcygeus: Arcus tendineus to coccyx.
  • Coccygeus (Ischiococcygeus): Posterior; ischial spine to sacrum/coccyx.
• Innervation: Pudendal nerve (S2-S4), direct sacral branches.
• Functions: Organ support, continence (urinary/fecal), aids childbirth, defecation, sex.

⭐ Injury to Levator Ani (esp. pubococcygeus, puborectalis) during vaginal delivery is a major risk for pelvic organ prolapse & incontinence.

Pelvic Floor Anatomy and Function - The Front Line

• Urogenital Triangle: Anterior perineum. Houses external genitalia, urethral & vaginal openings.
• Perineal Membrane:
  • Dense fascia inferior to urogenital diaphragm. Closes urogenital hiatus anteriorly.
  • Supports urethra, vagina; anchors erectile tissues (clitoris/penile bulb).
• Perineal Body (Central Tendon):
  • Central fibromuscular mass. Between vagina/penile bulb and anus.
  • Crucial for posterior vaginal support, prevents prolapse. 📌 PBS: Perineal Body Support.

  ⭐ Perineal body: convergence for Bulbospongiosus, EAS, Transverse Perineals, parts of Levator Ani.

Pelvic Floor Anatomy and Function - The Support Network

• Connective Tissue Framework: Synergizes with muscles; vital for organ integrity and position.
  • Endopelvic Fascia: Fibroareolar sheath: collagen, elastin, smooth muscle.
    • Pubocervical fascia: Supports anterior vaginal wall & bladder.
    • Rectovaginal fascia: Supports posterior vaginal wall & rectum.
  • Pelvic Ligaments: Key condensations of endopelvic fascia providing suspension.
    • Cardinal Ligaments (Transverse Cervical): Primary support for uterus & upper vagina.
    • Uterosacral Ligaments: Suspend cervix & upper vagina posteriorly to sacrum.
• DeLancey's Levels of Vaginal Support: Critical 3-tier anatomical model.

![DeLancey's 3 levels of vaginal support](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Obstetrics_and_Gynecology_Urogynecology_Pelvic_Floor_Anatomy_and_Function/31d4f7f9-6a2c-4677-b4cd-a5529bb11d26.jpg)
> ⭐ Level I defects (uterosacral-cardinal complex) are the most common cause of uterine or vault prolapse.

Pelvic Floor Anatomy and Function - Nerves & Problems

• Nerve Supply:
  • Pudendal Nerve (S2-S4): Primary motor to external sphincters (urethral, anal); sensory to perineum. 📌 S2,3,4 keeps the Pudenda off the floor.
  • Levator Ani Nerve (S3-S4): Direct motor to levator ani muscles.
  • Autonomic Nerves: Sympathetic (hypogastric plexus) & Parasympathetic (pelvic splanchnic, S2-S4) control bladder/bowel function.
• Common Problems (Dysfunctions):
  • Urinary Incontinence (Stress, Urge)
  • Fecal Incontinence
  • Pelvic Organ Prolapse (POP)
  • Sexual Dysfunction
  • Chronic Pelvic Pain

⭐ Pudendal nerve injury (e.g., childbirth, cycling) can lead to fecal/urinary incontinence, perineal pain, or sexual dysfunction.

High‑Yield Points - ⚡ Biggest Takeaways

• Levator ani muscles form the pelvic diaphragm, providing primary pelvic support.
• Pudendal nerve (S2-S4): key for perineal sensation & external sphincter motor control.
• Endopelvic fascia: provides crucial connective tissue (suspensory) support for pelvic organs.
• DeLancey's Levels: Level I (apical suspension), Level II (mid-vaginal attachment), Level III (distal fusion) define vaginal support.
• Perineal body: central fibromuscular structure for posterior pelvic floor integrity.
• Intact pelvic floor function: essential for organ support, urinary/fecal continence, and sexual function.