Pelvic Floor Anatomy and Function

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Pelvic Floor Anatomy and Function - The Body's Hammock

Female Pelvic Viscera and Perineum

  • 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. Female Pelvic Floor Muscles and Hiatuses

⭐ 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 Pelvic Floor Muscles and Hiatuses

⭐ 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.

Practice Questions: Pelvic Floor Anatomy and Function

Test your understanding with these related questions

Which muscle is a key component of the pelvic diaphragm?

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Flashcards: Pelvic Floor Anatomy and Function

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Injury to the levator ani muscles results in _____ hypermobility and can result in prolapse of the anterior vaginal wall and the bladder

TAP TO REVEAL ANSWER

Injury to the levator ani muscles results in _____ hypermobility and can result in prolapse of the anterior vaginal wall and the bladder

urethral

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