Female Perineum

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Female Perineum: Overview & Boundaries - Diamond Design

  • Diamond-shaped region inferior to pelvic diaphragm, situated between the thighs.
  • Boundaries (Diamond Shape):
    • Anteriorly: Pubic symphysis & arcuate pubic ligament.
    • Posteriorly: Tip of coccyx.
    • Anterolaterally: Ischiopubic rami.
    • Posterolaterally: Sacrotuberous ligaments.
    • Roof: Pelvic diaphragm (Levator ani, Coccygeus muscles).
    • Floor: Skin & perineal fascia.
  • Subdivisions (by transverse line between ischial tuberosities):
    • Urogenital triangle (anterior): Contains external genitalia & urethra.
    • Anal triangle (posterior): Contains anal canal & ischioanal fossae.

Female perineum boundaries and triangles

⭐ The perineal body (central tendon of the perineum) is a key fibromuscular structure providing support and is often incised during episiotomy or torn during childbirth.

Female Perineum: Urogenital Triangle - Frontal Formations

Female perineum with urogenital and anal triangles

  • Urogenital Triangle (UGT): Anterior part of perineum.
    • Boundaries: Pubic symphysis (anteriorly), ischiopubic rami (laterally), superficial transverse perineal muscle (posteriorly).
  • Superficial Perineal Pouch: Space inferior to perineal membrane.
    • Contents:
      • Erectile tissues: Crura of clitoris, bulbs of vestibule.
      • Muscles: Ischiocavernosus, bulbospongiosus, superficial transverse perineal.
      • Glands: Bartholin's glands (greater vestibular).
      • Vessels & Nerves: Perineal branches.
  • Deep Perineal Pouch: Space superior to perineal membrane.
    • Contents:
      • Urethra.
      • External urethral sphincter.
      • Compressor urethrae, Sphincter urethrovaginalis.
      • Dorsal neurovasculature of clitoris.

⭐ Bartholin's glands (greater vestibular glands), located in the superficial perineal pouch, are homologous to the bulbourethral glands in males and are clinically significant due to their susceptibility to cysts and abscesses (Bartholinitis).

Female Perineum: Anal Triangle & Fascia - Rear Region Rundown

  • Anal Triangle: Posterior perineal region.
    • Boundaries: Coccyx (post.), sacrotuberous ligaments (posterolat.), ischial tuberosities line (ant.).
    • Contents: Anal canal, sphincters (external/internal), ischioanal fossae.
  • Ischioanal Fossa: Fat-filled, lateral to anal canal.
    • Boundaries: Skin (floor), levator ani (roof/medial), obturator internus (lateral).
    • Contents: Fat, inferior rectal neurovasculature. Pudendal canal (Alcock's) in lateral wall.

    ⭐ The ischioanal (ischiorectal) fossa, filled with fat, is a common site for abscess formation, which can spread easily due to the nature of its contents and poorly defined fascial boundaries.

  • Fascia:
    • Anal fascia (inf. pelvic diaphragm fascia): Medial wall of ischioanal fossa.
    • Obturator fascia: Lateral wall, forms pudendal canal.

Female Perineum Muscles and Structures

Female Perineum: Neurovasculature & Clinicals - Lines, Drains, Pains

  • Neurovasculature:
    • Artery: Internal pudendal artery (from internal iliac a.). Branches supply perineal structures.
    • Vein: Internal pudendal vein (accompanies artery, to internal iliac v.).
    • Nerve: Pudendal nerve (S2,S3,S4). 📌 S2,3,4 keeps the pee and poo off the floor. Main branches: inferior rectal, perineal, dorsal nerve of clitoris.
  • Lymphatic Drainage:
    • Superficial inguinal nodes: Most of vulva, lower vagina, perineal skin.
    • Deep inguinal/External iliac nodes: Clitoris, labia minora.
    • Internal iliac nodes: Upper vagina, deep perineal structures.
  • Clinicals:
    • Pudendal Nerve Block: Landmark: Ischial spine. For childbirth analgesia, perineal procedures.
    • Episiotomy: Surgical cut. Types: Mediolateral (common, ↓risk to sphincter), Median (↑risk).
    • Perineal Tears (Childbirth):

Female Perineum Neurovasculature and Muscles

⭐ The pudendal nerve (S2, S3, S4) is the primary somatic nerve of the perineum; a pudendal nerve block, often performed by palpating the ischial spine, provides anaesthesia for childbirth and perineal procedures.

High‑Yield Points - ⚡ Biggest Takeaways

  • Pudendal nerve (S2-S4) is the primary nerve of the perineum.
  • Perineal body: crucial fibromuscular support, prone to obstetric tears.
  • Bartholin's glands: posterolateral to vaginal orifice, site of cysts/abscesses.
  • Mediolateral episiotomy: preferred to avoid anal sphincter injury.
  • Urogenital triangle: contains external genitalia, urethral and vaginal openings.
  • Ischioanal fossae: lateral to anal canal, common site for abscesses.
  • Clitoris: erectile tissue, homologous to penis, key erogenous zone.

Practice Questions: Female Perineum

Test your understanding with these related questions

Following delivery, a tear involving the perineum and external anal sphincter with intact mucosa is classified as which grade?

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Flashcards: Female Perineum

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Perineum, vulva, lower vagina are innervated by spinal segments _____

TAP TO REVEAL ANSWER

Perineum, vulva, lower vagina are innervated by spinal segments _____

S2-S4

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