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Anatomy of perineum

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Anatomy of perineum

  1. 1. MOB TCD Perineum Professor Emeritus Moira O’Brien FRCPI, FFSEM, FFSEM (UK), FTCD Trinity College Dublin
  2. 2. MOB TCD Perineum • • • • • • Area below the levator ani Boundaries Pubic arch Ischial tuberosities Sacrotuberous ligament Coccyx
  3. 3. MOB TCD Perineal Triangles
  4. 4. MOB TCD Perineum • • • • Divided into two triangles Urogenital triangle Anal triangle Perineal body central point of perineum
  5. 5. MOB TCD Urogenital Triangle • Deep pouch • Superficial pouch • Perineal membrane separates the two • Deep is superior to perineal membrane • Roof is pelvic fascia
  6. 6. MOB TCD Deep Pouch in Male Membranous portion of the urethra • Sphincter urethra or external sphincter of bladder • Perineal nerve • Deep transverse perineal muscle •
  7. 7. MOB TCD Deep Pouch in Male • Bulbourethreal glands • Internal pudendal artery and branches • Artery to bulb • Dorsal nerve of penis • Branches of perineal nerve
  8. 8. MOB TCD Deep Pouch in Female • • • • • • • • Vagina Urethra Sphincter urethra or external sphincter of bladder Perineal nerve Deep transverse perineal muscle Internal pudendal artery Artery to bulb Dorsal nerve of clitoris
  9. 9. MOB TCD Sphincter Urethrae (Female) • Sphincter urethrae in the deep pouch • Also called external sphincter of bladder • Perineal branch of pudendal S 2,3
  10. 10. MOB TCD Perineal Membrane (Male) • • • • • • Piercing membrane Spongy urethrae Ducts of bulbourethral glands Artery to bulb Internal pudendal artery Deep and dorsal arteries of penis • Dorsal nerve of penis • Deep dorsal vein passes above membrane • Enters prostatic venous plexus
  11. 11. MOB TCD Superficial Pouch (Male)
  12. 12. MOB TCD Superficial Pouch (Male)
  13. 13. MOB TCD Superficial Pouch (Male)
  14. 14. MOB TCD Colles’ Fascia • Attached posteriorly to perineal membrane • Sides of pubic arch laterally • Deep fascia of thigh along a line drawn from pubic tubercle • Anterior floor of pouch • Layer of scrotum • Surrounds penis as far as glans • Passes up on to anterior abdominal wall
  15. 15. Membranous Layer of Superficial or Colles’ Fascia • Posterior attached to posterior border of perineal membrane • Anterior it forms floor of superficial pouch and forms layer of the scrotum • Surrounds penis as far as glans • Then on to anterior abdominal wall • Attached to fascia lata from a horizontal line from pubic tubercle • Rupture of spongy urethra is limited by the attachment of Colles’ fascia MOB TCD
  16. 16. MOB TCD Superficial Pouch (Male) • • • • Roof Perineal membrane Floor Colles’ or membranous layer of superficial fascia • Ruptured urethra in male • Urine limited by the attachments of Colles’ fascia in superficial pouch
  17. 17. MOB TCD Superficial Pouch (Male) • • • • • • • • • • Penis corpus spongiosum Corpora cavernosa Spongy urethra Bulbospongiosus muscle Ischiocavernosus muscle Superficial transverse perinei muscle Internal pudendal artery Deep and dorsal arteries of penis Dorsal nerves of penis Scrotal vessels and nerves
  18. 18. MOB TCD Contents Superficial Pouch (Male) • • • • • Root of penis Corpus spongiosum Bulb, body and glans Spongy portion of urethrae Crura and corpora cavernosa
  19. 19. MOB TCD Penis
  20. 20. MOB TCD Penis
  21. 21. MOB TCD Penis • Corpus spongiosum • Corpora cavernosa • Consists of erectile cavernous tissue • Each enclosed in a fibrous membrane, tunica albuginea • Surrounded by Colles’ Fascia
  22. 22. MOB TCD Penis • Deep artery enters crura of corpora cavernosa • Dorsal nerve of penis • Dorsal artery of penis • Deep dorsal vein lies on dorsum between Colles’s fascia and tunica albuginea • Passes above perineal membrane • Enters prostatic venous plexus
  23. 23. MOB TCD Penis • Erectile tissue • Helicine arteries • Fibrous saccules arterioles enter directly • Dorsal vein open • Parasympathetic causes erection L2,3,4 • Ejaculation is via the sympathetic impulses from L1-L2
  24. 24. MOB TCD Corpus Spongiosum • • • • • • • • • Bulb posterior dilatation Body (horizontal) Glans dilated anteriorly Spongy urethra Dilated posteriorly in the bulb Uniform in body Dilated in the glans Fossa navicularis Meatus vertical slit
  25. 25. MOB TCD Spongy Urethra
  26. 26. MOB TCD Spongy Urethra • • • • • Urethra unprotected Before it enters bulb Ducts of bulbo-urethral glands Enter intrabulbar fossa Littre’ glands end in navicular fossa
  27. 27. MOB TCD Muscles in Superficial Pouch (Male) • Bulbospongiosus muscle • Ischiocavernosus muscle • Superficial transverse perinei muscle • Supplied by perineal branches of pudendal nerve • Enter pouch by piercing Colles’ fascia
  28. 28. MOB TCD Vessels and Nerves • Deep and dorsal arteries of penis • Deep dorsal vein • Scrotal nerves • Perineal nerve • Dorsal nerve of penis
  29. 29. MOB TCD Lymphatics • Skin of scrotum to medial superficial inguinal glands • Testes to para aortic glands at L2
  30. 30. MOB TCD Nerve Supply • Preganglionic of sympathetic from L1 and L2 cause ejaculation • Parasympathetic preganglionic from S2,3,4 cause erection
  31. 31. MOB TCD Female Pelvis and Perineum
  32. 32. MOB TCD Superficial Pouch (Female) • • • • • • Mons pubis Labia majora Labia minora Dorsal prepuce Frenulum of glans Vestibule
  33. 33. MOB TCD Superficial Pouch (Female)
  34. 34. MOB TCD Superficial Pouch (Female) • • • • • • Urethra Vagina Clitoris Crura of clitoris Ischiocavernosa Bulbs of vestibule join, pass to glans • Bulbospongiosus • Bartholin’s or vestibular glands
  35. 35. MOB TCD Superficial Pouch (Female) • Crura and glans of clitoris • Covered by ischiocavernosus muscle • Bulbs of vestibule • Inferior greater vestibular or Bartholin’s glands beside vagina • Covered by bulbospongiosus muscle
  36. 36. MOB TCD Superficial Pouch (Female)
  37. 37. MOB TCD Superficial Pouch (Female) • Cutaneous anteriorly • Ilioinguinal nerve • Labial vessels and nerve posteriorly • Motor • Perineal branches of pudendal
  38. 38. MOB TCD Structure of Female Urethra • • • • • • Muscular layer continuous with bladder Spongy erectile tissue Plexus of veins Mucous membrane transitional Distal non-keratinising stratified squamous No fascia between lower two thirds of urethra and vagina
  39. 39. MOB TCD Vagina • Fornices, gutters which surround the cervix • Anterior shallow • Posterior deeper • Superior covered with peritoneum of the pouch of Douglas • Lateral: uterine artery above ureter
  40. 40. MOB TCD Vagina • Upper portion of the vagina is clasped • By the pubovaginalis portion of the levator ani • Bulbospongiosus muscles surrounds outlet • Hymen
  41. 41. MOB TCD Vagina • • • • Erectile tissue Muscular wall Pelvic fascia Non-keratinised stratified squamous epithelium • Urethra lower third anterior wall • No fascia between lower two thirds of urethra and vagina
  42. 42. MOB TCD Anal Triangle • Anal canal • Ischiorectal fossa
  43. 43. MOB TCD Anal Canal • Anorectal junction: below ampulla of rectum • Anus: 4 cm • Anterior: perineal body • Posterior: anococcygeal body • Lateral: ischiorectal fossae
  44. 44. MOB TCD Anal Canal • Upper two thirds • Columnar epithelium • Anal columns contain radicles of superior rectal artery and veins • 4, 7, 11 o’clock position • Anal valves along pectinate line • Anal sinus, Hilton white line; internal sphincter • Subcutaneous deep • Lower third skin
  45. 45. MOB TCD Muscles of Anal Canal • • • • • • • • • • Anorectal ring Internal sphincter Puborectalis Puborectal fascia External sphincter Deep; true sphincter Inferior rectal nerve Superficial S4 Subcutaneous; true sphincter Inferior rectal nerve
  46. 46. MOB TCD Muscles of Anal Canal • • • • • Anorectal ring Puborectalis Internal sphincter Upper two thirds Perianal fascia is medial to deep and superficial sphincter • Passes to lateral wall forms pudendal canal • Above subcutaneous sphincter
  47. 47. MOB TCD Blood and Nerve Supply • • • • • • Mucosa upper two thirds Superior rectal artery Autonomic nerves Lower third Inferior rectal Somatic nerves
  48. 48. MOB TCD Venous Drainage • • • • • • • Mucosa upper two thirds Superior rectal vein Portal system Lower third Inferior rectal vein Vein into systemic system Portal systemic anastomosis 4,7,11 o’clock
  49. 49. MOB TCD Lymphatic Drainage • Upper third • Pre-aortic inferior mesenteric • Waldeyer’s fascia passes from sacrum to the ampulla of rectum • Encloses superior rectal vessels and lymphatics • Internal iliac • Lower third • Inferior rectal cross ischiorectal fossa • Medial superficial inguinal glands
  50. 50. MOB TCD Embryology of Anal Canal • • • • Upper two thirds Cloaca Lower third Proctodeum
  51. 51. MOB TCD Ischiorectal Fossa • Wedge shaped fossa • Apex: origin of levator ani from obturator internus • Lunate fascia • Base: perianal fascia and subcutaneous fat • Medial: levator ani • External anal sphincters MOB TCD
  52. 52. MOB TCD Ischiorectal Fossa (Female) • Anterior: posterior border perineal membrane • Posterior: sacrotuberous ligament, gluteus maximus
  53. 53. MOB TCD Ischiorectal Fossa (Male) • Lateral: fascia on medial aspect of obturator internus ani • Pudendal canal • Ischial tuberosity
  54. 54. MOB TCD Ischiorectal Fossa • Soft ischiorectal fat • Lunate fascia above the fat • Inferior rectal vessels pass above the fat to reach medial wall • Perineal branch of S4 Ischiorectal fossa
  55. 55. MOB TCD Pudendal Canal • • • • • • • Runs posterior to anterior Contents Pudendal nerve Inferior rectal nerve Dorsal nerve of penis or clitoris Perineal nerve Scrotal or labial nerves
  56. 56. MOB TCD Pudendal Block
  57. 57. MOB TCD Dermatomes
  58. 58. “BMJ Publishing Group Limited (“BMJ Group”) 2012. All rights reserved.”

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