Perineum

• Perineum

  • Anatomical region located in lower pelvis and plays role in both urinary and reproductive functions
  • Location: diamond shaped area between pubic symphysis (ant) and coccyx (post). Extends lat between the ischial tuberosities.

  
• Perineum boundaries

  • Anterior: pubic symphysis
  • Posterior: coccyx
  • Lateral: ischial tuberosities
  • Superior: pelvic diaphragm
  • Inferior: skin and fascia

  Its divided into anterior urogenital triangle and posterior anal triangle by an imaginary line passing between the 2 ischial tuberosites

  
• Contents of perineum

  • Perineal body
  • Annococcygeal body
  • External genitalia
  • Lower ends of urethra
  • Vagina
  • Anal canal
• Anococcygeal body

  • Complex muscolotendinous structure located between anterior aspect of coccyx and posterior wall of anorectal canal embedded in pelvic floor
  • Supports pelvic floor, providing attachment points for muscles and contributing to stability of pelvic organs.
• Perineal body

  • Fibromuscular mass located between in midline of perineum between urogenital and anal triangles.
  • Lies in subcutaneous tissue, posterior to vaginal vestibule and anterior to anal canal and anus
  • Provides support to pelvic floor
  • Point of attachment for pelvic muscles

  
• Perineum is divided into

  • Anterior anal region: contains anal canal canal
  • Posterior urogenital region: contains external urogenital organs

  Most important vasculature in perineum are the pudendal nerve and internal pudendal vessels located in lat. wall of ischional fossa.

  
• Anal triangle

  • Contains anal canal and ischiorectal fossae

  
• Anal canal

  • 4cm long
  • Begins as continuation of rectal ampula 1inch in front of tip of coccyx (anorectal junction)
  • Passes downwards and backwards and ends at anus (lower opening)

  Relations:

  Anterior: perineal body and urogenital diaphragm

  Posterior: anococcygeal body

  Lateral: ischiorectal fossa
• Anal sphincter

  • Internal anal sphincter( involuntary): covers aupper 2/3 of anal canal (ANS), formed by thickening of circular layer of smooth muscles
  • External sphincter( voluntary): covers lower 2/3 pf anal canal. Formed by skeletal muscles divided into subcutaneous part, superficial part attached to perineal body and coccyx and deep part.
  • External sphincter is supplied by pudendal nerve