perineum

• Perineum


  A diamond-shaped region positioned inferiorly to the pelvic floor
• Perineum

  • Peripheral boundary is the pelvic outlet
  • Ceiling is the pelvic diaphragm
  • Narrow lateral walls are formed by the walls of the pelvic cavity below the attachment of the levator ani muscle

  
• Regions of the perineum

  • Urogenital triangle
  • Anal triangle

  
• Urogenital triangle


  Associated with the openings of the urinary systems and the reproductive systems, anchors the external genitalia

  
• Anal triangle


  Contains the anus and the external anal sphincter
• Perineal membrane


  A thick fibrous sheet that fills the urogenital triangle, has a free posterior border anchored to the perineal body and attached laterally to the pubic arch

  
• Levator ani muscle


  • Arises from the body of the pubis, inserts on the coccyx, anococcygeal raphe, external anal sphincter, walls of the prostate, rectum, anal canal, and central tendon of the perineum
  • Supports and slightly raises the pelvic floor
• Coccygeus muscle


  • Arises from the spine of the ischium and the sacrospinous ligament, attaches to the coccyx and lower portion of the sacrum
  • With the levator ani, supports the pelvic floor, draws the coccyx forward after it has been pushed back
• Posterior anal triangle


  Bounded by the perineal body, ischial tuberosities, sacrotuberous ligaments, and coccyx, contains the levator ani muscle and external anal sphincter
• Anterior urogenital triangle


  Bounded anteriorly by the inferior margin of the pubic symphysis, laterally by the ischiopubic rami, and posteriorly by an imaginary line between the ischial tuberosities

  
• Structures in the anterior urogenital triangle


  • Perineal membrane
  • Deep perineal pouch
  • Superficial perineal pouch
  • Superficial perineal fossa (Fascia of Colles)

  
• Deep perineal pouch


  Contains erectile structures (penis in men, clitoris in women) and muscles

  
• Erectile structures in the deep perineal pouch

  • Penis in men
  • Clitoris in women

  
• The greater vestibular glands (Bartholin's glands) are in the superficial perineal pouch in women
• The bulbo-urethral gland is in the deep perineal pouch in men
• Deep perineal pouch


  + superior to the perineal membrane

  + thin region

  + contains : layer of skeletal muscle

  neurovascular tissues
• External urethal sphincter


  among the skeletal muscles in the pouch