Regional Anatomy of the Pelvis and Perineum Flashcards Preview

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Flashcards in Regional Anatomy of the Pelvis and Perineum Deck (17)
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Boundaries and anatomical relationships of subdivisions of pelvis & associated viscera

  • Bony pelvis 
    • Innominate bones (ileum, ischium, pubis)
    • Sacrum and coccyx
  • Pelvic inlet
    • From sacral promontory to pubic symphysis
  • Pelvic outlet
    • From pubic symphysis to coccyx
    • Following ischiopubic ramus, ischial tuberosity, and sacrotuberous ligament
  • False (greater) pelvis
    • Superior to pelvic inlet
    • Part of abdominal cavity
  • True (lesser) pelvis
    • From pelvic inlet to pelvic outlet (at pelvic diaphragm)
    • Pelvic cavity (contains pelvic viscera)
    • Pelvic walls consist of bone, ligaments (sacrospinous and sacrotuberous), and muscles (piriformis, obturator internus, with fascia)
    • Pelvic floor consists of pelvic diaphragm (levator ani muscles, coccygeus muscles with superior and inferior fascia covering muscles)


Pelvic diaphragm

  • Levator ani muscle
  • Coccygeus muscle
  • Fascia:
    • Superior
    • Inferior


Internal pelvic viscera: rectum

  • Supported by and passes through muscular portion of pelvic diaphragm
  • Diaphragm forms a sling, when contracted, aids external and internal anal sphincters in controlling defecation
  • Pelvic diaphragm supports rectum and pelvic viscera


Urogenital diaphragm

  • Deep transverse perineus muscles in deep perineal pouch
  • Superior fascia
  • Inferior fascia (perineal membrane)
    • Platform for the external genitalia



  • Diamond shaped region between abducted thigh 
  • Inferior to pelvic diaphragm


Anatomical relationships between uterus, ovaries, subdivisions of broad ligament

  • Ovaries
    • Produce eggs
    • Endocrine organ
  • Uterine (fallopian) tubes
    • Fimbriae: collect ovulated egg
    • Infundibulum
    • Ampulla: normal site of fertilization
    • Isthmus 
  • Uterus
    • Fundus
    • Body
    • Cervix: projects into upper end of vagina


Ligaments of female internal reproductive organs

  • Broad ligament: peritoneal fold
    • Mesovarium:
      • Supports ovary and surrounds suspensory and ovarian ligaments and vessels
    • Mesosalpinx:
      • Surrounds and supports uterine tubes
    • Mesometrium:
      • Broad ligament inferior to mesosalpinx surrounding uterine vessels
  • Cardinal ligaments
    • Located at base of mesometrium, extending from cervix to pelvic wall



  • Produce spermatozoa in seminiferous tubules
  • Endocrine organ
  • Rete testis
    • Collecting chamber for spermatozoa
  • Efferent ductules
    • Connects rete testis with epididymis



  • Stores and functions in maturation of spermatozoa
  • Head
  • Body
  • Tail
    • Continuous with ductus deferens


Ductus deferens & ejaculatory ducts

  • Ductus deferens
    • Muscular (smooth muscle) tube that transports spermatozoa from epididymis to ejaculatory ducts
  • Ejaculatory ducts
    • Combined ducts of ampulla (ductus deferens) and seminal vesicle
    • Empties into prostatic urethra


Seminal vesicles and prostate

  • Seminal vesicle
    • Contributes secretions to semen 
  • Prostate
    • 30-40 individual glands
    • Individual ducts drain into prostatic urethra
    • Contributes secretions to semen


Innervation of perineum

  • Genitofemoral nerve
  • Ilioinguinal nerve
  • Pudendal nerve
  • Posterior femoral cutaneous nerve


Boundaries and contents of superficial and deep perineal pouches

  • Superficial pouch
    • From superficial perineal fascia (Colle's fascia) to perineal membrane
    • Encloses erectile tissues and their muscles
  • Deep pouch
    • From perineal membrane to superior fascia of urogenital diaphragm
    • Encloses deep transverse perineus muscle and urethral sphincter (skeletal muscles)


Areas of the pelvic bones most commonly fractured & clinical implications of the pubo-obturator fracture

  • Pubic rami
    • At risk during AP compression of pelvis (crush accident, heavy object fall)
    • High risk of complication due to damage to urinary bladder and urethra
    • Straddle injury (fracture of all 4 pubic rami) --> serious loss of pelvic stability
  • Acetabulum
    • At risk during fall on the feet from height
    • Forces from ground drive head of femur into acetabulum
    • Lateral compression of pelvis places acetabula and iliac blades at risk


Most common injuries to the pelvic floor during childbirth

  • Tearing injuries
    • Grade 1 = superficial tissues
    • Grade 2 = some tearing of muscles
    • Grade 3 = tear extends to anal sphincter
  • Grade 2+ tears most commonly pubococcygeous and puborectalis parts of levator ani
  • Episiotomy (intentional cut) intends to decrease traumatic tearing of perineum 
    • Typically not performed anymore
    • May be employed in cases of fetal distress, if descent of fetus becomes arrested, or when delivery with assistance of instruments is planned


BPH and urinary implications

  • Common after middle age - undergoes hormone-induced hypertrophy
  • Especially marked in middle lobe area between urethra and ejaculatory ducts
  • Enlarging prostate projects into bladder - distorts and compresses prostatic urethra
    • Impedes urination
    • May cause nocturia, dysuria, and/or urgency
    • Increases risk of bladder infxns
  • Prostate can be palpated via DRE
    • Close relationship to anterior wall of rectum + full bladder --> makes gland more easily palpable
  • Part or all of prostate may be surgically removed
    • Newer approach passes through urethra


Anatomic etiology & clinical implications of testicular torsion and varicocele

  • Testicular torsion
    • Spermatic cord becomes twisted, usually just superior to upper pole of testis
    • Most commonly linked to congenital malformation of processus vaginalis
    • Obstructs venous drainage --> edema --> blocks arterial supply to testis --> avascular necrosis of testis
  • Varicocele of testis ("bag of worms" scrotum)
    • Abnormal enlargements of pampiniform plexus of veins in spermatic cord
    • Caused by incompetent/absent valves within testicular veins --> pooling of blood or backflow
    • L-sided varicocele more common
    • Present in 10-15% of males