Pelvic Floor Anatomy Flashcards
What is the normal position of the pelvic bone?
Vertical (tilted forward)
What is the true pelvis?
(lesser! pelvic cavity)
-It is the space between the pelvic inlet and pelvic outlet.
What does the pelvic diaphragm separate?
Separates the pelvic cavity from the perineum.
What muscle makes up the pelvic diaphragm?
Levator ani
What is the only item that goes through the pelvic diaphragm?
Rectum
What muscle forms the Obturator Foramen?
Obturator internus
What goes through the Obturator internus?
Obturator artery and vein
What is the thickening on the wall of the Obturator internus?
Tendinous arch of the Obturator Internus
What does the external sphincter consist of?
Fibers from the pelvic diaphragm
What is the ischioanal fossa?
Surrounds the Rectum and is a fat-filled space. It is fatty to accommodate the rectum bloating and emptying
How can you describe the pelvic diaphragm?
It is a funnel shaped sling
-A “shed roof” having from the tendinous arch of the obturator internus.
What is the Tendinous arch of the Obturator Internus?
A thickened region of the deep fascia of the muscle.
What does the obturator fascia form?
Obturator fascia also forms the pudendal canal –> pudendal nerve, artery and vein come through after exiting the sciatic foramen
What muscles make up the pelvic diaphragm?
- Levator ani
- Coccygeus
Where is the Coccygeus found?
On the inside of the sacrospinous ligament
What is the order of the Vagina, Urethra and Rectum from front to back?
Urethra, Vagina, Rectum
What two muscles is the Levator Ani the collective name for?
- Iliococcygesus muscle
- Pubococcygeus muscle
What is the Pubococcygeus muscle often divided into?
- Puborectalis muscle (puborectal sling)
2. Levator prostatae in males or Pubovaginalis in females
Where is the Coccygeus muscle?
It is a slip of muscle that lies on the deep surface of the sacrospinous ligament.
-In dogs this muscle pulls the tail between the legs
Where is the puborectal sling and what is its function?
(Puborectalis muscle) encircles the rectum. Normally, the muscle is contracted, kinking the rectum and contributing to sphincteric control.
What happens to the Puborectalis muscle during defecation?
The muscle relaxes (parasympathetic, via S2,3,4) allowing the anorectal junction to straighten
What is the Urogenital diaphragm?
A little layer of muscle that holds up and in the bladder, reproductive organs.
What does the puborectal sling do?
Creates a kink in the rectum. It stops movement of feces through rectum like a kink in a garden hose
What state is Puborectalis commonly in? What happens under parasympathetic stimulation?
It is tonically contracted. Under parasympathetic stimulation, during defamation, it relaxes, allowing the anorectal angle to increase (straighten)
What does the Puborectal sling act as?
A sphincter itself when contracted.
Where does the Coccygeus muscle lie?
Just above the Sacrospinal ligament (from sacrum to the ischial spine/sacrospinal ligament)
What makes up the external anal sphincter?
Fibers of the Levator Ani (pelvic diaphragm) blend with the outer longitudinal fibers of the rectum forming a thickened band, the external anal sphincter.
How is the internal anal sphincter controlled?
Parasympathetically
How is the external anal sphincter controlled?
Voluntarily
What forms the lateral muscular wall of the pelvis?
Obturator internus
What forms the posterior muscular wall of the pelvis?
Piriformis
What does the Ischial spine mark?
- Posterior edge of the levator ani
- Attachment of the coccygeus
- Marks narrowest diameter of pelvis, an important measure in OB
What nerve location does the Ischial spine mark?
Pudendal nerve - where it exists the greater sciatic foramen and enters the lesser sciatic formen
What identifies where the anesthetic should be deposited for a pudendal block?
Ischial spin (location of pudendal nerve block)
What is the only thing that goes through the pelvic diaphragm without support?
Rectum
What ligament attaches at the ischial spine?
Sacrospinous ligament
What is the action of the pelvic diaphragm?
- Supports the pelvic floor and the organs that pierce it
- Resists outward thrusts accompanying increases in intra-abdominal pressure
- Assists in defecation and urination
Portions of the pelvic diaphragm surrounding hollow organs…
…have specialized to become sphincter for that organ.
When does Rectal Prolapse occur?
When there is a loss of tone in the muscles that normally create an angle between rectum and anal canal (puborectalis).
What things cause Rectal Prolapse?
- Chronic straining to have bowel movements
- Strain during childbirth
- Some neurological disorders
- Disruption of the perineal body, as in episiotomy, may also precipitate rectal prolapse.
What is difficult to distinguish between?
Prolapsed internal hemorrhoids and prolapsed rectum - but hemorrhoids are far more common.
What two things often occur together?
Internal and external hemorrhoids often occur together.
What does rectal prolapse look like?
It has concentric folds of rectal mucosa. It is difficult to distinguish between prolapsed internal hemorrhoids and prolapsed rectum.
