Lecture 16: Walls and Floor of Pelvis Flashcards
Anterior Wall
pubic bones (body and rami) and pubic symphysis
Lateral Walls
obturator foramen, obturator membrane, obturator internus muscle, tendinous arch of the levator ani muscle
Posterior Wall
sacrum, ilium, posterior sacroiliac joint ligs, piriformis muscle
Floor= pelvic diaphragm
- covers the pelvic outlet
- thicker and stronger than respiratory diaphragm to regulate abdominal pressure
- supports the abdominopelvic organs
What are the functions of the pelvic diaphragm?
- micturition
- defecation
- respiration
- childbirth
What makes up the pelvic diaphragm?
- Coccygeus muscle
- Levator Ani
- Urogenital hiatus
Coccygeus muscle attachments and actions
P: ischial spine
D: inferior end of sacrum/coccyx
N: sacral plexus
A: supports pelvic viscera and flexes the coccyx
Levator Ani
- made up of the puborectalis, pubococcygeus, and iliococcygeus
- P: body of pubis, tendinous arch of obturator fascia, and ischial spine
- D: perineal body, coccyx, anococcygeal lig, walls of anal canal
- N: sacrococcygeal plexus
What is the action of the Levator Ani?
form pelvic diaphragm, support pelvic viscera, resist increase in intra abdominal pressure
Puborectalis
- U-shaped muscular sling playing a major role in maintaining fecal continence
- forms the external anal sphincter
Pubococcygeus
runs from pubis to tip of coccyx
Iliococcygeus
runs from tendinous arch (ilium & pubis) to coccyx
What is the Urogenital Hiatus?
- V-shaped opening in pelvic diaphragm between puborectalis muscle
- runs from pubic symphysis to rectum
- contains perineal structures
What are the structures of the Urogenital Hiatus
a) deep transverse perineal muscle
b) external urethral sphincter/compressor urethra
c) perineal body
External urethral sphincter/compressor urethra
- inferior to pelvic diaphragm in perineum, thin muscle called constrictor urethra
- contains vagina in females
