Pelvic Diaphragm

Question 1

What is the major support structure for pelvic viscera?

Answer 1

the pelvic diaphragm

Question 2

What does the pelvic diaphragm consist of?

Answer 2

the following muscles and their fascial coverings:

1. coccygeus (ischiococcygeus) muscle
2. levator ani muscle: the major constituent of the pelvic diaphragm

Question 3

What are the openings within the pelvic diaphragm?

Answer 3

• urogenital hiatus: transmits urethra in males and urethra and vagina in females
• anal aperture: in both sexes

Question 4

What is the origin, insertion, nerve supply, and function of the coccygeus (ischiococcygeus) muscle?

Answer 4

• O: ischial spine and sacrospinous ligament
• I: coccyx and lower part of sacrum
• N: anterior primary rami of 3rd and 4th sacral nerves
• F: supports pelvic viscera, draws coccyx forward

Question 5

What is the origin, insertion, nerve supply, and function of the levator ani muscle?

Answer 5

• O: body of pubis, tendinous arch, ischial spine
• I: coccyx and anococcygeal ligament
• N: anterior primary rami of 3rd and 4th sacral nerves, perineal branch of pudendal nerve
• F: as a whole, supports pelvic viscera; specialized parts of the levator ani perform other functions

Question 6

What are the parts of the levator ani muscle?

Answer 6

1. iliococcygeus: most posterior part
2. pubococcygeus: main part
3. puborectalis

Question 7

What are the subdivisions of the pubococcygeus?

Answer 7

1. Puboprostaticus: forms a sling around the urethra beneath the prostate in the male
2. Pubovaginalis: forms a sling around the urethra and vagina in the female
3. Puboanalis: attaches to the anorectal junction

Question 8

What is the function of the puboprostaticus and pubovaginalis?

Answer 8

Function in micturition: important for urinary continence

Question 9

What does the puborectalis form?

Answer 9

fibers from each side unite behind the anorectal junction to form the puborectal sling

Question 10

What are the functions of the puborectalis?

Answer 10

• functions to maintain the angle at the anorectal junction (perineal flexure)
• relaxes during defecation: important for fecal continence
• also functions to direct the fetal head forward during parturition

Question 11

What is the tendinous arch of levator ani?

Answer 11

a curved thickening of the obturator fascia which gives origin to parts of the pubococcygeus and iliococcygeus

Question 12

Misalignment of the sacrum with impingement of the nerves to the levator ani may affect what?

Answer 12

• fecal continence
• urinary continence
• parturition
• integrity of the pelvic floor