Pelvic and Perineal Myology

Question 1

What are the muscles of the urogenital diaphragm

Answer 1

External urethral sphincter m
Deep transverse perineal m
Compressor urethrae m
Female: urethrovaginal sphincter m.

Question 2

What are the levator ani ms?

Answer 2

Puborectalis m.
pubococcygeus m
iliococcygeus m

Question 3

What muscles make up the pelvic diaphragm?

Answer 3

levator ani ms and coccygeus m.

Question 4

What is the perineal body?

Answer 4

Irregular fibromuscular mass in the midline between the anal canal and the perineal membrane
Contains collagenous and elastic fibers
Central ‘tendon’ of the pelvic and urogenital diaphragms

Question 5

Describe the superficial transverse perineal m

Answer 5

O: Ischiopubic ramus and ischial tuberosity
I: perineal body
A: Supports and fixes perineal body, supports abdominopelvic viscera, resists increases in intraabdominal pressure
N: Deep perineal N

Question 6

Describe O,I,A and N of ischiocavernosus m

Answer 6

O: Ischiopubic ramus and ischial tuberosity
I: medial aspect of the crus of the penis or clitoris and perineal membrane medial to the crura
A: Maintains erection of penis or clitoris by compressing venous drainage, forcing blood from crura into the body of the penis or clitoris
N: Deep perineal n

Question 7

Describe O,I,A and N of bulbospongiosus m in males

Answer 7

O: perineal body, median raphe and ventral bulb of penis
I: perineal membrane, fascia of bulb of penis and corpus spongiosum and corpora cavernosa of the penis
A: Support and fix perineal body, compress bulb of penis, assist erection by compressing venous drainage, forcing blood from root of the penis to the body of the penis, expels final drops of urine/semen from urethra
N: Deep perineal n

Question 8

Describe O, I, A, and N of bulbospongiosus m in females

Answer 8

O: perineal body
I: fascia of bulb of the vestibule of vagina, pubic arch, and fascia of corpora cavernosa of the clitoris
A: compresses vaginal orifice, assist in erection of bulbs of vestibule of vagina and compresses the greater vestibular gland
N: Deep perineal n

Question 9

O, I, A, and N of the external urethral sphincter m

Answer 9

O: surrounds the urethra
I: surrounds the urethra
A: constrict urethra maintaining urinary continence
N: dorsal n of the penis or clitoris

Question 10

O, I, A, and N of compressor urethrae M.

Answer 10

O: ischiopubic ramus and ischial tuberosity
I: median raphe and urethra via external urethral sphincter m
A: constrict urethra maintaining urinary continence
N: dorsal n of the penis or clitoris

Question 11

O, I, A, and N of urethrovaginal sphincter m

Answer 11

• slips of the external urethral sphincter m that also surrounds the vagina
  O: ischiopubic ramus and ischial tuberosity
  I: external wall of the vagina
  A: compresses the vagina
  N: dorsal nerve of the clitoris

Question 12

O, I, A and N of the deep transverse perineal m

Answer 12

O: ischiopubic ramus, and ischial tuberosity
I: median raphe, perineal body and external anal spinchter
A: support and fix perineal body, supports abdominopelvic viscera and resists increases in intraabdominal pressure
N: deep perineal n

*smooth m in females

Question 13

O, I, A, and N of external anal sphincter m

Answer 13

O: skin and fascia surrounding anus and anococcygeal body
I: perineal body
A: constricts the anal canal during peristalsis, resists defecation, supports and fix perineal body
N: inferior rectal n

Question 14

Describe internal anal sphincter m

Answer 14

involuntary sphincter surrounding superior 2/3 of anal canal

Thickening of circular muscular layer innervated by parasympathetic fibers from pelvic splanchnic n

Question 15

O, I, A, and N of puborectalis M

Answer 15

O: posterior aspect of the pubic body
I: external wall of the rectum and anal canal
A: maintain anorectal flexure, supports pelvic viscera, resists increases in intraabdominal pressure
N: Nerve to levator ani m. (S4), inferior rectal n., branches of coccygeal plexus

Thick, narrow, medial most part of levator ani ms

Question 16

O, I, A, N of pubococcygeus m

Answer 16

O: Posterior aspect of the pubic body and anterior most part of the tendinous arch of obturator fasccia
I: coccyx, anococcygeal body, contralateral pubococcygeus m
A: supports pelvic viscera, resists increases in intraabdominal pressure

Thin, wide, main part of the levator ani m

Question 17

What levator ani m produces several small slips of muscle that extends to nearby structures? Name the muscles

Answer 17

Pubococcygeus m

• puboperinealis m
• puboanalis m
• levator prostate m/pubovaginalis m

Question 18

O, I, A, N of iliococcygeus m

Answer 18

O: posterior part of the tendinous arch of obturator fascia and ischial spine
I: coccyx and anococcygeal body
A: supports pelvic viscera, resists increases in intraabdominal pressure
N: Nerve to the levator ani M, inferior rectal n. and branches of the coccygeal plexus

*Posterior, thin, poorly developed part

Question 19

O, I, A, and N of Coccygeus m

Answer 19

O: ischial spine
I: Inferior sacrum and coccyx
A: Support pelvic viscera, flexes coccyx
N: nerve to the coccygeus (S4,5; branches of the coccygeal plexus)

Question 20

What type of fascia is obturator fascia?

Answer 20

Parietal membranous pelvic fascia

Question 21

O, I, A, and. N of obturator internus M

Answer 21

O: peelvic surfaces of the ilium and ischium and obturator membrane
I: greater trochanter of the femur
A: rotate thigh laterally, stabilize the femoral head in the acetabulum
N: nerve to the obturator internus m

Question 22

O, I, A, and N of piriformis M

Answer 22

O: pelvic surface sacral segemtns S2-S4, greater sciatic notch and sacrotuberous l
I: greater trochanter of the femur
A: rotate thigh laterally, abduct thigh, stabilize femoral head in acetabulum
N: nerve to piriformis m

Question 23

What are the superficial perineal muscles ?

Answer 23

Perineal body
Superficial perineal muscles
Ischiocavernosus m
Bulbospongiosus m