Pelvis And Perineum

Question 1

The pelvis as a cavity is divided into

Answer 1

• greater pelvis/false pelvis (in abdominal cavity)
• lesser pelvis/true pelvis
• separated by pelvic inlet (pelvic brim/superior pelvic aperture)

Question 2

What are the boundaries of the pelvic brim (pelvic inlet)

Answer 2

• promontory (of the sacrum)
• margin of ala (ala of sacrum)
• arcuate line (of the ilium)
• pectin pubis
• pubic crest
• symphysis pubis

Question 3

What are the boundaries of the pelvic outlet (diamond shape)

Answer 3

• subpubic angle/symphysis pubis (anteriorly)
• ischiopubic rami/pubic arch (anterolateral)
• ischial tuberosities (anterolateral)
• sacrotuberous ligaments (posterolateral)
• tip of the coccyx (posteriorly)

Question 4

Know the locations of the pelvic wall muscles

Answer 4

***piriformis, obturator internus, coccygeus, obturator canal

Question 5

What are the muscles of the pelvic floor

Answer 5

• levator ani
  1) puborectalis (most medial loop)
  2) pubococygeus (immediate second loop)
  3) illiococcygeus (most lateral of the 3).
• coccygenus

Question 6

What structures make up the urogenital hiatus

Answer 6

• urethra (males)

- urethra and vagina (female)

Question 7

What are the functions of the levator ani muscles

Answer 7

1) “continance enforcers”
- medial fibers are lateral compressors to visceral canals
- puborectalis helps create rectoanal angle and enforce anal sphincter
2) support pelvic visceral
3) contractions increase intra-abdominal pressure during expulsive activities (urination, defecation, delivery)

Question 8

Perineum

Answer 8

The perineum is the area inferior to levator ani (roof) and between the two thinghs

Question 9

Boundaries of the perineum

Answer 9

1) inferior border of the pubic symphysis/subpubic angle (anterior)
2) right and left ischial rami/tuberosities (anterolateral)
3) right and left sacrotuberous ligaments (posterolateral)
4) tip of coccyx (posterior)

Question 10

What are the divisions of the perineum

Answer 10

• divided by imaginary line between ischial tuberosities into two triangles
• urogenital triangle (anterior)
• anal triangle (posterior)

Question 11

Urogenital/anterior triangle contains:

Answer 11

1) urethra
2) root of penis in male/root of clitoris in female
3) bulb of the vestibule and vaginal orifice in female

Question 12

Posterior/anal triangle contains:

Answer 12

1) anal canal surrounded by 2 ischioanal fossae in males and females

Question 13

Urogenital triangle/anterior triangle of perineum

Answer 13

• located between the pubic arch and imaginary line connecting two ischial tuberosities
• roof: levator ani muscle
• pierced by: urethra, vagina, & contains roots of external genitalia
• divided into deep & superficial spaces(pouches)

Question 14

Know diagram of boundaries of superficial perineal pouch and deep perineal space (slide 22)

Answer 14

-Roof: perineal membrane
–>(separates superficial perineal pouch from deep perineal space)
Floor: colles fascia, superficial fat, skin
–> (going from innermost to outermost)

Question 15

What are the contents of the superficial perineal pouch

Answer 15

1) urethra
2) vaginal orifice
3) root of the external genitalia (root of penis and clitoris) and related muscles
- bulb of penis or vestibule (bulbospongiosus)
- crus of the penis or clitoris (ischocavernosus)
- superficial transverse perineal muscle
4) greater vestibular glands (in female)

Question 16

Boundaries of the deep perineal pouch

Answer 16

• superior fascia of the urogenital diaphragm (above)

- perineal membrane (below)

Question 17

What are the contents of the deep perineal pouch

Answer 17

• males (urethra, external urethral sphincter)

- females (urethra, external urethral sphincter, vagina)

Question 18

Blood supply of the perineum

Answer 18

• internal pudendal artery (major supply)
• it is a branch of anterior part of internal iliac artery
• Branches: inferior rectal artery, artery of eh bulb of penis/vestibule, urethral artery (male only), deep artery of penis/clitoris, dorsal artery of penis/clitoris

Question 19

Anal triangle

Answer 19

The anal triangle is the posterior triangular area of the perineum between the two sacrotuberous ligaments posteriorly & imaginary line between the ischial tuberosities

Question 20

What are the contents of the anal triangle

Answer 20

• anal canal and its sphincter

- right and left ischioanal fossae

Question 21

What are the walls of the ischioanal fossa

Answer 21

1) levator ani (medial wall)
2) oboturator internus, ischium, sacrotuberous ligament (lateral wall)
3) sacrotuberous ligament and gluteus maximus (posterior wall)
4) posterior border of urogenital diaphragm (anterior wall)

Question 22

What are the contents of the ischioanal fossa

Answer 22

1) fats

2) inferior rectal nerve and vessels

Question 23

Anal canal

Answer 23

• major structure of the anal triangle
• begins where the rectal ampulla suddenly narrows
• length is on average 4cm in adults with anterior wall slightly shorter than posterior wall

Question 24

What are the boundaries of the anal canal

Answer 24

1) posteriorly: anococcyheal raphe, separates canal form tip of coccyx
2) anteriorly: perineal body, separates canal from membranous urethra & penile bulb in male, and vagina in female
3) laterally: ischioanal or rectal fossae

Question 25

Internal anal sphincter

Answer 25

-smooth muscle, derived from the circular muscle layer of anal canal

Question 26

External anal sphincter

Answer 26

-skeletal muscle, supplied by inferior rectal nerve