Pelvis and Perineum Osteology and boundaries

Question 1

3 main bones in pelvis

4 main joints in pelvis

Answer 1

Ilium
Ischium
Pubis

Sacroiliac joint
Lumbosacral joint
Coccygeus joint
Pubis symphysis

Question 2

What direction does the pelvic girdle sit in the anatomical position

Answer 2

Anterior posteriorly

Question 3

Angle of inclination of pelvic inlet and pelvic outlet

Answer 3

Pelvic inlet 50-60C

Pelvic outlet 10-15C

Question 4

Structures of the pelvis from the lateral side

Answer 4

Anterior superior iliac spine
Triradiate cartilage and acetabulum
Pubic crest
Ischium

Ossification at joint at cartilage finishes at puberty

Question 5

Ligaments at the pelvis

Answer 5

Pelvic outlet connected to ligaments

Creates flexibility needed for the baby’s head to come out

Question 6

Shape of the pelvic inlet and outlet

Answer 6

Pelvic inlet roughly circular

Pelvic outlet roughly butterfly shaped

Question 7

Subpubic angles of the male and female pelvis

Answer 7

Male, subpubic angle <90

Female, subpubic angle >90

Question 8

Anteropsterior diameter of pelvic inlet and bispinous diameter and the importance of these diameters

Answer 8

Narrowest transverse diameter between ischial spines

Narrowest ante posterior diameter between obstetric conjugate between sacrum and pubic symphysis

If diameter too narrow, cannot deliver vaginally

Question 9

Types of pelvis

Answer 9

Android (longer AP)
Gynecoid (longer transverse)
Anthropoid
Platypelloid (outlet too small for baby)

Question 10

Pelvic organs and pouches in males and females

Answer 10

Males
Rectovesicular pouch

Females
Uterovesical pouch and Rectouterine pouch

Sites where infection is likely

Question 11

What structures in the pelvis are extraperitoneal

Answer 11

Urinary bladder

Question 12

Pelvic floor/diaphragm function

Answer 12

Supports pelvic organs and separates pelvic cavity from perineum
If pelvic floor is incompetent, can lead to incontinence, prolapse

Question 13

Muscles that make up the pelvis diaphragm

Answer 13

Levator ani (puborectalis, pubococcygeus, iliococcyggeous)
Coccygeus
Piriformis

Question 14

Triangles found in the pelvis

Answer 14

Urogenital triangle, (pubic symphysis, ischial tuberosity) faces AP

Anal triangle, (Ischial tuberosity, coccyx) faces SI

Question 15

Structure of the perineum

Answer 15

Ischiocavernosus on either side of urogenital triangle

Transverse perineal muscle with perineal body in the middle of this muscle

Bulbospongiousis between ischiocarvernosus
In females, surrounds vagina and urethra

Perineal body behind these muscles

Question 16

Episiotomy

Answer 16

Diagonal cut to prevent damage to perineal body during parturition

Question 17

Structure of perineum in layers from the outside in

Answer 17

Skin
Perineal muscle
Perineal membrane
Inferior diaphragm

Question 18

Where is the superficial and deep pouch

Answer 18

Superficial pouch, between skin and perineal membrane. Perineal muscles in pouch here

Deep pouch, behind perineal membrane

Question 19

Importance of the perineal pouches in trauma

Answer 19

Any fluid that accummulates in the superficial pouch will rise up into the abdomen, can be seen in the skin

Any fluid accumulating in the deep pouch can only be detected by scans

Question 20

Structure of deep perineal pouch in males

Answer 20

Perineal membrane wraps around deep pouch
Transverse perineal muscle wrapped around by perineal membrane

External urethral sphincter around urethra