Session 4 - The pelvis

Question 1

What are the two main muscles of male perineum?

Answer 1

Bulbospongiosus

Ischiocavernosus

Question 2

What does bulbospongiosus do?

Answer 2

Helps to expel last drops of urine and maintain erections

Question 3

What does ischiocavernosus do?

Answer 3

Compresses veins, helping ot maintain erections

Question 4

What are the three parts of the hip bone?

Answer 4

Ilium
Ischium
Pubis

Question 5

What is the pelvic girdle made up of?

Answer 5

Sacrum

Right and left hip bones

Question 6

Where do the hip bones articulate with the sacrum?

Answer 6

Sacroilliac joint

Question 7

Where do the hip bones articulate with each other?

Answer 7

Pubic symphyy

Question 8

What is a gynecoid pelvis?

Answer 8

o	Round inlet
o	Straight side walls
o	Ischial spines not too prominent
o	Well-rounded greater sciatic notch
o	Well-curved sacrum (to fit with foetal head)
o	Sub-pubic arch > 900

Question 9

Give five differences between male and female pelvi

Answer 9

General structure
- Male thick and heavy
- Female - Thin and light 
Pubic arch and subpubic angle
- Male - Narrow (80) 
Obturator foramen 
- Male, round
- Female, oval
Acetabulum
- Male - large
Female - Small
Greater sciatic notch 
- Male - Narrow 
- Female - > 90*

Question 10

What is the pelvic inlet formed by?

Answer 10

o Promontory and ala of the sacrum posteriorly
 Superior surface of its lateral part, adjacent to the body of the sacrum
o Right and left linea terminalis anteriorly
 Arcuate line on the inner surface of the ilium
 Pectineal line and pubic crest

Question 11

What are three measurements which must be made in a clinical assesment of the pelvic inlet?

Answer 11

Anatomic conjugate
Obstetric conjugate
Diagonal conjugate

Question 12

What is the anatomic conjugate?

Answer 12

 Measured from the sacral promontory to the superior border of the pubic symphysis

Question 13

What is the obstetric conjugate?

Answer 13

 Measured from sacral promontory to the midpoint of the pubic symphysis.
 Minimum diameter of the canal, as this is where the pubic bone is the thickest

Question 14

What is the diagonal conjugate?

Answer 14

 Measured from sacral promontory to the inferior border of the pubic symphysis

Question 15

What is the pelvic outlet formed by?

Answer 15

o	Pubic arch anteriorly
o	Ischial tuberosities laterally
o	Inferior margin of the sacrotuberous ligament posterolaterally
o	Sacrospinous ligament also present 
o	Tip of the coccyx posteriorly

Question 16

What is the pelvic inlet made up of posteriorly?

Answer 16

Sacrotuberous ligament

Question 17

What happens to the sacrotuberous ligament during child birth?

Answer 17

Progesterone works to soften the ligament to increase the size of the pelvic outlet to aid childbirth

Question 18

What is the greater pelvis bounded by?

Answer 18

o Superior to the pelvic inlet
o Bounded by the iliac alae posterolaterally
o Bounded by the anterosuperior aspect of the S1 vertebra posteriorly
o Occupied by abdominal viscera (E.g. the ileum and sigmoid colon)

Question 19

What is the lesser pelvis bounded by?

Answer 19

o The bony canal, which is solid and immovable, between the pelvic inlet and outlet
o Bounded by the pelvic surfaces of the hip bones, sacrum and coccyx
The lesser pelvis is of major obstetrical and gynaecological significance.