Osteology of the Pelvis

Question 1

What is the pelvis made up of?

Answer 1

4 bones

Question 2

What are the categories of bones in the pelvis?

Answer 2

• Innominate bones
• Sacrum
• Coccyx

Question 3

What do the 2 innominate bones of the pelvis form?

Answer 3

The iliac crest

Question 4

Where do the 2 innominate bones of the pelvis join?

Answer 4

At the sacrum and the coccyx

Question 5

What is formed when the two innominate bones of the pelvis join at the sacrum and the coccyx?

Answer 5

The pelvic girdle

Question 6

What does the linea terminalis define?

Answer 6

Where you enter the pelvis from the faux pelvis

Question 7

What does the linea terminalis consist of?

Answer 7

• Arcuate line
• Pectineal line
• Pubic crest

Question 8

What osteological features do the innominate bones of the pelvis have?

Answer 8

• Ischial spine
• Ischial tuberosity

Question 9

What does the ischial spine seperate into?

Answer 9

The greater and lesser sciatic notches

Question 10

What is the function of the ischial tuberosity?

Answer 10

It is the part of the pelvic girdle on which you sit

Question 11

What is the gynacological importance of the sacrum?

Answer 11

The anterior superior edge of the first sacral vertebrae is very prominent, and projects into the pelvic cavity, which can be a problem when giving birth

Question 12

What is the ‘false pelvis’?

Answer 12

The greater pelvis, superior to the linea terminalis

Question 13

Does the false pelvis have any gynacological relevance?

Answer 13

No

Question 14

What is the ‘true pelvis’?

Answer 14

The lesser pelvis, a bony canal that is solid and immobile

Question 15

What is a ‘good’ pelvis for childbirth termed?

Answer 15

A gynacoid pelvis

Question 16

What are the features of a gyancoid pelvis?

Answer 16

• Round inlet
• Straight side walls
• Ischial spines not too prominent
• Well rounded sciatic notch
  Well-curved sacrum
• Sub-pubic arch greater than 90 degrees

Question 17

What are the ‘pelvic planes’ of the pelvis?

Answer 17

• Pelvic inlet
• Plane of greater diameter
• Plane of least diameter
• Pelvic outlet

Question 18

What does a clinical assessment of the pelvis consist of?

Answer 18

• Measuring the anteroposterior diameter of the pelvic inlet
• Assessing the mid-pelvis
• Assessing the pelvic outlet

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Question 19

How is the obstetric conjugate measured?

Answer 19

From the sacral promontory to the midpoint of the pubis symphysis

Question 20

What does the obstetric conjugate define?

Answer 20

The minimum AP diameter

Question 21

What is the problem with the measurement of the anteroposterior diameter?

Answer 21

It cannot be palpated, so must make an approximation using the diagonal conjugate

Question 22

How is the diagonal conjugate measured?

Answer 22

From the sacral promontory to the inferior border of the pubic symphysis

Question 23

How does the diagonal conjugate measurement compare to the obstetric conjugate?

Answer 23

It is slightly smaller

Question 24

How is the mid-pelvis assessed?

Answer 24

• Check for straight side walls
• Bispinous diameter

Question 25

What is meant by the bispinous diameter?

Answer 25

Distance between the ischial spines

Question 26

How is the pelvic outlet assessed?

Answer 26

• Infrapubic angle
• Distance bewteen the ischial tuberosity

Question 27

How are the ligaments of the pelvis involved in delivery?

Answer 27

They provide some ‘give’ in delivery

Question 28

What are the ligaments of the pelvis?

Answer 28

• Sacrospinous ligament
• Sacrotuberous ligament

Question 29

Where does the sacrospinous ligament run?

Answer 29

Sacrum to ischial spine

Question 30

Where does the sacrotuberous ligament run?

Answer 30

Sacrum to ischial tuberosity

Question 31

What happens to the ligaments during pregnancy?

Answer 31

Hormones serve to soften the ligament, to make them more stretchy and soften joints