The Pelvis and Fetal Skull

Question 1

What are the 4 different types of pelvis?

Answer 1

1. Anthropoid (25%)
2. Android (20%)
3. Gynaecoid (50%)
4. Platypelloid (5%)

Question 2

What is the optimal fetal dimension and what is moulding?

Answer 2

Fetal dimension: Subboccipito-bregmatic (SOB)
Moulding is a protective mechanism that prevents the compression of the fetal brain allowing the fetal skull to change in shape to adapt to the birth canal.

Question 3

What does the pelvis floor do and how does the structure of the pelvic floor allow this?

Answer 3

The pelvic floor makes the baby rotate.
Its composed primarily of muscle fibres and soft tissue suspended within the outlet of the pelvis, forming a dome-like sheet of tissue.

Question 4

What 3 things does the Levator-ani muscle do?

Answer 4

1. Maintains constant tone (except during voiding and defaecation)
2. Has the ability to contract quickly at the time of acute stress.
3. Distend’s to allow the passage of the fetus and contract to resume normal functioning.

Question 5

What are the 4 types of movements of the pelvis?

Answer 5

1. Extrinsic (whole pelvis)
2. Intrinsic (pelvic bones)
3. Nutation (closes pelvic brim, opens outlet)
4. Counter-Nutation (opens pelvic-brim, closes outlet)