The Fetal Skull

Question 1

What are the names of the two fontanelles on the front and back of the fetal head?

Answer 1

Front- anterior fontanelle also known as the Bregma.

Back - posterior fontanelle

Question 2

There are three main bones which make up the fetal skull, what are there names?

Answer 2

Frontal bone, parietal bone, occipital bone.

Question 3

The fetal skull can be split into three sections. What are these called?

Answer 3

Face (glabella to chin)
Base (chin to occiput)
Vault (occiput to glabella)

Question 4

What is a suture? What 2 things does a suture enable?

Answer 4

Soft fibrous tissues that bond together the bones of the skull. They enable moulding of the head during labour and expansion of the brain during childhood.

Question 5

What are the names of the 4 sutures present on the fetal skull?

Answer 5

Frontal suture (vertical suture between two halves of the frontal bone) 
Coronal suture (horizontal suture between frontal bone and parietal bone) 
Sagittal suture (vertical suture between two halves of the parietal bone) 
Lambdoidal suture (horizontal suture between parietal bone and occipital bone)

Question 6

What is a fontanelle?

Answer 6

A membranous area of the skull where 3 or more sutures meet.

Question 7

SOF is a fetal skull diameter. What does it stand for? Which two points does it cross? What is the measurement of the diameter?

Answer 7

Suboccipitofrontal.
Crosses below the occiput and the frontal suture.
Average diameter is 10cm.

Question 8

SMB is a fetal skull diameter. What does it stand for? Which two points does it cross? What is the measurement of the diameter?

Answer 8

Submentobregmatic.
Crosses the chin and the anterior fontanelle.
Average diameter is 9.5cm.

Question 9

SOB is a fetal skull diameter. What does it stand for? Which two points does it cross? What is the measurement of the diameter?

Answer 9

Suboccipitobregmatic.
Crosses below the occiput and the anterior fontanelle.
Average diameter is 9.5cm.

Question 10

MV is a fetal skull diameter. What does it stand for? Which two points does it cross? What is the measurement of the diameter?

Answer 10

Mentovertical.
Crosses the chin and the vertex.
Average diameter is 13.5cm.

Question 11

SMV is a fetal skull diameter. What does it stand for? Which two points does it cross? What is the measurement of the diameter?

Answer 11

Submentovertical.
Crosses below the chin and the highest point of the vertex.
Average diameter is 11cm.

Question 12

OF is a fetal skull diameter. What does it stand for? Which two points does it cross? What is the measurement of the diameter?

Answer 12

Occipitofrontal.
Crosses the occiput and the bridge of the nose (glabella).
Average diameter is 11.5cm.

Question 13

What 4 lobes make up the fetal brain? What is the 5 element called?

Answer 13

• Frontal lobe
• Temporal lobe
• Occipital lobe
• Parietal lobe

-Cerebellum

Question 14

What is the role of the corpus callosum?

Answer 14

The corpus callosum links the right and left hemispheres of the brain. It transfers information between the two.

Question 15

What 5 layers make up the fetal SCALP?

Answer 15

1. Skin
2. Subcutaneous tissue
3. Galea aponeurotica
4. Loose connective tissues
5. Periosteum

Question 16

There are two main partitions within the fetal brain. What are these called and where do they occur?

Answer 16

Falx ceribri- occurs between the right and left hemispheres of the brain.
Tentorium cerebelli- separates the cerebrum from the cerebellum.

Question 17

What is Caput succedaneum? What is is caused by? How long does it last?

Answer 17

A fetal skull injury where there is swelling in the scalp tissue. Caused by excess pressure on the fetal scalp from the cervix. Caput succedaneum crosses the sutures and typically goes down within 48 hours.

Question 18

What is Cephalohaematoma? What is is caused by? How long does it last?

Answer 18

Bleeding between the periosteum and the fetal skull bone. Can be caused by trauma during birth, prolonged labour or instrumental delivery. Cephalohaematoma does not cross a suture line and persists for weeks.

Question 19

What is moulding?

Answer 19

During labour, the fetal skull has the ability to flex to enhance its passage through the birth canal.