The Fetal Skull

Question 1

What happens to early fetal life to the fetal skull?

Answer 1

Bones of the skull are initially membrane and is then replaced by bone from central points of ossification. This process develops until adulthood to allow the brain to develop and grow.

Question 2

What happens during labour to the fetal skull?

Answer 2

The fetal skull is made up of separate bones which can move independently to allow the fetal skull to accommodate to the diameters of the maternal pelvis during labour.

Question 3

What are the regions of the fetal skull that are important in understanding with the birthing process?

Answer 3

• Bones covering the cerebral hemisphere
• Sutured dividing these bones
• Two fontanelles

Question 4

What is the fetal skull made up of

Answer 4

• THE VAULT: occipital bone, frontal bone, parietal bone and temporal bone.
• THE FACE
• THE BASE
  
  • both fused at term to minimise movement.

Question 5

Where are the centre points of ossification?

Answer 5

• they are identified at the vault
• Parietal eminence
• Occipital protuberance
• Frontal eminence

Question 6

What are the landmarks of the fetal skull?

Answer 6

The sinciput: FOREHEAD
The mentum: CHIN
The bregma: ANTERIOR FONTANELLE
The lambda: POSTERIOR FONTANELLE
The vertex: THE HIGHEST POINT IF THE FETAL SKULL
The occiput: AREA OVER THE OCCIPITAL BONE
The glabella: THE BRIDGE OF THE NOSE

Question 7

What are the sutures?

Answer 7

-Where fetal skull bones attach to each other
-Composed of soft fibrous tissue
-Allows movement and overlapping
FRONTAL SUTURE: joins the frontal bone
SAGITTAL SUTURE: joins the two parietal bone
LABOIDAL SUTURE: joins the parietal bone with the occipital bone.

Question 8

What are the fontanelles of the fetal skull?

Answer 8

Where three or more sutures meet, a fontanelle (soft fibrous tissue) is formed:
The bregma → located where the two frontal and the two parietal bones meet. Kite shaped. Ossify at 18 months of childhood.
The lambda → located where the parietal bones meets the occipital bone. Closes 6 weeks after birth.

Question 9

Why is it important for the midwife to know the diameters of the fetal skull?

Answer 9

It is important for the midwife to know the diameters of the pelvis and the fetal skull to implicate the presentation and position of the fetus through the birth canal.

Question 10

What are the longitudinal diameters of the fetal skull?

Answer 10

Longitudinal diameters: during delivery the attitude of the fetal skull head determines which of these diameters is presenting
VERTEX--> SOB--> 9.5
OCCIPITOPOSTERIOR-->SOF-->10
CEPHALIC-->OF-->11.5
BROW-->MV-->13.5
FACE-->SMV-->11
FACE-->SMB-->9.5

Question 11

What are the transvere diameters of the fetal skull?

Answer 11

• biparietal diameter: 9.5cm

- bitemporal diameter: 8cm