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Scientific Basis of Midwifery > Foetal Skull > Flashcards

Flashcards in Foetal Skull Deck (47)
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1

Describe the skull

- Consists of 29 bones
- Ovoid shaped
- Consists of vault, base and face

2

What are the skull bones divided into?

- Vault
- 2 frontal
- 2 parietal
- 2 temporal
- 1 occipital

3

What is the vault?

Dome-shaped part between the orbital ridges and the nape of the neck

4

Describe the occipital bone

- Lies at the back of the head
- Ossification centre = occipital protuberance

5

Describe the parietal bones

- Lie on either side of the skull
- Ossification centres = parietal eminences

6

Describe the frontal bones

- Form the forehead and sinciput
- Ossification centres = frontal eminences

7

What is the base?

Firmly united bone protecting the vital centres of the medulla oblongata

8

Describe the face

- 14 small bones
- Firmly united and non-compressible
- Extends from orbital ridges to neck
- The point between the eyebrows in known as the glabella

9

What are the 4 regions of the foetal skull?

1. Forehead/ Sinciput region (brow)
2. Vertex
3. Occiput
4. Face

10

Describe the forehead/ sinciput region

Extends from the anterior fontanelle and the coronal suture to the orbital ridges

11

Describe the vertex

Bounded by the posterior fontanelle, the 2 parietal eminences and the anterior fontanelle
- Vertex positing = head first

12

Describe the occiput

- Lies between the foramen magnum and posterior fontanelle
- The part below the occipital protuberance is known as the sub-occipital region

13

Name 3 landmarks

1. Occipital protuberance
2. Mentum (chin)
3. Glabella

14

What is a suture?

- The cranial joints formed when 2 bones meet
- Soft, fibrous tissue where ossification is not complete
- Allows moulding during labour and birth and expansion of brain development

15

What is ossification?

The hardening of the bones of the vault from the ossification centre outwards

16

What are the 4 sutures called?

1. Frontal - between 2 halves of the frontal bone
2. Sagittal - between 2 parietal bones
3. Lamboidal - separates occipital bone and 2 parietal bones
4. Coronal - separates front bones from parietal bones

17

What is a fontanelle?

A membranous non-ossified area where 2 or more sutures meet

18

Describe the anterior fontanelle

- Diamond/kite shaped
- Formed by junction of sagittal, coronal and frontal sutures
- Larger than the posterior fontanelle
- Closes at 18 months of age

19

What should the anterior fontanelle feel like during a VE?

- 4 sutures felt emanating from the fontanelle
- Demonstrates de-flexed head
- Alerts practitioners to larger diameter coming through pelvis
- Indicates direct occipital position

20

What is another name for the anterior fontanelle?

Bregma

21

Describe the posterior fontanelle

- Triangular
- Smaller than the anterior fontanelle
- Formed by junction of lamboidal and sagittal sutures
- Closes at 6 weeks

22

What should the posterior fontanelle feel like during a VE?

- 3 sutures felt emanating from fontanelle
- Well-flexed head position
- Smaller diameter presenting
- Indicated occipitoanterior position

23

What is another name for the posterior fontanelle?

Lambda

24

What are the 9 diameters of the foetal skull?

1. Suboccipitobregmatic
2. Suboccipitofrontal
3. Occipitofrontal
4. Mentovertical
5. Submentovertical
6. Submentobregmatic
7. Biparietal
8. Bisacromial
9. Bitrochanteric

25

Describe the suboccipitobregmatic diameter

- Below the occipital bone to the centre of the anterior fontanelle
- 9.5cm

26

Describe the suboccipitfrontal diameter

- Below the occipital bone to the centre of the frontal bone/ suture
- 10cm

27

Describe the occipitofrontal diameter

- The occipital protuberance to the glabella (frontal bone)
- 11.5cm

28

Describe the mentovertical diameter

- From the point of the chin straight upwards to the highest point on the vertex
- 13.5cm

29

Describe the submentovertical diameter

- From the point where the chin meets the neck, straight upwards to the highest point on the vertex
- 11.5cm

30

Describe the submentobregmatic diameter

- From the point where the chin meets the neck to the centre of the bregma
- 9.5cm