Flashcards in Foetal Skull Deck (47)
Describe the skull
- Consists of 29 bones
- Ovoid shaped
- Consists of vault, base and face
What are the skull bones divided into?
- 2 frontal
- 2 parietal
- 2 temporal
- 1 occipital
What is the vault?
Dome-shaped part between the orbital ridges and the nape of the neck
Describe the occipital bone
- Lies at the back of the head
- Ossification centre = occipital protuberance
Describe the parietal bones
- Lie on either side of the skull
- Ossification centres = parietal eminences
Describe the frontal bones
- Form the forehead and sinciput
- Ossification centres = frontal eminences
What is the base?
Firmly united bone protecting the vital centres of the medulla oblongata
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
What are the 4 regions of the foetal skull?
1. Forehead/ Sinciput region (brow)
Describe the forehead/ sinciput region
Extends from the anterior fontanelle and the coronal suture to the orbital ridges
Describe the vertex
Bounded by the posterior fontanelle, the 2 parietal eminences and the anterior fontanelle
- Vertex positing = head first
Describe the occiput
- Lies between the foramen magnum and posterior fontanelle
- The part below the occipital protuberance is known as the sub-occipital region
Name 3 landmarks
1. Occipital protuberance
2. Mentum (chin)
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
What is ossification?
The hardening of the bones of the vault from the ossification centre outwards
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
What is a fontanelle?
A membranous non-ossified area where 2 or more sutures meet
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
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
What is another name for the anterior fontanelle?
Describe the posterior fontanelle
- Smaller than the anterior fontanelle
- Formed by junction of lamboidal and sagittal sutures
- Closes at 6 weeks
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
What is another name for the posterior fontanelle?
What are the 9 diameters of the foetal skull?
Describe the suboccipitobregmatic diameter
- Below the occipital bone to the centre of the anterior fontanelle
Describe the suboccipitfrontal diameter
- Below the occipital bone to the centre of the frontal bone/ suture
Describe the occipitofrontal diameter
- The occipital protuberance to the glabella (frontal bone)
Describe the mentovertical diameter
- From the point of the chin straight upwards to the highest point on the vertex
Describe the submentovertical diameter
- From the point where the chin meets the neck, straight upwards to the highest point on the vertex