Foetal Skull Flashcards
Name the bones of the foetal skull
- 2 frontal bones
- 2 parietal bones
- 2 temporal bones
- 1 occipital bone
What parts makes up the foetal skull?
- Vault (main bones)
- Base
- Face
What is the name of the brow region?
Sinciput
What are sutures?
Soft areas of fibrous tissue where ossification is not complete
Name the sutures of the foetal skull
- Frontal (between frontal bones)
- Coronal (between the frontal and parietal bones)
- Sagittal (between parietal bones)
- Lamboidal (between the occipital and parietal bones)
What is a fontanelle?
A membranous non-ossified area where sutures meet
What are the names of the fontanelles?
Anterior fontanelle (bregma) Posterior fontanelle (lambda)
Describe the bregma
- Diamond shaped (4 attachment points)
- Closes at 18 months
- Larger than the lambda
If the bregma is felt on VE, what position is the baby likely to be in?
Direct OP with deflexed head
Describe the lambda
- Triangular (3 attachment points)
- Closes at 6 weeks
- Smaller than the bregma
If the lambda is felt on VE, what position is the baby likely to be in?
OA with a flexed head
What are the diameters of the skull?
- Suboccipitobregmatic
- Suboccipitofrontal
- Occipitofrontal
- Mentovertical
- Submentovertical
- Submentobregmatic
- Biparietal
- Bisacromial
- Bitrochanteric
Describe the suboccipitobregmatic diameter
- Below the occipital bone to the centre of the bregma
- 9.5cm
Describe the suboccipitofrontal diameter
- Below the occipital bone to the centre of the frontal suture
- 10cm
Describe the occipitofrontal diameter
- Occipital protuberance to the centre of the frontal suture
- 11.5cm
Describe the mentovertical diameter
- From the chin straight upwards to the highest point on the vertex
- 13.5cm
Describe the submentovertical diameter
- From the point where the chin meets the neck straight upwards to the highest point of the vertex
- 11.5cm
Describe the submentobregmatic diameter
- From the point where the chin meets the neck to the centre of the bregma
- 9.5cm
Describe the biparietal diameter
- Stretches between the parietal eminences
- 9.5cm
Describe the bisacromial diameter
- Stretches between the 2 shoulder blades
- 12cm
Describe the bitrochanteric diameter
- Stretches between the greater trochanters of the femurs
- 10cm
Describe a vertex presentation
- When head is well flexed, suboccipitobregmatic and biparietal diameters present
- When head is deflexed, occipitofrontal and biparietal diameters present
Describe a face presentation
Head is extended and the submentobregmatic and bitemporal diameters present
Describe a brow presentation
Head is partially extended and the mentovertical and bitemporal diameters present
