Development of the skull Flashcards
What is a synchondrosis
A primary cartilaginous joint –Mainly found in the developing skeleton (e.g. growth plates).
Adult example – between first rib and sternum. Hyaline cartilage
between the two bone surfaces with very little movement permitted.
Where would you expect to see the Spheno-occipital synchondrosis?
Between the sphenoid and occipital bones – allows growth in the base of the skull.
What is an ossification centre
An ossification centre is the starting point for bone growth. Some bones in the skull develop from several ossification centres, which later fuse into a single bone.
The first ossification centre to appear is the primary ossification centre.
How many ossification centres does the occipital bone develop from
Usually 6 - part 3,4 fused by birth
What is a fontanelle and why are these important structures in the developing skull?
Membranous areas “soft spots” between bones of the calvarium (neurocranium). Allow for compression and overlap of bones during
birthing - head can appear slightly distorted for several days following birth.
Also important for continued rapid growth of brain after baby is born.
How many fontanelles are there and when does each close
1x Anterior, 1x Posterior, 2x Mastoid (posterolateral), 2x Sphenoidal (anterolateral)
Approx. Closure Pattern (all postpartum)
Between 1-3 months - Posterior Fontanelle
By around 6 months - Sphenoidal (anterolateral) Fontanelle
Between 6-18 months - Mastoid (posterolateral) Fontanelle
By around 2 years - Anterior Fontanelle
What is the lambida
Were the sagittal suture meets the lambdoid suture
What is the bregma
Where the sagittal suture meets the coronal suture
Why are the proportions in a fetal skull different to an adult skull
Brain development most important before birth BUT skull needs to be small enough for passage through pelvis during birth. Face grows as dentition develop and in response to muscles of mastication – teeth not required at
birth for feeding.
What causes the change from a more obtuse angle of the mandible in a fetal skull to an adult mandible
Forward and downward growth of mandible to accommodate developing dentition
When is the tympanic ring formed
Around 3rd month in utero
How do male and female mandibles differ
Females angle of the mandible more obtuse
Male mandibles more square around 90 degree angle
