Growth And Development Of The Skull Flashcards
What are the two types of ossification
Intramemnranous
Endochondral
Describe intramembranous ossification
Mesenchymal model - mesenchyme differentiate into osteaoblasts which secrete osteoid these soon become osteocytes)
Bones ossify during fetal period
Brings at the centre and grows outwards
Descibe endochondral ossification
Cartilage model
Bone replaces cartilage starts at primary ossification centre
Mesenchymal lay down cartilage the artery impregnates this calcium
Middle is primary ossification centre
Ends are the secondary ossification centres
How are the flat bones of the skull formed
Membranous intramembranous ossification of the neurocranium
On the frontal and parietal bone
Disorder is hypervephlay
What kind of ossification forms the complex bones of the skull such as the sphenoid bone
Endochondral
Under tight genetic control
Lids order achondroplasia
What is hydrocephaly
When brain grows in cranial cavity Which is expansion rather than being inflated
The increase in the brain volume causes lift membrane bones of neurocranium form at sutures bones
A lot of fluid pushes brain sutures apart
WATER ON THE BRAIN
When is the skull growth rate determined
In utero
Why is the brain formed 25% before birth
For essential actions such as coughing suckling etc
Describe the shape of a neonate skull
Compromised skull size so not too hard for labour but large enough for the brain to develop essential qualities for life
What is the moulding of the skull like for a neonate skull
Wide sutures which pass over each ether to allow easy delivery
Feature fontanelles - soft spot - anteriofontanelle gap where there is a membrane no bone yet
What are some futures of the neonate skull overall
Wide coronal suture Anterior fontanelle Parental and frontal eminences Frontal suture Posters lateral fontanelles Wide squamousal suture Small jaws
What is the ratio of skull to face in a neonate
8:1
What is the ratio of skull to face for an adult
2.5:1
What are some qualities of the adult skull
Lightness - so can support the brain optimised by diploe, and paranasal sinuses
Strength - protection of brain, special senses, near spherical to get the max vola nd strength, suture joints is the crack stoppers, buttresses dissipate the forces with a crumple zone
Keep airways open
Warm and humidfy air in through the nose
What is diploe
Sandwich
Outer compact bone, light cancellous inner compact bone
Confers lightness of the skull
Filled with spaces
Of marrow
Commonly get depressed fractures as they absorb energy
