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Flashcards in Growth And Development Of The Skull Deck (24):
1

What are the two types of ossification of the skull

Intramembranous - mesenchymal cells differentiate into osteaoblasts which secrete osteoid and cells called osteocytes form when trapped ossify during fetal period and starts at the centre and ossifies outwards

Endochondral - cartilage model artery through bone impregnates Cartilage with calcium primary and secondary centres

2

Where does each of the ossifications of the skull occur

Intramembranous ossification
- flat bones of skull
- parietal frontal
-Easily modified by environmental factors (hydrocephaly)

Endochondral ossification
- bones of the base of the skull
- more complex
- ethmoid and sphenoid
-Tight genetic control
- deformity is achondroplasia

3

Which sinus is absent at birth

Frontal sinus

4

What is hydrocephaly

Water on the brain
Brain grows in cav like balloon
Increasing brain volume = lifts membrane bones apart applying tension to the sutures

5

When is the cranial growth depicted

Dictated in-utero

6

Why is the brain ~25% formed at birth

To perform essential protective qualities for life such as suckling and coughing

7

What is special about fontanelles

Soft spots which is a gap where no bone has been developed yet
Anteriofontanelle
Can move and moulded during giving birth to help mother

8

What does the neonate minimal development have as a positive

Non essential parts are not fully formed so the neonate has small jaws and nose
This all has to do with the compromise of giving birth compromise

9

Where are both of the fontanelles and when does one close

Anterior and posterior, posterolateral fontanelle
Anterior closes at ~18 months

10

What is an eminence

Bone that protrudes slightly frontal and parietal
Converted of ossification

11

How can a baby not hold up its head

Structures such as mastoid process not fully developed so postural muscles such as scm cannot support neck as muscle is unsupported

12

What is the difference between the pelvic inlet and outlet

Inlet - transverse diameter > AP diameter
Outlet - transverse diameter

13

What's it the ratio of skull:face for a neonate and adult

Neonate - 8:1
Adult - 2.5:1

14

What influences the growth of the jaw

The development and eruption of teeth
Wisdoms don't

15

How are various processes of the skull formed

As muscles attach to bones pull on them developing processes

16

What kind of hormones influence skull growth

Sex hormones
Males - bulkier stronger skull
Female - tensile and delicate

17

What does the primary cartilaginous joint allow

Synchondroses
In base of skull allow face to be carried forward as it grows

18

What are the two synchondroses of the skull

Spheno-ethmoidal synchondrosis close at 6
Spheno-occipital activated at birth and close at 25

19

How is the adult skull light

Lightness optimised by
Diploe
Orbits
Cavities
Paranasal sinuses

20

What are the paranasal sinuses

Air filled spaces
Maxilla
Sphenoid
Frontal
Ethmoid

21

How is the adult skull strong

Near spherical shape
Suture joints crack stoppers
Has a crumple zone and incorps Le fort fractures and buttress syst

22

What is diploe

Sandwich
Has outer and inner compact bone
And light cancellous centre which is the diploe

This is light and strong
Many holes filled with fatty marrow
Shock absorber

23

What are the endentulous changes

Alveolar processes resorb from the maxilla and mandible due to loss of teeth

24

What are the three conformational changes of the skull

Neonate - before birth and of small infant
Adult - usual
Old age - may end up Edentulous