Growth And Development Of The Skull

Question 1

What are the two types of ossification of the skull

Answer 1

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

Question 2

Where does each of the ossifications of the skull occur

Answer 2

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

Question 3

Which sinus is absent at birth

Answer 3

Frontal sinus

Question 4

What is hydrocephaly

Answer 4

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

Question 5

When is the cranial growth depicted

Answer 5

Dictated in-utero

Question 6

Why is the brain ~25% formed at birth

Answer 6

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

Question 7

What is special about fontanelles

Answer 7

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

Question 8

What does the neonate minimal development have as a positive

Answer 8

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

Question 9

Where are both of the fontanelles and when does one close

Answer 9

Anterior and posterior, posterolateral fontanelle

Anterior closes at ~18 months

Question 10

What is an eminence

Answer 10

Bone that protrudes slightly frontal and parietal

Converted of ossification

Question 11

How can a baby not hold up its head

Answer 11

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

Question 12

What is the difference between the pelvic inlet and outlet

Answer 12

Inlet - transverse diameter > AP diameter

Outlet - transverse diameter

Question 13

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

Answer 13

Neonate - 8:1

Adult - 2.5:1

Question 14

What influences the growth of the jaw

Answer 14

The development and eruption of teeth

Wisdoms don’t

Question 15

How are various processes of the skull formed

Answer 15

As muscles attach to bones pull on them developing processes

Question 16

What kind of hormones influence skull growth

Answer 16

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

Question 17

What does the primary cartilaginous joint allow

Answer 17

Synchondroses

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

Question 18

What are the two synchondroses of the skull

Answer 18

Spheno-ethmoidal synchondrosis close at 6

Spheno-occipital activated at birth and close at 25

Question 19

How is the adult skull light

Answer 19

Lightness optimised by 
Diploe
Orbits 
Cavities 
Paranasal sinuses

Question 20

What are the paranasal sinuses

Answer 20

Air filled spaces 
Maxilla 
Sphenoid 
Frontal 
Ethmoid

Question 21

How is the adult skull strong

Answer 21

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

Question 22

What is diploe

Answer 22

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

Question 23

What are the endentulous changes

Answer 23

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

Question 24

What are the three conformational changes of the skull

Answer 24

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