Face and jaw

Question 1

how are traumatic forces to the maxilla dissipated?

Answer 1

• the maxilla is a thin and hollow bone, which means that upon a traumatic force, its able to crumple on it self (act as a crumple zone) rather than being driven into the base of the skull and damaging the brain
• also Le Fort fracture patterns help to separate the face from the base of the skull

Question 2

what are the Le Fort fracture patterns?

Answer 2

there are three different patterns:
Le Fort I, II and III

Le fort III being the worst severe of the fracture patterns as it separates bones of the face from bones of the cranial vault

Question 3

how are traumatic forces to the mandible dissipated?

Answer 3

mandible a thick n dense bone, so it can absorb forces to a certain extent. otherwise, it will fracture, avoiding being driving into the base of the skull via the TMJ condyle.

Question 4

how are masticatory forces to the mandible dissipated?

Answer 4

the mandible is a thick and dense bone, therefore, its ability to dissipate the occlusal forces across itself with no problem.

Question 5

how are masticatory forces to the maxilla dissipated?

Answer 5

the maxilla is thin and hollow therefore to avoid fracturing, the occlusal forces need to be transferred towards the neurocranium by a system called ‘ Buttress System ‘

Question 6

Describe the Buttress system

Answer 6

it enables the occlusal forces from the maxilla to be dissipated towards the neurocranium (keeping away from delicate orbits and nasal areas).

therefore maxilla has 3 strengthened areas which these forces channel through towards the vault of the skull: (called craniofacial buttress)

• Pterygoid
• Zygomatic
• Frontonasal

Question 7

name the 5 design features of an adult skull which maximise the chance of survival

Answer 7

1 - strength
2 - lightness (by dipoles, hollow bones, orbits)
3 - keeping airways open
4 - warming and humidifying the air breathed in
5 - supporting muscles involved in mastication and swallowing

Question 8

describe the ‘strength’ design feature of the brain

Answer 8

• spherical shape: max volume and strength, min weight and SA
• suture joints
• buttress system
• crumple zones
• orbital rim around the eyeballs

Question 9

What’s the conflict in the neonatal skull?

Answer 9

size of the head is a problem for the mother, but the bigger the head, the bigger the brain so higher the chance of survival

Question 10

what are the design features of the neonatal skull to facilitate birth?

Answer 10

Deformable skull: (needs to mould within the birth canal)

• wide sutures
• thin and deformable bones

Minimal development of inessential parts:

• small jaw (liquid diet)
• small nose (no sense of smell)

Question 11

whats dermatocranium?

Answer 11

flat bones of the neurocranium

Question 12

describe the structure of dermatocranium dipoles

Answer 12

the dematocranium contains 3 layers:

An outer plate of compact bone (scalp side)
Dipoles
The inner plate of compact bone (brain side)

the dipole sits in between the two layers of compact bone

Question 13

describe the function of dermatocranium dipoles

Answer 13

• dipoles confer lightness, strength and flexibility
• if the outer layer of the contacting bone is fractured, dipoles stop forces from transferring to the inner plate of compact bone, avoiding injuries to the brain