Facial Growth 2

Question 1

What cells make the majority of the face?

Answer 1

Neural crest cells (ectomesenchyme)

Question 2

What processes develop the facial skeleton?

Answer 2

1. Frontonasal processes
2. Maxillary + mandbular process
   - From the 1st brachial arch

Question 3

What is formed by intramembranous ossification? (2)

Answer 3

1. Vault of skull

2. Mandible + maxilla

Question 4

What is formed by endochondral ossification?

Answer 4

Base of skull

Question 5

Define a suture

Answer 5

Specialised fibrous joints between intramembranous bone

Question 6

What does each suture contain?

Answer 6

Each suture is a band of connective tissue

- With osteogenic cells in the centre

Question 7

List sites of facial growth (3)

Answer 7

1. Sutures
2. Synchondroses
3. Surface deposition

Question 8

Where are synchondroses found?

Answer 8

Found in the midline

Between the ethmoid, sphenoid + occipital bones

Question 9

What makes up the cranial vault? (4)

Answer 9

Frontal
Occipital
Temporal
Parietal bones

Question 10

What 2 ways does growth at the cranial vault occur?

Answer 10

1. Bone growth at sutures

2. External + internal surfaces remodelled through surface deposition + resorption

Question 11

How many fontanelles are present at birth?

Answer 11

6

Question 12

When do fontanelles close?

Answer 12

By 18 months

Question 13

What makes up the cranial base? (4)

Answer 13

Frontal
Occipital
Ethmoid
Sphenoid

Question 14

How does growth occur in the cranial base?

Answer 14

1. Endochondral ossification at synchondroses

2. Surface remodelling at synchondroses

Question 15

When does half of the cranial base growth occur by?

Answer 15

Age 3

Question 16

When does the spheno-ethmoidal synchondrosis fuse at?

Answer 16

7yrs

Question 17

When does the spheno-occipital synchondrosis close at?

Answer 17

13-15yrs in females

15-17yrs in males

Fuses by age 20

Question 18

How is the maxilla displaced?

Answer 18

Maxilla is displaced downwards + forwards relative to the anterior cranial base

Question 19

Where does surface deposition and resorption occur in the maxilla/nasomaxillary complex? (2)

Answer 19

DEPOSITION
- Lower border of hard palate + alveolar process

RESORPTION
- On the floor of the nasal cavity + floor of orbits

Question 20

How is the mandible displaced?

Answer 20

Grows downwards and forwards

Question 21

How does growth occur by surface remodelling in the mandible?

Answer 21

RESORPTION
- Anteriorly + lingually

DEPOSITION
- Posteriorly + laterally

Results in an increase in height of the ramus + increase in length of the dental arch

Question 22

Compare lengths of mandible and maxilla

Answer 22

MANDIBLE
Increases in length by 26mm in males
Increases in length by 20mm in females between ages 4-20

MAXILLA
Increases in length by 8mm in males
Increases in length by 5.5mm in females between ages 4-20

Question 23

At what age does the growth of the maxilla begin to proceed very slowly?

Answer 23

After 7 years

Question 24

When does growth of the mandible slow down?

Answer 24

17 in females

19 in males

Question 25

When does growth of maxilla slow down?

Answer 25

12

Question 26

When is tx that utilises the growth of the mandible most effective?

Answer 26

During pubertal growth spurt

Question 27

When is tx that utilises the growth of the maxilla most effective?

Answer 27

Before the circumaxillary sutures + palate have fused - early teens

Question 28

How can growth be utilised to help ortho tx?

Answer 28

1. Functional appliances
2. Rapid maxillary expansion
3. Protraction headgear

Question 29

What is a growth rotation due to?

Answer 29

Imbalance in the growth of the anterior + posterior face heights

Question 30

What does a forward growth rotation lead to?

Answer 30

Short face

Deep bite

Question 31

What does a backward growth rotation lead to?

Answer 31

Long face

AOB