Facial Growth 2 Flashcards
What cells make the majority of the face?
Neural crest cells (ectomesenchyme)
What processes develop the facial skeleton?
- Frontonasal processes
- Maxillary + mandbular process
- From the 1st brachial arch
What is formed by intramembranous ossification? (2)
- Vault of skull
2. Mandible + maxilla
What is formed by endochondral ossification?
Base of skull
Define a suture
Specialised fibrous joints between intramembranous bone
What does each suture contain?
Each suture is a band of connective tissue
- With osteogenic cells in the centre
List sites of facial growth (3)
- Sutures
- Synchondroses
- Surface deposition
Where are synchondroses found?
Found in the midline
Between the ethmoid, sphenoid + occipital bones
What makes up the cranial vault? (4)
Frontal
Occipital
Temporal
Parietal bones
What 2 ways does growth at the cranial vault occur?
- Bone growth at sutures
2. External + internal surfaces remodelled through surface deposition + resorption
How many fontanelles are present at birth?
6
When do fontanelles close?
By 18 months
What makes up the cranial base? (4)
Frontal
Occipital
Ethmoid
Sphenoid
How does growth occur in the cranial base?
- Endochondral ossification at synchondroses
2. Surface remodelling at synchondroses
When does half of the cranial base growth occur by?
Age 3
When does the spheno-ethmoidal synchondrosis fuse at?
7yrs
When does the spheno-occipital synchondrosis close at?
13-15yrs in females
15-17yrs in males
Fuses by age 20
How is the maxilla displaced?
Maxilla is displaced downwards + forwards relative to the anterior cranial base
Where does surface deposition and resorption occur in the maxilla/nasomaxillary complex? (2)
DEPOSITION
- Lower border of hard palate + alveolar process
RESORPTION
- On the floor of the nasal cavity + floor of orbits
How is the mandible displaced?
Grows downwards and forwards
How does growth occur by surface remodelling in the mandible?
RESORPTION
- Anteriorly + lingually
DEPOSITION
- Posteriorly + laterally
Results in an increase in height of the ramus + increase in length of the dental arch
Compare lengths of mandible and maxilla
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
At what age does the growth of the maxilla begin to proceed very slowly?
After 7 years
When does growth of the mandible slow down?
17 in females
19 in males
