skull growth and development Flashcards
prenatal bone development
Endochondral ossification:
Mesenchyme* first forms cartilage model
• Fibroblasts → chondrocytes → cartilage model → ossified.
- Mesenchyme is loose connective tissue found in the developing embryo
Intramembranous
• Mesenchyme forms bone directly
• Fibroblasts → osteocytes → bone
• eg. vault of skull
neonatal skull
Bones of vault are separated by fibrous tissue along their edges (sutures) and at their corners (fontanelles - anterior and posterior).
The sutures and fontanelles function to allow:
i) movement of the skull bones over one another during birth -molding
ii) continued growth of the bones at the edges to accommodate the growing bone.
post natal growth
Growth of cranium (vault and base) calvaria = domelike part
• post and lat fontanelles are usually obliterated shortly after birth;
• bregmatic (anterior) does not usually close till after mid second year.
• This allows for rapid brain growth
• 0- 2 years brain triples in volume. After that growth slows and is at ~90% by 10y.
GROWTH OF FACIAL BONES
Growth in all 3 dimensions (height, width, depth) due to:
i) development of paranasal sinuses
ii) growth of maxillae, mandible
iii) influence of muscle attachment
Maxillary complex:
growth has the effect of shifting the entire complex downwards and forwards due to growth at the following sutures
Mandibular growth
birth mandible is in 2 separate halves –> fused by the end of the first year
adult skull
The body of the mandible elongates and deepens in to accommodate permanent teeth
• Obliteration of the sutures of the vault of skull takes place as age advances
THE SKULL IN OLD AGE
generally becomes thinner and lighter
- the decrease in size of the mandible and maxillae due to loss of teeth and absorption of alveolar process
what are the paranasal sinuses?
frontal
sphenoidal
ethmoidal
maxillary
