Facial Growth 2 Flashcards
How would you describe the size of the face on a baby compared to the head?
The face is small compared to the overall size of the head in newborns
Describe the differences between and adult and neonatal skull.
- infant face is small compared to the cranium, eyes are large and the ears are low set (face takes up 1/2 of face whereas in adult 3/4)
- forehead is upright and bulbous and the face appears broad
- the nasal region is vertically shallow with the nasal floor close to the inferior orbital rim (height of maxilla less)
- in the adult, the midface expands and nasal floor desends
What are the 3 different types of sites of growth/types of growth in the face?
- sutures
- synchondroses
- surface deposion
What is a suture?
It is a specialised fibrous joint situated between intramembranous bone.
Describe the structure of a suture.
A band of connective tissue which has osteogenic cells in the centre and the most peripheral of these cells provide new bone growth
Growth at sutures occurs due to what? Describe how it works.
Growth occurs in response to growing structures separating the bone (e.g. calvarium in response to development of brain)
Where the bones are pushed apar, new bone forms in the suture
Suture growth happens in areas of TENSION
Where are synchondroses found?
In the midline
They exist between the ethmoid, sphenoid and occipital bones
Describe how growth happens at synchondroses.
Has a cartilage based growth centre with growth occuring in both directions
The bones on either side of the sychondrosis are moved apart as growth takes place
New cartilage is formed in the centre of a synchondrosis as cartilage at the periphery is transformed into bone
Describe the bone growth in the face via surface deposition.
New bone is deposited beneath the periosteum over the surfaces of both the cranial and facial bones
How is the shape of bones maintained during growth?
Resorption also takes place
(the process of growth and deposition is also known as remodelling)
What is the change in positio of a bone due to remodelling known as?
Drift
e.g. cortical drift
What bones is the cranial vault composed of?
Frontal bone
Temporal
Occipital
Parietal bones
What does the cranial vault grow in response to and till what age?
Expands in response to the growing brain until age 7
When is the rate of growth of the cranial vault the greatest?
In the first 3 years of life
What are the 2 ways that the bone grows in the cranial vault?
- bone growth at sutures
- external and internal surfaces are remodelled through surface deposition and resorption to displace the bones radially (resorption on internal surface of calvarian
After neural (brain) growth ceases the forehead continues to enlarge in response to what?
In response to the expanding air sinuses (pneumatisation)
Note: generally more pronounced in males
Where do fontanelles exist? How many are present at birth and when do they close by?
Where more than 2 bones meet together.
6 present at birth and close by 18months