Facial Growth Flashcards
What are the 2 stages of in utero development?
Embryonic - 1-8 weeks
Foetal - 8 weeks to full term
Why do we treat GROWING children?
We can predict changes
We can utilise growth to correct malocclusion
We can time orthodontics and surgery
What condition occurs if the neural tube does not fuse?
Spina bifida
What nerve and muscles are derived from the 2nd pharyngeal arch?
The facial nerve and the muscles of facial expression
Associated with Reichert’s cartilage
What nerve and muscles are derived from the 1st pharyngeal arch?
The trigeminal nerve and the muscles of mastication
Associated with Meckel’s cartilage - which goes on to form the lower jaw
How is it that cleft lip and palate can happen independently of one another?
They upper lip and anterior part of the palate have different embryological origins from the posterior palate and they fuse at different times.
Why is facial growth important?
The size, shape and position of the underlying jaws determines the position of the teeth and therefore malocclusion.
What weeks in utero is most of face development done?
Mainly in the first 8 weeks
What are the 2 parts of the skull?
Neurocranium - brain
Viscerocranium - skeleton of the facew
What type of bone formation forms the neurocranium and viscerocranium?
Neurocranium - intramembranous ossification
Viscerocranium - endochondral ossification
Briefly describe intramembranous bone formation
Bone is deposited as a direct conversion of mesenchyme into bone.
Osteoblasts group into clusters and form an ossification centre.
Typically for flat bones.
Briefly describe endochondral bone formation.
Where hyaline cartilage model is then replaced by bone.
Occurs at epiphyseal plates in long bones - bones that need to grow - limbs, spine, ribs and VISCEROCRANIUM.
What bone is not ossified at birth?
The nasal septum - not ossified as this is important for forwards and downward growth of the maxilla
What type of bone formation are the maxilla and mandible formed by?
Intramembranous bone formation but are preceded by a CARTILAGENOUS facial skeleton
What is hemifacial microsomia and how does it occur?
It is a 3D progressive facial asymmetry
Occurs due to lack of neural crest cells migrating to the front on one side during fusion of the 2 neural folds.
How does Treacher Collin’s syndrome occur?
The neural crest cells do not migrate at all on either side of the neural tube.
Deficiency of 1st and 2nd branchial arches
Roughly what days in utero do the lips fuse?
28-38 days