Facial Growth Flashcards
what are the two phases of life in utero
embryonic (1-8 weeks)
foetal (8 weeks to term)
what is a potential consequence if the neural folds dont fuse to form the neural tube
spina bifida
fusion occurs around the end of week 3
what develops from the neural tube
brain and spinal cord
what is a potential consequence if the neural tube doesn’t develop
anencephaly - neural tissues bulge from brain
what are the two main divisions? that the face develops from
pharyngeal arches (comes from sides)
fronto nasal process (comes from front)
what processes does the 1st pharyngeal arch split into
mandibular and maxillary
what cranial nerve is assosciated with the 1st pharyngeal arch
CN V - trigeminal
what cranial nerve is assosciated with the 2nd pharyngeal arch
CN VII - facial
intramembranous ossification
bone deposited directly into primitive mesenchymal tissue
form from various centres of ossification which fuse together
give an example of a bone that is formed via intramembranous ossification
flat bones of the skull (vault of skull) e.g frontal, parietals, maxilla
Endochondral ossification
bones are preceeded by a hyaline cartilage ‘model’
‘islands of cartilage’ often remain so that further growth can occur
give an example of a bone that is formed via endochondral ossification
base of skull bones - ethmoid, sphenoid
what form of ossification is the mandible formed from
intramembranous
fontanelles
fusion of intramembraneously formed vault of skull is incomplete at birth leaving widening known as fontanelles
anterior closes at 2 y/o posterior at 1 y/o
How does growth of the skull occur after the fontanelles have closed
growth occurs at fibrous sutures in response to intracranial pressure
(as brain grows so does skull)
stops around age 7
nasal capsule
primary cartilage skeleton of upper face
how does the mandible develop
develops as several units, formation of these units is dependent on growth of associated structures
give 2 examples of a mandible unit and its associated structure (in regards to growth)
coronoid unit - in response to temporalis muscle development
Body unit - IAN
alveolar - teeth
angular - masseter and medial pterygoid
discuss the growth of the mandible post birth
post birth mandible relies on secondary cartilage of which there are 3: condyle, coronoid and symphyseal
Coronoid and symphyseal have both disappeared not long after birth but condylar remains and can see growth until around 20 years old
