Craniofacial developmental disorders Flashcards
what gradient describes growth?
cephalocaudal gradient
what are the 3 characteristics of growth?
indivudal variability
normal variation
pattern v timing
what is the main trend seen in scammon’s curves (tissue systems)?
neural growth occurs very rapidly in early stages of first year of life and then tails off
when is the pubertal growth spurt?
8-12 year
what are the 4 types of growth in the craniofacial complex?
cranial vault
cranial base
nasomaxillary complex
mandible
what are the 3 distinct regions (embryonic origins) of the skull?
desmocranium
chondrocranium
viscerocranium
what is the chondrocranium?
cartilage based
what is the viscerocranium?
facial tissues
what is the desmocranium?
vault housing the brain
what is the process of bone development from fibrous membrane?
intra-membranous ossification
what happens prior to sutural growth?
fontanelle fusion
what are the main skull sutures?
coronal
lambdoid
formator
posterior
parietal
what happens to the sutures as the brain grows and bone moves apart ?
sutural infill
how does the skull remodel to accommodate neural growth?
resorption on inside
deposition on outside
what is hydrocephaly?
brain grows to an abnormally large size
what is microcephaly?
problem in neural development
what virus is associated with micrcephaly?
zeco virus
what is craniosynostosis?
premature fusion of cranial sutures which prevent brain expanding skull normally
results in protrusion of eyeballs
what is proptosis?
protrusion of eyes
what is crouzon syndrome?
craniosynostosis
what is apert syndrome?
coronal and lambdoid fusion - brain expands front and back instead of transversely
what is turricephaly?
tall head with small length and width
what is plagiocephaly?
saggital and coronal fusion
what is trigonocephaly?
triangular forehead
what type of ossification occurs in the cranial base?
endochondral
what is synchondrosis?
a type of cartilaginous joint where hyaline cartilage completely joins together two bones
where are centres of ossification in the chondrocranium?
either side of synchondrosis
what is endochondral mechanism in the chondrocranium?
cartilage grows rapidly and replaced by bone
how are ethmoid, sphenoid and basioccipital bones formed in the chondrocranium?
cartilage interposed between large sections of bone
how is nasomaxillary complex formes?
begins at nasal cartilage
in adult, becomes intramembranous ossification of maxilla, nasal and zygomatic
apposition of bone at sutures
bone remodelling
when does bone remodelling occur?
after bones are formed
what process allows face to grow downwards?
sutural growth of the circum-maxillary sutures
how is mandible formed?
condyle endochondral activity
periosteal activity
what is a precursor of the mandible?
meckels cartilage
when do condylar cartilage seperate?
early stages of foetal development before birth
where do teeth develop?
alveolar process
what are the components of the developing mandible?
condylar process
coronoid process
angular process
alveolar process
body
chin unit
what is the role of the condylar cartilage?
downward and forward transposition of mandible via cranial base
bone deposition and resorption
what is the complex growth rotation called?
Bjrok
what is an environmental influence on growth?
orthodontic appliance
what is a homebox gene?
master developmental control genes
what is the role of homebox genes?
craniofacial shape and patterning
patterning of the dentition
what do homebox genes encode?
transcription factors
what do homebox genes control?
epithelial/ mesenchymal interaction
how do homebox genes work?
through neural crest cells
where is the origin of facial mesenchyme?
neural crest
what homebox genes are involved in tooth development?
MSX1
MSX2
what is tooth development information expressed through?
mesenchymal growth factors - FGF, EGF, TGF, BPM
what happens during week 4 NCC migration?
NCC migration populates branchial arches
what are features of treacher collins syndrome?
down slanting fissures
low set ears
maxillary hypoplasia
cleft
what is missing in treacher collins syndrome?
condylar process
zygomatic arches
what is absent in hemifacial microsomia?
ramus
why is the ramus absent in hemifacial microsomia?
haemorrhage of stapedial artery
what are the types of cleft lip?
unilateral
bilateral
when does the primary palate fuse?
week 6 day 44
when do the palatal shelves elevate?
week 7 day 54
when does the secondary palate fuse?
week 8 day 58
