Flashcards in CFD9- Skull growth Deck (50)
what is the need to understanding facial growth?
-aetiology of malocclusion
-recognise abnormal growth patterns
-Best plan of treatment: functional appliances vs orthognathic surgery
-Understand factors that influence treatment stability
Name the primary cartilages.
-meckel's cartilage : contribute to mandible development
-Reichert's cartilage the 2nd arches cartilage
what is the role of primary cartilages?
Primary skeletal support of developing structures
what is the structure of primary cartilage?
what is the fate of primary cartilages
- ossify e.g. part of nasal capsule (some remain)
- disappear e.g most of meckel's cartilage
what are the 2 craniums of the skull?
what is the bones that hold the brain (brain case)?
what is the bones that form the facial skeleton?
what are the 2 divisions of the neurocranium?
-Dermatocranium : cranial vault (intramembranous formed bones)
-Chondrocranium : cranial base (cartilage forms bone)
when do the primary cartilages appear?
7 weeks IU
name some primary cartilages.
what happens to the primary cartilages?
cartilages fuse together and from a network of primary cartilages
what are the bones of the cranial base?
-Temporal bone-petrous part
what type of ossification forms the cranial base?
-endochondral ossification (cartilage converts to bone)
what are the dermal/membranous bones of the cranial vault?
-squamous part of temporal and occipital bones
what ossification forms the cranial vault?
what are the bones from anterior to the coronal suture derived from?
ectomesenchyme (neural crest)
what are the bones posterior to the coronal suture derived from?
mesenchyme (mesoderm) derived
what does ectomesenchyme/ mesenchyme differentiate into?
when does bone formation of cranial vault start?
8 weeks in utero
where do bones meet?
what occurs at sutures?
what are synchondroses?
cartilage joints at the base of the skull
what is the difference in neural and somatic growth?
-Neural growth happens quickly so dermatocranium almost fully formed by the age of 12
-Somatic growth is slower- reaches full size at around age 20
what is sutural growth due to?
expansion of underlying structures (i.e brain)
-osteoblasts on surface lay down bone
-brain expands and the suture is stretched and causes tension between the 2 areas
-osteoblasts need to work harder to lay down more bone
what are fontanelles?
- Soft spots- in a new born skull the sutures are wide open - fibrous tissue over the brain
- gradually close up
what are fontanelles for?
skull is flexible so when the baby is born , the head is squished and bones are compressed and overlap
How long do the fontanelles take to close?
-anterior (closes 6-18 months)
-posterior (closes 1-3 months)
-anterolateral (closes 6 months)
-posterolateral (closes 6-18 months)
what is a sychondrosis?
-Immovable cartilage joint
-active growth sites
-pushes bones apart