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Bone Response to Damage (view source)
Revision as of 13:59, 28 September 2007
, 13:59, 28 September 2007no edit summary
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−The periosteum is a specialised sheath of connective tissue covering bone except at the articular surfaces. The inner layer merges with the outer layer of bone and contains osteoblasts and osteoprogenitor stem cells.+The blood supply to the mature bone enters via the periosteum. Damage to the periosteum invokes a hyperplastic reaction of the inner layer.
−There are two main types of bone development:
−• Endochondral ossification (cartilage model)
−o Long bones mainly
−o Cartilage model is vascularised and centres of ossification develop. The latter are primary (diaphyseal) and secondary (epiphyseal)
−• Intramembranous ossification +o Flat bones mainly (e.g. skull)+o Mesenchymal cells differentiate into osteoblasts. There is no cartilage precursor template+
***"Random weave" which is only a normal feature in the foetus
***"Random weave" which is only a normal feature in the foetus
***In adults it is a sign of a pathological condition (e.g. fracture, inflammation, neoplasia)
***In adults it is a sign of a pathological condition (e.g. fracture, inflammation, neoplasia)
−**Lamellar bone:
+**'''Lamellar bone''':
***Orderly layers which are much stronger than woven bone
***Orderly layers which are much stronger than woven bone
***Two main types:
***Two main types:
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===Periosteum and blood supply===
+===Periosteum and blood supply===
−*Specialised sheath of connective tissue covering bone except at the articular surfaces
+*Inner layer
+**Merges with the outer layer of bone
+**Contains osteoblasts and osteoprogenitor stem cells
+*Damage to the periosteum invokes a hyperplastic reaction of the inner layer
+*The blood supply to the mature bone enters via the periosteum
−Bone development
+===Bone development===
−*Two main types of bone development:
−**'''Endochondral ossification''' (cartilage model)
−***Long bones mainly
+***Vascularised
+***Developed centres of ossification
+****Primary (diaphyseal)
+****Secondary (epiphyseal)
+**'''Intramembranous ossification'''
+***Flat bones mainly (e.g. skull)
+***Mesenchymal cells differentiate into osteoblasts
+***No cartilage precursor template
Physis
Physis