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46 bytes removed ,  13:59, 28 September 2007
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***"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:
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**'''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===
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===Periosteum and blood supply===  
   −
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.
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*Specialised sheath of connective tissue covering bone except at the articular surfaces
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*Inner layer  
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**Merges with the outer layer of bone
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**Contains osteoblasts and osteoprogenitor stem cells
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*Damage to the periosteum invokes a hyperplastic reaction of the inner layer
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*The blood supply to the mature bone enters via the periosteum
   −
The blood supply to the mature bone enters via the periosteum.  Damage to the periosteum invokes a hyperplastic reaction of the inner layer.
     −
Bone development
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===Bone development===
There are two main types of bone development:
  −
• Endochondral ossification (cartilage model)
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o Long bones mainly
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o Cartilage model is vascularised and centres of ossification develop.  The latter are primary (diaphyseal) and secondary (epiphyseal)
     −
Intramembranous ossification  
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*Two main types of bone development:
o Flat bones mainly (e.g. skull)
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**'''Endochondral ossification''' (cartilage model)
o Mesenchymal cells differentiate into osteoblasts.  There is no cartilage precursor template
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***Long bones mainly
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***Vascularised
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***Developed centres of ossification
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****Primary (diaphyseal)
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****Secondary (epiphyseal)
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**'''Intramembranous ossification'''
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***Flat bones mainly (e.g. skull)
 +
***Mesenchymal cells differentiate into osteoblasts
 +
***No cartilage precursor template
    
Physis
 
Physis
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