| Line 9: |
Line 9: |
| | | | |
| | | | |
| − | ===Bone organisation===
| |
| − |
| |
| − | *Normal progression is from woven bone to lamellar bone, even in pathology, except for [[Bones - hyperplastic and neoplastic#Craniomandibular osteopathy|canine craniomandibular osteopathy]] and [[Bones - metabolic#Hypervitaminosis D|hypervitaminosis D]], where lamellar bone is replaced by woven bone
| |
| − | *Patterns of collagen deposition:
| |
| − | **'''Woven bone''':
| |
| − | ***"Random weave" which is only a normal feature in the foetus
| |
| − | ***Coarse collagen fibres
| |
| − | ***Later removed by osteoclasts and replaced by lamellar bone
| |
| − | ***In adults it is a sign of a pathological condition (e.g. fracture, inflammation, neoplasia)
| |
| − | **'''Lamellar bone''':
| |
| − | ***Orderly layers which are much stronger than woven bone
| |
| − | ***Fine collagen fibres in concentric or parallel laminae
| |
| − | ***Two main types:
| |
| − | ****'''Compact bone (cortical)'''
| |
| − | *****Forms 80% of total bone mass
| |
| − | *****Consists of cells and interstitial substance - 30% ossein (type of collagen) and 70% minerals, especially calcium phosphate
| |
| − | *****Forms the shell of long bone shafts - contain [[Haversian systems]]
| |
| − | ****'''Cancellous bone (spongy or trabecular)'''
| |
| − | *****Made up of plates, tubes or bars arranged in lines of stress
| |
| − | *****In vertebrae, flat bones and epiphyses of long bones
| |
| − | *****Contains no Haversian systems
| |
| − | **'''Laminar bone'''
| |
| − | ***Formed on periosteal surface of diaphysis
| |
| − | ***Accomodates rapid growth of large dogs and farm animals
| |
| − | ***Plates of woven bone from within the periosteum
| |
| − | ***Concentric plates
| |
| − | ***As it forms, it fuses with the bone surface
| |
| | | | |
| | | | |