Changes

===Periosteum and blood supply===  

===Periosteum and blood supply===  

*Specialised sheath of connective tissue covering bone except at the articular surfaces

*Inner layer  

**Specialised sheath of connective tissue covering bone except at the articular surfaces

**Merges with the outer layer of bone

**Loosely attached except at tendon insertions and boney prominences (associated with major blood vessels penetrating bone)

**Contains osteoblasts and osteoprogenitor stem cells in young animals and in adults with fractures or disease

*Damage to the periosteum invokes a hyperplastic reaction of the inner layer

***Outer layer - fibrous for support

*The blood supply to the mature bone enters via the periosteum

***Inner layer - osteogenic

****Contains osteoblasts and osteoprogenitor stem cells in young animals and in adults with fractures or disease

**Damage to the periosteum invokes a hyperplastic reaction of the inner layer

 

**Normal flow of blood from medulla to periosteum due to higher pressures in medulla

*'''Endosteum''' lines the marrow cavity

*'''Endosteum''' lines the marrow cavity