Ossification
Fibrous / Cartilage cells being replaced by bone cells
Intramembranous Ossification (Which Bones?)
Face and Skull
Endochondral Ossification (Which Bones?)
Limbs, Vertebrae, Thoracic, Pelvic
Intramembranous Ossification (What is it?)
Bone formation from fibrous tissue
Endochondral Ossification
Bone formation from cartilage
Intramembranous Ossification (Process?)
- Mesenchyme differentiate into osteoblasts which produce osteoid
- Osteoid are buried and become osteocytes
- Bone grows to form spicules
- Blood vessels are entrapped
- Osteoblasts continue to deposit and then form spongy bone
Endochondral Ossification (Process?)
- Chondrocytes at the diaphysis grow
- Blood vessels grow around cartilage
- Perichondral form Periosteum (Inner layer forms thin bone layer)
- Cartilage Cells die and are replaced by osteoblasts
Forms spongy bones
Primary Ossification Center - Cartilage at metaphysis is invaded by osteoblasts
- Bone increases in diameter
- Osteoblasts migrate into epiphysis
Secondary Ossification Center - Osteoblasts replace cartilage with bone
- Epiphysis is pushed away from diaphysis –> Longer Bone
Interstitial Growth
Chondrocytes in matrix divide
Daughter Cells secrete matrix
Cartilage Expand
Appositional Growth
- Inner layer of periosteum differentiates to form osteoblasts
- Bone matrix added to surface
- Forms more layers on the bone surface and increases its diameter
How do bones grow in width and diameter
Central Endosteal Resorption
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Periosteal Deposition
How do bones grow in length?
Apposition at Epiphyseal Growth Plates
Epiphyseal Growth Plate
Cartilage that is only present in the growth phase.
Starts at diaphysis (Primary Ossification Centre)
Ends at epiphysis (Secondary Ossification Centre)
Articular Cartilage
Cartilage at the Ends of Bones
Prevents damage from bone-bone contact
Epiphyseal Closure
Cartilage near the diaphysis is converted into bone
Width gets more narrow as we age until it finally disappears, marks the former location of the epiphyseal cartilage
Epiphyseal Line
Cartilage at the metaphysis, formerly the epiphyseal cartilage.
Nutrient Foramen
Where artery, vein, nerves enter through bone
Nutrient Vessels
Enters the nutrient foramen of bone
- Penetrates the shaft of diaphysis and enters the medullary cavity
- Divides into ascending and descending branches towards epiphysis
Sensory Nerves
Enter the bone through the nutrient foramen with the nutrient artery
Metaphysis Vessels
Supply nutrient to the diaphyseal edge of the epiphysis
Epiphyseal Vessels
Supply nutrients to the cavities of the epiphysis
Periosteal Vessels
Supply nutrients to the superficial osteons
Regulating Bone Growth (Minerals)
Needed for proper bone formation
Regulating Bone Growth (Vitamin A)
Stimulates Osteoblasts
Regulating Bone Growth (Vitamin C)
Needed for Collagen Formation and Osteoblast Differentiation
