Surface of bone is covered by periosteum.- Outer fibrous layer: Protects bones, provides attachment for tendons and ligaments.- Inner cellular layer: Progenitor stem cells that develop into osteoblasts and chondroblasts.

Diaphysis:- Cortical bone contains osteons. → Each osteon is made of many lamellae (concentric layers made of collagen and hydroxyapatite)→ In the center of each Osteon is a Haversian canal (blood supply & innervation).- Medullary canal (inner bone)→ Hollow space lined by spongy/cancellous bone. → Contains bone marrow.

Epiphysis:- Made of spongy bone out of crosslinking roads called trabeculae (resistant to mechanical stress).- Spaces in the spongy bone occupied by bone marrow.