Bone - Transverse Section
• Haversian system is considered as the functional anatomical unit of bone.
• Haversian system or osteon is made up of central Haversian canal.
• Around the canal osteoid matrix is laid in layers called lamellae. Between the lamellae osteocytes are placed within the lacunae, which are interconnected by canaliculi.
Lamellae around the canal are called concentric lamellae.
• At periphery running around the bone are circumferential lamellae which are located beneath the periosteum or endosteum.
• Lamellae between the Haversian system are called interstitial lamellae.
• Periosteum is a two-layered structure-outer fibrous and inner cellular layer.
Fibrous layer containing collagen fibers.
Inner cellular layer with osteoprogenitor cells helps in appositional growth/secondary healing
•Three types of cells are seen in bone:
a Osteoblasts are bone-forming cells.
b. Osteoclasts are seen at the sites of bone resorption
c. Osteocytes are older inactive cells, buried between layers of osteoid.
•Matrix is made of ground substance, fibers and inorganic substance mainly calcium and phosphorus.
Bone - Longitudnal Section
• Haversian system is considered as the functional anatomical unit of bone.
• Haversian system or osteon is made up of central Haversian canal containing blood vessels and nerves.
• Around the canal, osteoid matrix is laid in layers called lamellae. Between the lamellae osteocytes are placed within the lacunae, which are interconnected by canaliculi.
• Haversian canals are interconnected by oblique canals called Volkmann's canals.
• At periphery running around the bone are circumferential lamellae which are located beneath the periosteum or endosteum.
• Periosteum is a two layered structure-outer fibrous and inner cellular layer.
a. Fibrous layer containing collagen fibers
b. Inner cellular layer with osteoprogenitor cells helps in appositional growth/secondary healing