Microscopic Structure of Bone: Haversian System

Bone Structure Overview

Bone Cross-Section: Reveals two main types of bone tissues:
- Spongy Bone: Also known as cancellous or trabecular bone
  - Looks like sponge due to trabeculae
  - Surface area is 10x that of compact bone
  - Porous network around bone marrow
  - Makes the bone lighter
- Compact Bone: Denser, harder outer layer
  - Has fewer gaps/spaces
  - Organized into osteons (Haversian system)

Each osteon is cylindrical and consists of multiple concentric layers (lamellae)
Haversian Canal (central canal): Center of osteon
- Contains blood vessels, lymph vessels, and nerves
Canaliculi: Tiny channels between lamellae
- Connect central canal to lacunae (empty spaces)
- Lacunae contain osteocytes (bone cells)
- Osteocytes have long processes that reach through canaliculi
- Allow for cell communication and nutrient exchange via gap junctions
Volkmann's Canals: Run perpendicular to Haversian canals
- Connect osteons
- Also contain small blood vessels