Compact bone, also known as cortical bone, is the denser and stronger of the two main types of bone tissue. It forms the hard outer layer of all bones and surrounds the bone marrow. This dense structure provides significant support and protection to the body.
Structure and Composition
The microscopic structural unit of compact bone is the osteon, also called a Haversian system. Each osteon consists of concentric rings of bone tissue surrounding a central canal (the osteonic or Haversian canal), which contains blood vessels and nerves. These canals provide nutrients and remove waste products from the bone cells (osteocytes). The tightly packed osteons contribute significantly to the strength and density of compact bone. The bone matrix itself is composed of organic ground substance and inorganic salts, leaving only tiny spaces between the structural units.
Function and Location
Compact bone's primary functions are support and protection. It's found:
- Under the periosteum (the outer membrane covering bone).
- In the diaphyses (shafts) of long bones.
These locations highlight its crucial role in providing structural integrity and shielding vital organs.
Properties and Applications
Research on compact bone includes studying its:
- Ultimate properties: Scientists investigate its strength under tension, compression, and torsion. This informs understanding of bone fracture mechanics.
- Fatigue behavior: Studies examine how repeated stress affects compact bone's strength, revealing factors influencing bone fracture risk.
- Microstructural aging: Researchers investigate changes in compact bone composition with age.
- Mechanical properties: Analysis focuses on defining and analyzing the various mechanical properties of compact bone to better understand bone strength and function.
The study of compact bone is critical for orthopedic research, trauma care, and understanding age-related bone diseases. Its unique structure and mechanical properties make it a fascinating and important area of ongoing research.
