Cortical Bone
The hard, dense outer layer of bone that forms the shaft and outer surface, capable of preserving DNA for decades under proper burial conditions.
The dense, compact outer layer of bone that comprises roughly 80% of skeletal mass. It surrounds the inner spongy bone and provides structural strength and rigidity. Cortical bone is highly mineralized and can preserve biological material like DNA for extended periods when buried under stable conditions.
What this means in real life
When you break your arm, the fracture typically occurs in cortical bone—the hard outer shell you can feel under your skin. This is why cortical breaks are often cleaner and more stable than breaks in the spongy interior.
What it isn’t
Cortical bone is not the same as cartilage, which is softer and more flexible. Many people confuse bone types, but cortical bone is the rigid, mineralized tissue that gives skeleton its strength, not the smooth cushioning material at joint ends.
Commonly misused online
Social media often uses 'cortical bone' interchangeably with 'bone density' in fitness posts, but cortical bone is a specific tissue type, not a measure of overall bone strength or mineral content.