How Bones Grow

Your bones are not just hard, lifeless sticks. They are living tissue that grows, heals, and changes. Babies are born with about 270 bones. As you grow, some bones fuse together. Adults end up with 206 bones. Your bones keep growing until you are about 25 years old.

How Bones Get Longer

Bones grow at special areas near their ends called growth plates. These plates are made of softer cartilage. New cartilage cells form and push older ones toward the middle of the bone. The older cells harden into bone. This is how your bones get longer. When you finish growing, the growth plates harden completely.

Keeping Bones Strong

Bones are always rebuilding themselves. Old bone cells are removed and new ones take their place. Eating foods with calcium and vitamin D helps keep bones strong. Exercise also strengthens bones because the stress of activity tells your body to build more bone. Drinking milk and being active are great for your bones.

Fun Facts

• A baby's skeleton is mostly made of soft, flexible cartilage that slowly turns into hard bone.
• The smallest bone in your body is the stapes in your ear. It is about the size of a grain of rice.
• Bones are about five times stronger than a steel bar of the same weight.

Did You Know?

If you break a bone, it can heal itself. Your body sends special cells to the break that form new bone. A healed bone is often even stronger at the break point than it was before!