Bone structures change based on four main types: long bones, short bones, flat bones, and irregular bones. Each type has its own special features and ways of adapting.

1. Long Bones (like the femur)

   • They have a long shaft with two ends and are important for supporting weight and helping us move.
   • About 80% of our bones are long bones.
   • They can grow longer and denser when we put them under stress, like when we exercise. This is known as Wolff's Law, which means bones get stronger with added weight.

2. Short Bones (like the carpals in your wrist)

   • These bones are shaped like cubes and help provide stability without much movement.
   • They adapt to different pressures by spreading the stress over their surface area.
   • Most of these bones are made up of spongy bone, usually about 90%.

3. Flat Bones (like the sternum or breastbone)

   • They protect our internal organs and are spots for muscles to attach.
   • Flat bones get thicker through a process called appositional growth. They can grow thicker by up to 10% depending on how much our muscles are used.

4. Irregular Bones (like the vertebrae in your spine)

   • These bones have complicated shapes and serve many purposes.
   • They can change shape in certain areas in response to the stresses around them, giving support and flexibility where needed.

Overall, bones are always changing and adapting based on the forces they experience. Under consistent stress, they can even increase their mineral content by up to 30%.