What’s inside our bones?Bone accounts for one sixth of your body's weight. Its clever structure means it's often lighter than it looks.
Marrow can be found in the spine, skull, and the main leg and arm bones
Spongy boneParts of some bones have a honeycomb structure with lots of spaces. This makes them weigh less than if they were solid right through.
Bone marrowA jellyfish substance called marrow fills the center of many of your larger bones. It supplies your body with red blood cells at a rate of 3 million cells per second.
Compact boneThe hardest and most dense part of the bones is the outer layer. It is made of calcium, a substance we get from our food. Teeth are made of calcium too.
What are the most commonly broken bones?