Your Amazing Skeleton: The 206 Bones That Hold You Up

Right now, inside your body, you have 206 bones — all working together to help you sit, stand, run, and dance. Here is a cool surprise: babies are born with about 270 bones! As you grow up, some of those bones slowly fuse together (stick together) until you end up with 206 as a grown-up. Your skeleton is like the frame of a building. Without it, your body would have no shape at all!

In this lesson you will: • Learn the three jobs your bones do for your body • Get to know five important bones by name • Find out what joints are and how they help you move • Discover a surprising fact: bones are ALIVE!

Bones are not just for show — they work hard every second of every day! **Job 1 — Hold You Up**: Your skeleton holds your whole body up, like the frame of a house holds up the walls and roof. Without your skeleton, you would be floppy like a jellyfish! **Job 2 — Protect What's Important**: Some bones act like armor. Your skull protects your brain. Your rib cage protects your heart and lungs. **Job 3 — Help You Move**: Bones work with your muscles like a team. When a muscle pulls on a bone, the bone moves — and so do you!

Here are five bones you can even feel with your fingers: **Skull**: The hard shell around your brain. Press gently on the top of your head — you can feel it! It looks like one piece but is actually made of 22 bones that grew together. **Spine (backbone)**: Run your fingers down the middle of your back. Those bumps are your vertebrae — 33 small bones stacked like building blocks. They let you bend and twist while protecting your spinal cord. **Ribs**: Put your hands on the sides of your chest. Those curved bones you feel are your ribs. You have 12 pairs, and they form a cage that keeps your heart and lungs safe. **Femur**: The bone in your upper leg — the biggest, longest, strongest bone in your whole body. **Humerus**: The bone in your upper arm. (Memory trick: It sounds like 'humorous' — as in funny. People call the tingly spot on your elbow the 'funny bone' because of this bone!)

Bones connect to each other at joints. Different joints move in different ways: **Hinge joints** open and close in one direction, like a door hinge. Your elbow and your knee are hinge joints. Try bending your knee sideways — it does not work! It only goes forward and backward. **Ball-and-socket joints** can move in many directions. Your shoulder is a ball-and-socket joint. Try swinging your arm in a big full circle — it can go all the way around! Your hip is a ball-and-socket joint too. Joints have a slippery liquid inside called cartilage that keeps bones from grinding against each other. When you hear a knee pop, that is a tiny bubble in that joint fluid!