4 Your Body

Your body

Your amazing body. Your body is like a complicated machine, always working to keep you alive. Computer scans can show the different parts that make up a person's body.

Bony frame. Your skeleton is a frame of bones that gives your body shape and covers its soft parts. You were born with about 300 bones. Many of them join together as you grow. Adults have 206 bones. Femurs are the biggest bones.

Places where bones meet are called joints. Joints let you bend and twist. Straps called ligaments hold bones together. A slippery liquid helps bones move smoothly.

Mighty muscles. Muscles are rubbery and stretchy. They are often attached across two bones and help the bones move. When one muscle tightens, it makes a bone move. Then another muscle tightens to move the bone back.

This picture shows the muscles in your arm and hand. They pull on bones so that you can move your elbow, wrist and fingers. You have about 60 face muscles. They let you make lots of expressions.