How Muscles Work

Your body has over 600 muscles. They allow you to walk, run, jump, and even smile. Muscles work by contracting, which means getting shorter and tighter. When a muscle contracts, it pulls on your bones and makes them move. Muscles can only pull. They cannot push.

Types of Muscles

There are three types of muscles. Skeletal muscles are attached to your bones and help you move. You control them by thinking about it. Smooth muscles are in your organs like your stomach and intestines. They work automatically. Cardiac muscle is found only in your heart and never stops working.

How Muscles Move You

Muscles usually work in pairs. When you bend your arm, the bicep muscle on top contracts and gets shorter. At the same time, the tricep muscle on the bottom relaxes and stretches. When you straighten your arm, the opposite happens. Most movements in your body use pairs of muscles working together.

Fun Facts

• The strongest muscle in your body based on its size is the masseter, or jaw muscle.
• It takes 17 muscles to smile but 43 muscles to frown.
• Your heart muscle beats about 3 billion times in an average lifetime.

Did You Know?

Your tongue is actually made up of eight different muscles working together. It is one of the most flexible parts of your body and is the only muscle group that can work without the support of bones!