Everyone’s got muscles – at least 600 of them!
Some are easy to find like your arm muscles – but others are hidden away, such as in your heart. Your muscles are all very flexible, which allows them to move about.
That’s because they all do something – some help your heart to work, others allow you to walk or run.
Muscles work by tightening and then relaxing.
For example, when the muscle in your upper arm (called the bicep) tightens, it pulls up your lower arm.
Others work all the time without you having to do any work, like your heart muscle which pumps blood around your body, and the muscles around your lungs that make you breathe.
Did you know?
The most important muscle in your body is your heart, which is in charge of pumping blood around your body.
