Imagine a Halloween skeleton hanging from a string. If you cut the string, the skeleton would fall to the ground in a heap. That’s exactly what would happen to you if you had no muscles.
Muscles make it so you can stand and walk. They also let you run, bend, and reach. You use them to smile, cross your fingers, and roll your eyes. They even help your mouth water when you think of tasty food.
Muscles let you move your body in so many ways. And they do it all so simply—just by contracting and relaxing. When they contract, muscles pull on the bones or tissue where they are attached. The pulling lets you move. When they relax, muscles let you rest.
Your body has more than 600 muscles. Every human does. Some muscles are small, thin, and delicate. Others are tough and sturdy. Together, all the muscles make up from 25 to 45 percent of your weight. Each and every muscle has a job to do in keeping you alive and healthy.
