Muscles

You have more than 640 muscles in your body! Each muscle is a bunch of strings clumped together, like hairs  stuck to ends of bones in your body. They shrink and pull to move ends of bones. Your brain tells the strings when to pull and shrink. The reason there are lots of strings in each muscle, is because they do hard work. Sometimes a hair needs a rest so another hair in the muscles takes over the hard work. Your biggest muscle is…your butt!