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activity 5 how do muscles work? - Sarah Outen

There are over 150 / 450 / 650 muscles in the human body. They make up nearly 25% / 40% / 80% of your body weight. In your face there are over 10 / 50 / 90 different muscles to help you smile, frown, show that you are cross, surprised or sad. Eye muscles are the busiest muscles in the body. Scientists estimate they move more