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Muscles make up about 40% of total body weight.
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The smallest muscles, like the smallest bones, are found in the middle ear, some of these are the tensor tympani (connected to the ear drum) and the Stapedius.
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Muscles cannot push, they can only pull. The reason the arm can push is muscles in the back of the arm pulling on the elbow!
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The strongest muscles in the body? Pound for pound, it's the muscles that you chew with - called the masseters!
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Humans are born with all of the muscle fibers they will ever have. They don't grow new fibers, they just grow thicker.
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If all of the muscles in the body could all pull in one direction, it would create a force of 25 tons!
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Smiling takes 17 muscles in the face, while frowning takes 43!
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The heart is made up of muscle, called cardiac muscle. This muscle works all by itself with no thought. The heart beats anywhere from 60 to 100 times a minute, every minute, of every day in a human life!
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The skeletal muscles, which are the ones that can be controlled by conscious thought, work with the skeleton, or the bones, to move the body. They attach to the skeleton with tendons, which are cords of tough tissue.
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Some of the biggest muscles are in the back, near the spine. They are responsible for keeping the body upright and gives the body the power it needs to lift and push things.
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Skeletal muscles are also sometimes called striated muscle - this name comes from the light and dark parts of the muscle fibers making them look striped (striated means striped).
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Smooth muscles, which can't be voluntarily controlled, usually occur in sheets or layers, one layer of muscle behind another. These are at work all over your body.
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In the digestive system, the smooth muscles tighten up and relax, moving food through the body.
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Smooth muscles are also found in the bladder. When they are relaxed, the opening in the bladder is closed, which allows urine to stay in the bladder. When someone goes to the bathroom, they contract, which pushes urine out of the bladder.
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Smooth muscles in a woman's uterus, which is where a baby develops and grows, push the baby out when it's time to be born.
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Smooth muscles are even found in the eyes, where they help keep the eyes focused, and help control the amount of light that enters the eye.
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