Muscles that move the body are called skeletal muscles. There are about 640 of them and they give the body its shape. Skeletal muscles are attached to bones. They work by contracting, or getting shorter. When a muscle contracts, it pulls the bone it is attached to. Skeletal muscles produce all movements, including running and chewing.
Different Shapes and sizes
Muscles vary in size and shape and are found all over the body. The longest are in the thigh. The biggest are the buttock muscles used in climbing and running. The tiniest muscles are inside the ear.
Tendons
Muscles are joined to bones by tough cords called tendons. When a muscle contracts, it pulls the tendon, which then pulls the bone. The Achilles tendon is a large tendon that joins the calf muscle to the heel bone.
Making a Face
There are more than 40 small muscles in the face and neck. When they contract, they pull on the skin of the face to produce a wide range of facial expressions. These expressions, which include frowning and smiling, show whether a person is feeling sad, happy, angry, or frightened.
Muscle Pairs
Muscles usually work in pairs, with each muscle causing opposite movements. These are called antagonistic muscles. In the arm, the biceps muscle contracts and shortens to bend
The arm at the elbow. The triceps contracts to straighten the arm.
AMAZING FACTS
Muscles make up nearly half the body’s total weight.
Whether a person is asleep or awake, muscles move the eyes 100,000 times every day.
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