Muscle Muscle is the tough, elastic tissue that makes body parts move. All animals except the simplest kinds have some type of muscle.
People use muscles to make various movements, such as walking, jumping, or throwing.
Muscles also help in performing activities necessary for growth and for maintaining a strong, healthy body. For example, people use muscles in the jaw to chew food. Other muscles help move food through the stomach and intestines, and aid in digestion. Muscles in the heart and blood vessels force the blood to circulate. Muscles in the chest make breathing possible.