According to HowStuffWorks, the famous myth that the tongue is the strongest muscle in the body is not true. The tongue is made up of skeletal muscle fibers, allowing its owner to control it voluntarily. It is an essential part of the digestive system in keeping food between the teeth for chewing, the first part of the digestive process. Several other muscles have strength in different capacities that outweigh the strength of tongue.
According to the Library of Congress, the hardest working muscle is the heart. Each heartbeat propels another 2 ounces of blood through the body. On a daily basis, the heart pumps a minimum of 2,500 gallons of blood. It has the ability to contract over 3 billion times in a person's life.
Based on its weight, the masseter is the strongest muscle. This jaw muscle works with others in its group to close the teeth, creating forces of up to 55 pounds on the incisors and 200 pounds on the molars, says the Library of Congress.
The gluteus maximus is the largest muscle in the human body, according to the Library of Congress. It has the responsibility of keeping the body erect. It works against the forces of gravity and aids in walking.