Which is often called the strongest muscle in the human body, pound for pound?

The masseter, the muscle that closes the jaw and drives chewing, is often cited as the strongest muscle in the human body relative to its size, capable of clamping down with a force exceeding 90 kilograms on the molars in some people. Its compact size combined with the sheer force it generates makes it stand out compared to larger muscles elsewhere in the body when strength is measured pound for pound.

The heart and thigh muscles are both impressive, the heart for its tireless endurance and the thigh muscles for generating large absolute forces in walking and running, but neither matches the masseter's disproportionately high force relative to its small size.

This intense biting force is part of why teeth grinding, known as bruxism, can cause so much wear over time, since the masseter can generate pressures far beyond what everyday chewing actually needs.