What are sesamoid bones primarily responsible for?

Sesamoid bones are primarily responsible for improving mechanical advantage in the musculoskeletal system. These small, often round bones are embedded within tendons and their main function is to reduce friction and protect the tendon from stress and wear. By altering the direction of the muscle's pull, sesamoid bones enhance the efficiency of force exerted by muscles, which contributes to improved leverage during movement.

For instance, the largest sesamoid bone in the human body is the patella (kneecap), which plays a crucial role in knee extension by serving as a fulcrum, thereby enhancing the mechanical advantage of the quadriceps muscle during activities such as running or jumping. This adaptation allows for more effective and powerful movements, highlighting the functional significance of sesamoid bones in biomechanics.