Sesamoid bones are small, round bones that are embedded within tendons. They help reduce friction and improve the mechanical advantage of muscles during movement. The most well-known sesamoid bone is the patella, or kneecap, which protects the knee joint and aids in leg extension. These bones can vary in number and size among individuals and are commonly found in areas of the body that experience significant stress, such as the hands and feet. In the foot, sesamoid bones are located beneath the big toe and assist in weight-bearing and balance during walking and running.