What is a sesamoid bone?

A sesamoid bone is characterized as a free-floating bone that forms within a tendon or, in some cases, under a tendon. Its primary role is to provide support and withstand the pressure exerted during movement, particularly in areas where tendons could be under significant friction against other joints or bones. The best-known example of a sesamoid bone is the patella, or kneecap, which sits within the tendon of the quadriceps muscle and helps to increase the mechanical leverage of the tendon.

This unique positioning of sesamoid bones helps to elevate the tendon away from the joint, improving the efficiency of muscle contractions and protecting the tendon from stress and injury. Understanding the role and location of sesamoid bones is crucial in sports medicine, particularly when assessing injuries involving tendon and joint interactions.