Which is the largest example of a sesamoid bone?

• A. Scapula
• B. Tibia
• C. Pisiform
• D. Patella

Answer: (D)

Sesamoid bones are bones that form within tendons to protect the tendon and improve mechanical efficiency by increasing the tendon’s leverage. The largest example is the patella, or kneecap, which sits inside the quadriceps tendon as it crosses the knee joint. Its big size allows it to act as a substantial fulcrum, increasing the moment arm of the quadriceps and enhancing knee extension strength while also reducing wear where the tendon glides over the femur. For comparison, the pisiform is a small sesamoid in the wrist, while scapula and tibia are not sesamoid bones.