Accessory bone that forms the knee cap is called:

The knee cap, also known as the patella, serves an important role in the knee joint's function and protection. It is classified as a sesamoid bone, which forms within the tendon of the quadriceps muscle. This bone protects the knee joint and improves the leverage that the tendon of the quadriceps muscle can exert on the femur, thereby enhancing the efficiency of the leg's movement.

The patella also acts as a shield for the knee joint, providing additional stability. It is essential for activities that involve bending and straightening the leg, such as walking, running, and jumping. Understanding the role of the patella helps in recognizing its significance in both anatomy and the biomechanics of the lower limb.