Final answer:
The patella, or kneecap, is a sesamoid bone that increases leverage for the quadriceps femoris muscle, protects the tendon from friction, and supports the knee joint.
Step-by-step explanation:
The subject referred to in the question is the patella, also commonly known as the kneecap. The patella is formed within the tendon of the quadriceps femoris, the powerful muscle located at the front of the thigh. Its base is attached to the quadriceps femoris muscle, and its apex connects to the patellar ligaments.
As a sesamoid bone, it articulates with the patellar surface of the femur during knee movements, protecting the quadriceps tendon from friction against the distal femur. This unique structure increases the leverage of the quadriceps femoris muscle during leg extension at the knee and provides important support and stabilization for the knee joint.