The Patella is the largest sesamoid bone in the body, and is formed in the tendon of the quadriceps extensor in front of the knee-joint. It is triangular in shape, with the apex downwards. The anterior surface of the bone is slightly convex. The posterior surface is much more rounded, and has a ridge which divides it into two parts longitudinally, of which the inner one is the smaller. This ridge glides between the two condyles of the femur.

Ossification

The patella does not begin to ossify till about the third year, and is complete at puberty.