The patella is a sesamoid type of bone. A sesamoid bone is one that is embedded within a tendon. The patella is the largest sesamoid bone in the body and is embedded between the quadriceps and patellar tendons.
The patella is located between the femur and tibia. This bone, also known as the knee cap, is roughly triangular-shaped with the base facing up and the apex facing toward the feet. Although the patella provides protection to the knee joint, its primary function is to extend the leg. Other types of sesamoid bones are found in the hand, wrist, foot and neck joints.