What is the common name for the patella?

The common name for the patella is the kneecap.

The patella is a flat, rounded triangular bone at the front of the knee. It sits inside the quadriceps tendon and connects below to the patellar ligament, protecting the joint while helping the quadriceps muscles straighten the leg.

As a sesamoid bone, the patella is embedded within a tendon rather than forming a typical bone-to-bone connection. Its position improves the leverage of the quadriceps by holding the tendon farther away from the knee’s axis of rotation. That makes knee extension more efficient during walking, climbing, and jumping.

The patella articulates with the femur, or thigh bone—not directly with the tibia, shin bone. In humans it is the largest sesamoid bone. Babies initially have a cartilaginous patella, which begins turning into bone at about four years of age. The word patella comes from a Latin term for a shallow dish, describing its shape.