The kneecap
Patella · patella
A small floating bone at the front of the knee that gives your thigh muscles extra leverage.
What it does
The kneecap sits inside the tendon of the big quadriceps muscle at the front of your thigh. As your knee bends and straightens, it glides in a groove at the end of the femur. By holding the tendon away from the joint it acts like a pulley, making the muscle more effective at straightening the leg.
Surprising fact
Babies are born with a kneecap made of cartilage, and it usually doesn't start turning into bone until around the age of three to five.
Why it matters
Pain at the front of the knee when you climb stairs or squat often comes from how the kneecap tracks in its groove. Strengthening the thigh muscles is a common way to help it glide smoothly.
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Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.