A small triangular bone embedded in the quadriceps tendon at the front of the knee, also called the patella.
Structure
The kneecap is a sesamoid bone, meaning it develops within a tendon. Its rear surface is covered in thick cartilage that glides over the lower end of the femur.
Function
By sitting in front of the joint axis, the kneecap holds the quadriceps tendon away from the femur. This increases the angle at which the tendon pulls on the tibia, boosting the strength of knee extension.
Clinical note
A direct blow to the front of the knee can fracture the kneecap, often requiring surgical fixation because the quadriceps pulls the fragments apart.
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Kneecap starts with K and ends with P. Browse other body parts along the same letter.
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