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The patella (Latin: patella) is also known as the kneecap, and it is a flat movable bone covering the anterior aspect of the knee joint. It is embedded in the quadriceps femoris muscle tendon, and it is the largest sesamoid bone in the human body.

Human skeleton, Skeleton of the lower limb, Bones of lower extremity, Patella, Anterior view
Patella by

The patella is roughly triangular-shaped with three main parts:

  • Base
  • Apex
  • Articular surface


Base of patella

The base of the patella is the broad, superior border of the bone. The tendon of the quadriceps femoris muscle attaches to the base of the patella. The vastus intermedius of the muscle is attached to the base, while the vastus lateralis and vastus medialis attach to the outer and medial borders of the bone.

Skeleton of lower limb, Bones of lower extremity, Patella, Landmarks, Parts, Anterior view, Posterior view
Landmarks of patella by


Apex of patella

The apex of the patella is the pointed and most inferior portion of the bone. It gives attachment to the patellar ligament.


Articular surface

The articular surface is the cartilage-covered posterior upper part of the patella. It faces the femur and articulates with its patellar surface. The articular cartilage that covers the patella is among the thickest cartilages in the human body.