Patella (Kneecap)

What Does the Kneecap Do

The kneecap, commonly referred to as the patella, is the largest sesamoid bone in the body. Positioned in front of the knee joint, it serves as a protective cap. As a sesamoid bone, it is embedded within the quadriceps tendon.

Where Can the Kneecap Be Found

You can locate the kneecap by touching the knee. The bone you feel is the kneecap.

Anatomically, the kneecap is positioned between the femur of the upper leg and the tibia-fibula of the lower leg. Specifically, it is situated in front of the patellar surface, a groove between the condyles of the distal end of the femur.

Key Details

Type Sesamoid bone
Number in the human body 2 (1 in each knee)
Articulates with Femur
Kneecap X-ray


  • Shielding the knee joint from physical injury.
  • Facilitating smooth knee movement by acting as a pulley for the quadriceps tendon during flexion and extension of the lower leg. Positioned in front of the femoral condyles, it increases or decreases the angle at which the quadriceps tendon pulls the tibial shaft, thus extending or flexing the lower leg.

Structure of the Kneecap Region

The kneecap is a thick, flat, triangular bone with concave anterior and convex posterior surfaces. The posterior surface articulates with the femur and features two shallow depressions or facets, medial and lateral.

Being triangular, it has an apex and three sides—the medial border, lateral border, and superior border or base. On the lateral and medial borders of the kneecap, there are rough markings where vasti lateralis and medialis attach.

Labeled Kneecap Bone

Bony Landmarks and Articular Surfaces


The base is the blunt, broad, convex, nonarticular proximal end of the bone, opposite the apex. It serves as an attachment point for the quadriceps tendon.


The apex is the pointy, nonarticular tip of the bone, directing downwards. It serves as an attachment site for the patellar ligament, an inferior extension of the quadriceps tendon.

Lateral articular facet

It articulates with the lateral condyle of the femur.

Medial articular facet

It articulates with the medial condyle of the femur and is smaller than the lateral articular facet.

Common Questions

Q.1. Is the kneecap a short bone?

Ans. Yes, the kneecap is a short bone.

Q.2. What keeps the kneecap in place?

Ans. The patellar tendon and quadriceps tendon keep the kneecap in place.

Q.3. Is the kneecap a floating bone?

Ans. Yes, the kneecap is a floating bone as it does not directly articulate with other bones in the knee joint.

Q.4. Do infants have a kneecap or patella?

Ans. When they are born, infants have a cartilaginous kneecap that develops during fetal growth. This cartilage then gradually hardens and becomes the bony patella as they grow up.


    1. The Patella –
    2. Patella –
    3. Patella –
    4. Anatomy, Bony Pelvis and Lower Limb, Knee Patella –
    5. Patella –
Rate article
Add a comment