Patella

Os patellae

The patella is a triangular sesamoid bone with a broad superior base and a pointed inferior apex. Its posterior surface articulates with the patellar surface of the femur. The anterior surface is roughened for the quadriceps tendon attachment.

Type Bone
Body System Skeletal
Body Region Thigh
Latin Name Os patellae
FMA ID 24485

Function

The largest sesamoid bone in the body, embedded within the quadriceps tendon. Increases the mechanical advantage of the quadriceps muscle by increasing the lever arm for knee extension.

Clinical Significance

Patellar fractures result from direct trauma or forceful quadriceps contraction. Patellar dislocation typically occurs laterally. Chondromalacia patellae (runner's knee) causes anterior knee pain from cartilage degeneration.

Frequently Asked Questions

What is the function of the patella?
The patella (kneecap) is a sesamoid bone embedded in the quadriceps tendon that improves the mechanical efficiency of knee extension. By increasing the moment arm of the quadriceps force, the patella reduces the muscle force required to extend the knee by approximately 33–50%. It also protects the anterior knee joint from direct trauma.
Where is the patella located?
The patella is located at the anterior aspect of the knee joint, within the quadriceps femoris tendon. Its posterior surface articulates with the femoral trochlea, forming the patellofemoral joint. Superiorly the quadriceps tendon attaches to it, and inferiorly the patellar tendon (ligament) connects it to the tibial tuberosity. It is the largest sesamoid bone in the human body.
What are common patella injuries?
Common patella injuries include patellar fractures (from direct impact or forceful quadriceps contraction), patellar dislocation (usually lateral, common in young females), and patellofemoral pain syndrome (runner's knee), characterized by anterior knee pain during activities like climbing stairs or squatting. Chondromalacia patellae refers to softening and deterioration of the patellar articular cartilage.

Related Structures

articular surface articular system joint system articulation joint Atlas (C1) Atlas attachment site axial skeleton plus cranial skeleton skeleton axiale Axis (C2) Axis bone collagen fibril

Medical Disclaimer

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Educational Disclaimer

This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for medical decisions.

Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.