The popliteus is a small triangular muscle at the back of the knee. It arises from the lateral femoral condyle and inserts on the posterior tibia above the soleal line. The tibial nerve supplies it, and it unlocks the fully extended knee by rotating the femur laterally on the tibia.
| Origin | Lateral surface of the lateral femoral condyle, by an intracapsular tendon. |
|---|---|
| Insertion | Posterior surface of the tibia above the soleal line. |
| Innervation | Tibial nerve (L4-S1). |
| Blood supply | Inferior medial genicular and posterior tibial arteries. |
| Action | Unlocks the knee at the start of flexion by laterally rotating the femur on a fixed tibia, or medially rotating the tibia when the foot is off the ground. |
3D model: BodyParts3D (CC BY 4.0), adult male reference anatomy. Highlighted structure shown with nearby bones for context.
The popliteus forms part of the floor of the popliteal fossa. Its tendon passes inside the knee joint capsule, beneath the lateral collateral ligament.
It unlocks the extended knee so that flexion can begin.
The tibial nerve.
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