Popliteus is one of the deep muscles situated at the posterior aspect of the knee joint. It arises from the lateral surface of the lateral condyle of the femur within the fibrous capsule of the joint. The origin is slightly anteroinferior to the origin of the fibular collateral ligament. It passes obliquely, both inferiorly and medially, and on route attaches to the posterior surface of the lateral meniscus of the knee joint. Descending medially, it inserts broadly into the posterior shaft of the tibia above the soleal line.
The actions of popliteus at the knee joint are varied:
- tibia medially when the femur is fixed; this 'unlocks' the knee permitting a return to a more mobile state
- femur on the tibia when standing
- protection of the lateral meniscus; it retracts the meniscus posteriorly during flexion of the knee
Popliteus is innervated by the tibial nerve (L4-S1).