Popliteus muscle

Anatomy

It originates at the lateral condyle of the femur and the posterior horn of the lateral meniscus. From there it runs mediocaudally towards the tibia and inserts above the origin of the soleus muscle.

In the course it lies within a compact fascia between the popliteal fossa and the joint capsule secured by the arcuate popliteal ligament. The innervation is supplied by the tibial nerve (L5-S2).

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Function

A general task of the popliteus muscle is to stabilize the dorsal knee region.

During the knee extension, the slight outward rotation (about 5º) of the tibia on the femur locks the knee joint (the so-called terminal rotation). The popliteus muscle is responsible for reversing this terminal rotation:

• In open kinetic chain (i.e. the foot is not on the ground), the tibia is free to move. Therefore, the popliteus muscle acts on its insertion, inwardly rotating the tibia on the femur.
• In closed kinetic chain (i.e. the foot is on the ground), the tibia cannot rotate. In this case, the popliteus muscle will act on its origin, outwardly rotating the femur on the tibia.

Furthermore the muscle pulls the lateral meniscus dorsally during the knee bend thus preventing its entrapment. Even though the popliteus muscle anatomically ranks among the flexors of the thigh musculature its ability to flex the knee is truly negligible.