The Popliteus Muscle
Anatomy and supply
The popliteus muscle is a small muscle located at the knee joint. 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).
A general task of the popliteus muscle is to stabilize the dorsal knee region. By its inward rotation of the knee joint it is responsible for reversing the so-called terminal rotation. This refers to the “locking” of the tibia and femur during the knee extension by a slight outward rotation (about 5°). 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.
The popliteus muscle may be injured in the scope of a rupture of the anterior cruciate ligament or damages involving the lateral meniscus. In contrast an isolated damage of the muscle is rather rare. Clinically the affected patients present with an unnatural outward rotation of the tibia when bending the knee. Additionally other general symptoms often occur such as muscle swelling, edema or bleeding.