Location: Popliteus is found at the back of the knee
Action: Knee rotation and knee flexion
Origin: Popliteal groove on the lateral femoral condyle
Insertion: posterior surface of the tibia, above the soleal/popliteal line
Nerve Supply: Tibial branch of the sciatic nerve (L5)
Functions: Unlocks the knee at the start of flexion and helps protect the lateral meniscus
Popliteus is a triangular shaped muscle that is found deep in the popliteal fossa at the back of the knee, just below the joint.
It arises from the outer surface of the lateral femoral condyle, from within the joint capsule, below the lateral epicondyle and the superior attachment of the lateral collateral ligament. The stout tendon passes backwards, downwards and medially over the outer border of the lateral meniscus, to which it attaches. As the tendon leaves the joint capsule, fleshy fibers arise and continue downwards and medially attaching to a triangular area on the back of the tibia, just above the soleal (aka popliteal) line in a fan-like fashion.
The muscle has a very important role to play in the initial stages of knee flexion by laterally rotating the femur on the tibia to unlock the knee when the foot is on the floor e.g. standing. This movement allows the femoral condyle to glide forwards, releasing the ligaments and muscles from the knee’s close packed, extended position to allow full knee flexion. Additionally, if the foot is off the ground, it helps the medial hamstrings (semimembranosus and semitendinosus) to medially rotate the tibia.
Popliteus also attaches to the lateral meniscus, pulling it backwards slightly during knee flexion and rotation which helps to ensure the meniscus doesn’t get trapped between the moving bones. This may be one reason why the lateral meniscus is less prone to injury than the medial meniscus.
Popliteus minor is an additional small muscle, only present in a small percentage of individuals. It originates from the popliteal surface of the femur and attaches to posterior ligament of the knee.
Here are some other articles that you may find interesting:
1) Knee Muscles: Find out all about the different muscles of the knee, how they work together and what can go wrong
2) Pain Behind The Knee: Suffering from pain behind the knee? Find out what is wrong and how you can fix it
3) Knee Exercises: Loads of great strengthening and stretching exercises for the knee muscles