Question

True about popliteus are all except?

• A. Flexor of knee
• B. Intracapsular origin
• C. Supplied by tibial nerve
• D. Causes locking of knee

Hint:

Popliteus is the muscle that reverses the screw-home mechanism.

Answer 1

The Correct Option is D

Step 1: The popliteus is a deep muscle of the posterior compartment of the leg. It arises from the lateral surface of the lateral condyle of the femur (origin is intracapsular) and from the outer margin of the lateral meniscus, and inserts on the posterior surface of the tibia above the soleal line.

Step 2: Its key action is to UNLOCK the fully extended knee. It does this by laterally rotating the femur on the fixed tibia, which initiates flexion. It is also an accessory flexor of the knee.

Step 3: So options (a) flexor of knee, (b) intracapsular origin, and (c) supplied by the tibial nerve are all correct statements about popliteus.

Step 4: The locking of the knee is produced by the quadriceps and medial rotation of the femur during terminal extension. Popliteus does the opposite - it unlocks the knee. Hence the false statement (the exception) is that it causes locking of the knee.