Joints of the Lower Limb Flashcards

The knee joint's medial meniscus is more frequently injured than the lateral meniscus because:

Answer: It is firmly attached to the medial collateral ligament

The medial meniscus is attached to the medial collateral ligament, limiting its mobility and making it more susceptible to tearing with rotational forces.

The 'screw-home mechanism' of the knee involves which final movement when the knee reaches full extension?

Answer: Lateral rotation of the tibia on the femur

As the knee reaches full extension, the tibia rotates laterally (or femur medially) to lock the joint into a close-packed, stable position.

Which structure prevents posterior displacement of the tibia relative to the femur?

Answer: Posterior cruciate ligament

The posterior cruciate ligament (PCL) is the primary restraint against posterior tibial translation, preventing the tibia from sliding backward under the femur.

The suprapatellar bursa of the knee joint communicates with which structure?

Answer: The joint cavity itself

The suprapatellar bursa almost always communicates with the knee joint cavity, so joint effusions commonly extend into this bursa above the patella.

The oblique popliteal ligament at the knee is an expansion of which tendon?

Answer: Semimembranosus

The oblique popliteal ligament is a reflection of the semimembranosus tendon that reinforces the posterior knee capsule.

Which structure is responsible for 'unlocking' the fully extended knee to initiate flexion?

Answer: Popliteus muscle

The popliteus muscle medially rotates the femur on the fixed tibia (or laterally rotates the tibia) to unlock the screw-home mechanism and initiate knee flexion.

At the knee, which structure provides the primary static restraint against valgus (lateral) stress?

Answer: Medial collateral ligament

The medial collateral ligament is the primary static stabilizer resisting valgus stress (force pushing the knee inward), tested with the valgus stress test.