Anatomy Exam Joints of the Lower Limb 3 — Questions and Answers
Question 1: The knee joint's medial meniscus is more frequently injured than the lateral meniscus because:
- It is firmly attached to the medial collateral ligament (Correct answer)
- It is thicker and less mobile
- It lacks a blood supply at its periphery
- It bears more body weight during gait
Correct 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.
Question 2: The 'screw-home mechanism' of the knee involves which final movement when the knee reaches full extension?
- Lateral rotation of the tibia on the femur (Correct answer)
- Medial rotation of the tibia on the femur
- Anterior translation of the tibia
- Posterior glide of the femoral condyles
Correct 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.
Question 3: Which structure prevents posterior displacement of the tibia relative to the femur?
- Posterior cruciate ligament (Correct answer)
- Anterior cruciate ligament
- Medial collateral ligament
- Arcuate ligament
Correct 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.
Question 4: The suprapatellar bursa of the knee joint communicates with which structure?
- The joint cavity itself (Correct answer)
- The prepatellar bursa
- The semimembranosus bursa
- The pes anserine bursa
Correct 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.
Question 5: The oblique popliteal ligament at the knee is an expansion of which tendon?
- Semimembranosus (Correct answer)
- Semitendinosus
- Biceps femoris
- Popliteus
Correct answer: Semimembranosus
The oblique popliteal ligament is a reflection of the semimembranosus tendon that reinforces the posterior knee capsule.
Question 6: Which structure is responsible for 'unlocking' the fully extended knee to initiate flexion?
- Popliteus muscle (Correct answer)
- Biceps femoris
- Gastrocnemius
- Plantaris
Correct 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.
Question 7: At the knee, which structure provides the primary static restraint against valgus (lateral) stress?
- Medial collateral ligament (Correct answer)
- Lateral collateral ligament
- Anterior cruciate ligament
- Iliotibial tract
Correct 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.
Anatomy Exam Joints of the Lower Limb 3
The knee joint's medial meniscus is more frequently injured than the lateral meniscus because: