Which muscle group is primarily responsible for extension of the knee joint?

• A. Gastrocnemius
• B. Hamstring group
• C. Quadriceps femoris group
• D. Tibialis anterior

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the movement involved. Knee extension refers to the straightening of the knee joint, increasing the angle between the thigh and the lower leg.
2. Step 2: Identify the muscle groups listed and their primary actions. The gastrocnemius primarily acts on the ankle joint (plantarflexion) and assists in knee flexion, not extension.
3. Step 3: The hamstring group is mainly responsible for knee flexion and hip extension, so it does not extend the knee.
4. Step 4: The tibialis anterior is involved in dorsiflexion of the foot at the ankle, not knee movement.
5. Step 5: The quadriceps femoris group is the primary muscle group responsible for knee extension, as it contracts to straighten the knee joint.