What is the primary action of the quadriceps femoris muscle group at the knee joint?

• A. Extension of the forearm at the elbow
• B. Plantar flexion of the foot at the ankle
• C. Extension of the leg at the knee
• D. Flexion of the leg at the knee

Answer: (C)

Verified step by step guidance

1. Identify the anatomical location and function of the quadriceps femoris muscle group. This group is located in the anterior compartment of the thigh.
2. Recall that the quadriceps femoris is primarily responsible for movements involving the knee joint, not the elbow or ankle.
3. Understand that the quadriceps femoris muscle group acts to straighten the leg at the knee joint, which is known as extension.
4. Eliminate options that involve other joints or movements, such as extension of the forearm at the elbow or plantar flexion of the foot at the ankle, since these are controlled by different muscle groups.
5. Conclude that the primary action of the quadriceps femoris muscle group at the knee joint is extension of the leg.