The rectus femoris muscle extends the leg at the:

• A. hip joint
• B. shoulder joint
• C. knee joint
• D. ankle joint

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by identifying the rectus femoris muscle. It is one of the four muscles that make up the quadriceps group, located in the anterior compartment of the thigh.
2. Step 2: Understand the primary function of the rectus femoris muscle. It is responsible for extending the leg at the knee joint and also assists in flexing the thigh at the hip joint.
3. Step 3: Analyze the options provided in the question. The rectus femoris does not act on the shoulder joint or the ankle joint, as these are unrelated to its anatomical location and function.
4. Step 4: Recall that the knee joint is the hinge joint where the quadriceps group, including the rectus femoris, exerts its action to extend the leg.
5. Step 5: Conclude that the correct answer is the knee joint, as this is the joint where the rectus femoris muscle performs its primary function of leg extension.