Which muscle is primarily responsible for allowing a person to stand on their tiptoes?

• A. Tibialis anterior
• B. Rectus femoris
• C. Biceps brachii
• D. Gastrocnemius

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the action described in the problem. Standing on tiptoes involves plantar flexion, which is the movement of pointing the toes downward and lifting the heel off the ground.
2. Step 2: Identify the muscle group responsible for plantar flexion. The primary muscles involved in this action are located in the posterior compartment of the lower leg, specifically the calf muscles.
3. Step 3: Focus on the gastrocnemius muscle. The gastrocnemius is a large, superficial muscle in the calf that plays a key role in plantar flexion. It works in conjunction with the soleus muscle to lift the heel during tiptoe standing.
4. Step 4: Eliminate the incorrect options. The tibialis anterior is responsible for dorsiflexion (lifting the toes upward), the rectus femoris is part of the quadriceps group and primarily extends the knee, and the biceps brachii is a muscle of the upper arm involved in elbow flexion.
5. Step 5: Conclude that the gastrocnemius is the correct answer because it is the primary muscle responsible for plantar flexion, allowing a person to stand on their tiptoes.