Which muscle acts as the antagonist to the gastrocnemius during plantar flexion?

• A. Tibialis Anterior
• B. Soleus
• C. Plantaris
• D. Popliteus

Answer: (A)

This question hinges on how opposing actions at a joint are balanced. Plantar flexion—pointing the foot downward toward the sole—is mainly produced by the calf muscles, especially the gastrocnemius (and the soleus). The muscle that opposes that motion is the one that dorsiflexes the ankle, lifting the front of the foot toward the shin. That primary dorsiflexor is the tibialis anterior, which runs along the front of the shin and pulls the foot upward.

So, the tibialis anterior is the antagonist to the gastrocnemius during plantar flexion because it performs the opposite movement at the ankle. The soleus and gastrocnemius work together to plantarflex, not oppose it, with the plantaris playing a minor assistive role. The popliteus isn’t involved in opposing plantar flexion at the ankle; it helps with knee rotation and unlocking the knee.