Which muscle is the primary calf muscle involved in plantar flexion?

• A. Rectus Abdominis
• B. Gastrocnemius
• C. Soleus
• D. Tibialis Posterior

Answer: (B)

Plantar flexion is when you point the toes downward at the ankle. The primary calf muscle driving this movement is the gastrocnemius, because it’s a large muscle that crosses both the knee and ankle joints. When the knee is straight, the gastrocnemius has the most leverage to push the foot downward, which you feel in actions like standing on tiptoe or pushing off during running. The soleus also helps with plantar flexion, especially when the knee is bent, but it doesn’t provide as much force as the gastrocnemius in most common movements. Tibialis posterior can assist a bit but isn’t the main plantar flexor, and the rectus abdominis isn’t involved in ankle movement.