Which muscles are the primary plantar flexors of the ankle?

• A. Tibialis anterior
• B. Gastrocnemius and soleus
• C. Flexor digitorum longus
• D. Peroneus longus

Answer: (B)

Plantar flexion is driven mainly by the calf muscles—the gastrocnemius and the soleus. They connect to the heel via the Achilles tendon, and when they contract they pull the heel upward, producing that pointed-toe, push-off motion during standing, walking, and running. The gastrocnemius crosses both the knee and ankle, so it contributes more when the knee is extended, while the soleus lies behind it and provides strong ankle plantar flexion regardless of knee position. The other muscles listed don’t serve as the primary plantar flexors: tibialis anterior mainly dorsiflexes the ankle, flexor digitorum longus primarily flexes the toes (with some assistive plantar flexion), and peroneus longus mainly everts the foot with only a secondary plantar-flexion contribution.