Which is the prime mover for ankle dorsiflexion?

Which is the prime mover for ankle dorsiflexion?

• A. Tibialis anterior
• B. Extensor hallucis longus
• C. Extensor digitorum longus
• D. Peroneus longus

Answer: (A)

When you bring the foot upward toward the shin, the primary driver is the muscle in the front of the leg that crosses the ankle joint. The tibialis anterior is the main dorsiflexor, and it also inverts the foot. It’s the strongest and most consistently active muscle for lifting the foot during walking and quick movements, which is why it’s the prime mover for ankle dorsiflexion. The other muscles listed can assist. Extensor digitorum longus and extensor hallucis longus cross the ankle and can contribute to dorsiflexion, especially when extending the toes, but they aren’t as powerful as the tibialis anterior. Peroneus longus sits on the lateral side, promoting plantarflexion and eversion rather than dorsiflexion, so it doesn’t serve as the primary dorsiflexor. In practical testing, you’d assess dorsiflexion by asking the patient to bring the top of the foot toward the shin and then apply resistance on the dorsum of the foot to gauge the tibialis anterior’s strength.

When you bring the foot upward toward the shin, the primary driver is the muscle in the front of the leg that crosses the ankle joint. The tibialis anterior is the main dorsiflexor, and it also inverts the foot. It’s the strongest and most consistently active muscle for lifting the foot during walking and quick movements, which is why it’s the prime mover for ankle dorsiflexion.

The other muscles listed can assist. Extensor digitorum longus and extensor hallucis longus cross the ankle and can contribute to dorsiflexion, especially when extending the toes, but they aren’t as powerful as the tibialis anterior. Peroneus longus sits on the lateral side, promoting plantarflexion and eversion rather than dorsiflexion, so it doesn’t serve as the primary dorsiflexor.

In practical testing, you’d assess dorsiflexion by asking the patient to bring the top of the foot toward the shin and then apply resistance on the dorsum of the foot to gauge the tibialis anterior’s strength.