Which muscle is a primary mover in ankle dorsiflexion?

Which muscle is a primary mover in ankle dorsiflexion?

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

Answer: (C)

Dorsiflexion of the ankle is produced mainly by muscles in the front of the leg, with the tibialis anterior acting as the primary mover. This muscle runs from the upper lateral tibia and interosseous membrane to the medial cuneiform and the base of the first metatarsal, and its contraction lifts the front of the foot toward the shin while also helping invert the foot. The other two extensors contribute to dorsiflexion but their main jobs are toe extension: extensor hallucis longus extends the big toe (and assists dorsiflexion), and extensor digitorum longus extends the other toes (and also helps with dorsiflexion). The gastrocnemius, located in the back of the leg, mainly plantarflexes the ankle (and can assist knee flexion), so it isn’t the primary dorsiflexor.

Dorsiflexion of the ankle is produced mainly by muscles in the front of the leg, with the tibialis anterior acting as the primary mover. This muscle runs from the upper lateral tibia and interosseous membrane to the medial cuneiform and the base of the first metatarsal, and its contraction lifts the front of the foot toward the shin while also helping invert the foot.

The other two extensors contribute to dorsiflexion but their main jobs are toe extension: extensor hallucis longus extends the big toe (and assists dorsiflexion), and extensor digitorum longus extends the other toes (and also helps with dorsiflexion). The gastrocnemius, located in the back of the leg, mainly plantarflexes the ankle (and can assist knee flexion), so it isn’t the primary dorsiflexor.