Which muscle inverts the foot?

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

Answer: (C)

Inversion of the foot means turning the sole inward toward the midline. The muscle that most directly causes this action, especially when the foot is moving up (dorsiflexing), is the tibialis anterior. It runs along the front of the shin to the medial side of the foot (the first metatarsal and the medial cuneiform). When it contracts, it pulls the medial edge of the foot upward, producing inversion while also helping to dorsiflex the ankle.

The other options don’t match inversion as their primary action: the peroneus longus lies on the outside of the leg and tends to evert the foot; extensor digitorum longus primarily extends the toes and dorsiflexes the ankle (with only a minor inversion component); tibialis posterior does invert the foot as well, but its strongest effect is more pronounced when the foot is plantarflexed rather than in the usual dorsiflexion scenario.