Which muscle assists in foot inversion along with tibialis posterior?

• A. Tibialis anterior
• B. Fibularis longus
• C. Peroneus tertius
• D. Tibialis posterior

Answer: (A)

Foot inversion is turning the sole inward, a motion produced by muscles that pull the medial side of the foot upward. The tibialis posterior is a key inverter, and it works alongside another muscle that also inverts the foot. The tibialis anterior does just that: it helps invert the foot while also dorsiflexing the ankle. The other options either evert the foot (fibularis longus) or mainly assist with dorsiflexion and eversion (peroneus tertius), so they don’t fit the role of an inverter alongside tibialis posterior.