Which muscles are the chief evertors of the foot?

• A. Tibialis posterior and flexor digitorum longus
• B. Fibularis longus and fibularis brevis
• C. Peroneus tertius and gastrocnemius
• D. Tibialis anterior and extensor digitorum longus

Answer: (B)

Eversion of the foot is produced mainly by the muscles in the lateral compartment of the leg, the fibularis (peroneal) group. The chief evertors are the fibularis longus and fibularis brevis. Their tendons run down the lateral leg, pass behind the lateral malleolus, and attach to the side of the foot (longus to the base of the 1st metatarsal and medial cuneiform; brevis to the tuberosity of the 5th metatarsal). When they contract, they pull the sole outward, turning the sole away from the midline. This action is opposed by the invertors, mainly the tibialis anterior and tibialis posterior, and the other movements of the foot involve different primary actions. The fibularis tertius can assist in eversion but is not the primary evertor, and other muscles listed primarily perform inversion, plantarflexion, or dorsiflexion rather than eversion.