Peroneus Tertius Muscle: Low Leg, Ankle, Heel Pain

The peroneus tertius muscle can cause and contribute to pain in the lower leg bend where the leg, ankle and foot connect. Pain is often felt on the outside of the heel. If your ankles are weak and have a tendency to buckle, you should check this muscle for trigger points and tightness. A classic sign of peroneus tertius dysfunction is pain worsens with each step.