leg. Other animals The fibularis tertius muscle in horses originates from the near the lateral condyle of the femur, passes through the extensor sulcus on the head of the tibia, and inserts onto the third metatarsal bone, the third and fourth tarsal bones, and the calcaneus. Rupture of the muscle may cause the Achilles tendon to have a slight dip. Additional images See also Fibularis muscles Fibularis longus Fibularis brevis References External links - "The Leg: Muscles" PTCentral Muscles of the lower limb