Peroneal tendons
The lateral compartment of the leg is occupied by two peroneal muscles - peroneus longus and peroneus brevis. Peroneus longus occupies a more superior location in the lateral leg than does peronus brevis. Its origin is the head of the fibula and the upper 2/3 of the lateral fibular shaft. The tendon of peronus longus passes across the lateral malleolar groove, inferior to the peroneal trochlea and along the lateral side of the cuboid, across the peroneal notch and groove to insert onto the plantar aspect of the medial cuneiform and first metatarsal. Peroneus longus acts to evert the foot and plantar flex the ankle, as well as support the longitudinal arches of the foot. Peroneus longus is best identified by asking your subject to evert their foot and slightly plantarflex against resistance. The tendon will then become most evident as it passes across the lateral malleolar groove and the lateral surface of the calcaneus.
Peroneus brevis originates from the lower 2/3 of the lateral shaft of the fibula. The passage of its tendon across the ankle and lateral foot is similar to that of peronus longus, although with a few important differences. The tendon of peroneus brevis also passes across the lateral malleolar groove, but instead of passing inferiorly to the peroneal trochlea, it passes superiorly. The tendon then inserts into the lateral surface of the styloid process of the fifth metatarsal. Its action once again is to evert the foot and plantarflex the ankle, so placing your subjects foot in the same position as for peroneus longus will also aid in identification of this muscle and its tendon. Note that the muscle belly of peroneus brevis will be located posterior to the tendon of peroneus longus, superior to the lateral malleolus.