Tibialis posterior
Tibialis posterior is an extremely important muscle which is responsible for inverting the foot and contributing to ankle joint plantar flexion. It is located in the deep posterior compartment of the leg, and thus, its muscle belly is difficult to palpate. Part of the muscle belly however, may be palpated by wrapping your fingers under the medial border of the tibia. The tendon is palpable as it passes across the medial malleolar groove and beneath the flexor retinaculum to the medial aspect of the foot. Place your subject's foot in an inverted and slightly plantarflexed position against resistance to place tension on the tendon. Bear in mind that the tibialis posterior has an extensive insertion including the navicular tuberosity, cuneiforms, lesser metatarsals and cuboid.