It is the deepest muscle of the deep posterior compartment of the lower leg. Origin – posterior tibia, fibula, and interosseous membrane Insertion - navicular and adjacent tarsals and metatarsals on the plantar surface. Nerve supply – tibial nerve(l5,s1) Blood supply- posterior tibial artery Action- inversion of the foot, assist plantarflexion of the ankle Palpation- tendon palpated on medial malleolus during active inversion of the foot.belly is deep to triceps sural and cannot be palpated. “it is the key stabilizing muscle of the lower leg"