There are plenty of ligaments and tendons which usually are very important with regard to providing strength to the arch with the foot. The principal 1 is called the posterior tibial muscle. This is a muscle in the deep calf which has a tendon that comes down the inside of the ankle joint and it’s action would be to support up the arch of the feet. There is a disorder called posterior tibial tendon dysfunction that is a problem with exactly how effectively the posterior tibial muscle can do its function. Any time the tibialis posterior muscle stops working as properly, a gradual flat feet develops as the other structures are not efficient at supporting upwards the actual mid-foot independently.