Human feet structure is formed by a set of different small bone arranged in a specific manner and acts like a tripod. Heel acts as one pod and forefoot acts as another two pods one at great toe and another at small toe. These two pods of fore foot connect with the pod at heel and form arch. Medial arch or border of foot from heel to great toe and lateral arch or border from heel to small toe. Medial arch or border remains off the ground and is a true arch where as lateral arch is a platform on which foot rests on ground with all three pods. Hight of the medial arch or border can be variable from very low to high. This arch helps in balancing, shock absorbing and gait propagation. Shape and height of the arch is not constant in every individuals. In some individual medial border or arch can be low and the whole sole of the foot will touch the ground and foot with heel will deviate towards outside. This type of foot is called flat foot or pes planus. Whereas in high medial arch most of the middle part of the foot will be off the ground leaving a narrow strip of lateral border touching the ground and the whole foot will deviate towards inside. This type of foot is called high arched footor cavus foot. 

Foot Arch Type