The foot having to support the whole weight of the body, that weight is distributed among its component parts by the arrangement of two arches at right angles to one another-longitudinal and transverse.

Longitudinal Arch

The Longitudinal Arch consists of a solid stable pier posteriorly - the os calcis; and an elastic resilient pier anteriorly, which is much broadened out and consists of several parts, so that stability is not sacrificed to resilience. The summit, or roof, of the arch is the astragalus. The bones of the foot are really arranged in two longitudinal columns. The inner one consists of the os calcis, scaphoid, three cuneiforms, and first, second, and third metatarsals; the outer one consists of the os calcis, cuboid, and fourth and fifth metatarsals. In this way the weight is evenly distributed to the front of the foot, which is necessary in the upright position, as the line of gravity falls in front of the knee-joint. The arch is kept in shape by the plantar ligaments, plantar fascia, and tendon of tibalis posticus which act as ties.

Transverse Arch

The Transverse Arch is most marked at the tarso-metatarsal joints. The outer border of the foot is lower than the inner, so that when the two feet are placed side by side the transverse arch is complete.