Human Anatomy - Kotsan I. Y. 2009

Skeleton of the Lower Limb
The Foot as a Whole

The human FOOT serves as a supporting, cushioning, and locomotory apparatus of the body. The Shock-absorbing function of the foot is associated with the presence of arches. The arched Structure OF THE foot is absent in all animals, including anthropoids, and is a characteristic feature of the human foot, which is a result of bipedalism. There are five longitudinal arches and one transverse arch. The arches are formed by interconnected tarsal and Metatarsal Bones. Each longitudinal arch begins at the calcaneal tuberosity, includes the Tarsal Bones, and ends at the HEAD of the corresponding metatarsal bone (Fig. 73). The sustentaculum tali also participates in The formation of the first (medial) arch. The longitudinal arches vary in height. The second arch is the highest, while the fifth is the lowest. The longitudinal arches, connecting at their anterior ends in a parabolic shape, form the transverse arch of the foot (Fig. 74). It is formed by the navicular, cuneiform, and cuboid bones. The arch-like structure of the foot in a living human is maintained through the specific shape of the bones, the strength of the ligaments (passive "ties" of the foot), and Muscle tone (active "ties").

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Fig. 73. Diagram of a Cytology/practical/54.html">Longitudinal section of the foot (the direction of the longitudinal arch of the foot is indicated by a bold line)

1 — calcaneus, 2 — talus, 3 — navicular bone, 4 — intermediate cuneiform bone, 5 — second metatarsal bone, 6 — Phalanges of the second toe.

Fig. 74. Diagram of The structure of the transverse arch of the foot (tarsal and metatarsal regions)

a — section through the tarsometatarsal joints, b — section through the metatarsal bones, 1 — cuboid bone, 2, 3, 4 — cuneiform bones, I—V — metatarsal bones

Depending on the prominence of the arches, the foot can be classified as normal, flat, or high-arched. Normal and high-arched feet possess significantly better shock-absorbing properties than flat feet. Flatfoot can be either congenital or acquired. Improperly fitted footwear, muscle fatigue, underdeveloped Muscles, weak ligamentous apparatus, and prolonged stress can all be causes of flatfoot.

When standing, the foot rests on the ground via the calcaneus and the heads of the metatarsal bones. On a plantar footprint, a normal foot exhibits a lateral isthmus connecting the area corresponding to the calcaneus with the region of the metatarsal heads (Fig. 75). In a high-arched foot, this connection—and consequently the support—is absent in the middle. Such a foot leaves imprints only with its anterior and posterior sections. A flat foot produces a continuous imprint without an arch in the middle section. Transitional forms also exist between these three foot shapes.

Fig. 75. Footprints

1 — high-arched foot, 2, 3 — normal foot, 4 — flat foot

A distinction must be made between anatomical and functional flatfoot. The first type of flatfoot is characterized by the foot maintaining good mobility in its individual joints. The second type of flatfoot is characterized by severely limited joint mobility. This is the so-called true flatfoot, which is implied when discussing the drawbacks of a flat foot as a supporting and shock-absorbing organ.