The human foot combines mechanical complexity and structural strength. The ankle serves as foundation, shock absorber and propulsion engine. The foot can sustain enormous pressure (several tons over the course of a one-mile run) and provides flexibility and resiliency.
The foot and ankle contain:
- 26 bones (One-quarter of the bones in the human body are in the feet.);
- 33 joints;
- more than 100 muscles, tendons and ligaments (Tendons are fibrous tissues that connect muscles to bones and ligaments are fibrous tissues that connect bones to other bones.); and a network of blood vessels, nerves, skin, and soft tissue.
These components work together to provide the body with support, balance, and mobility. A structural flaw or malfunction in any one part can result in the development of problems elsewhere in the body. Abnormalities in other parts of the body can also lead to problems in the feet.
- the anterior tibial, which enables the foot to move upward;
- the posterior tibial, which supports the arch;
- the peroneal tibial, which controls movement on the outside of the ankle;
- the extensors, which help the ankle raise the toes to initiate the act of stepping forward; and
- the flexors, which help stabilize the toes against the ground.
Smaller muscles enable the toes to lift and curl.
There are elastic tissues (tendons) in the foot that connect the muscles to the bones and joints. The largest and strongest tendon of the foot is the Achilles tendon, which extends from the calf muscle to the heel. Its strength and joint function facilitate running, jumping, walking up stairs, and raising the body onto the toes.
Ligaments hold the tendons in place and stabilize the joints. The longest of these, the plantar fascia, forms the arch on the sole of the foot from the heel to the toes. By stretching and contracting, it allows the arch to curve or flatten, providing balance and giving the foot strength to initiate the act of walking. Medial ligaments on the inside and lateral ligaments on outside of the foot provide stability and enable the foot to move up and down.
Skin, blood vessels, and nerves give the foot its shape and durability, provide cell regeneration and essential muscular nourishment, and control its varied movements.