The human foot is designed to provide flexibility and resiliency, while being able power human movement and withstand several tonnes of pressure. Controlling balance, mobility, and providing a base for support, the foot consists of 26 bones, 33 joints, over 100 muscles, tendons, and ligaments, as well as the network of blood vessels, skin, nerves and soft tissue that give the foot its shape, providing it with cellular regeneration capabilities and nourishment to the muscles contained within.
The human foot is composed of three parts: the forefoot, midfoot and hindfoot. The forefoot consists of all the five toes. Each toe (phalanx) consists of bones called phalanges, followed by connecting long bones known as metatarsals. They are connected to one another by the 5 phalangeal joints located at the ball of the foot. Each toe consists of 3 bones and 2 joints, excluding the big toe (hallux), which has 2 phalanges, 2 joints, and two tiny irregularly shaped sesamoid bones which give it extra mobility. The forefoot bears half of the person's total body weight, while also releiving the pressure placed on the ball of the foot.
Closer to the body, the midfoot consists of the five tarsal bones which together form the arch of the foot. The midfoot functions as a shock absorber, and is mainly connected to the forefoot and hindfoot by a ligament called the plantar fascia.
Connecting the midfoot to the ankle (talus) is the hindfoot, which provides a base of support. It is composed of three joints which link the midfoot to the ankle, which is in turn linked to the bones of the lower leg (tibia and fibula). The largest bone in the foot, the calcaneus, is connected to the talus in order to enable ankle rotation. Beneath the calcaneous lies a cushioning layer of fat.
Muscles, Tendons, and Ligaments
There are 5 main muscles in the foot, which provide for the bulk of its movement. These are the anterior tibial muscle, which is responsible for upward movement; the arch-supporting posterior tibial muscle; the peroneal tibial muscle, which controls ankle movement; the extensors, which initiate walking; and the flexors, which provide balance by stabilising the toes against the ground. There are also a few other small muscles which are responsible for the movements of the toes.
The foot also consists of several tendons to connect the muscles to the bones and joints, the largest and most notable of which is the Achilles' tendon, which runs along the length of the calf and inserts at the heel. This tendon allows the human body to run, jump, climb stairs, and stand on tiptoe.
There are also a number of ligaments holding the tendons in place and proving stability to the joints. The largest ligament in the foot is the plantar fascia which connects from the heel to the toes, forming the arch in the foot. This ligament is responsible for just about all human movement through its stretching and contracting, while also providing balance.