The human foot and ankle is a strong and complex mechanical structure containing more than 26 bones, 33 joints (20 of which are actively articulated), and more than a hundred muscles, tendons, and ligaments.
The foot can be subdivided into the hindfoot, the midfoot, and the forefoot:
The hindfoot is composed of the talus or ankle bone and the calcaneus or heel bone. The two long bones of the lower leg, the tibia and fibula, are connected to the top of the talus to form the ankle. Connected to the talus at the subtalar joint, the calcaneus, the largest bone of the foot, is cushioned inferiorly by a layer of fat.
The five irregular bones of the midfoot, the cuboid, navicular, and three cuneiform bones, form the arches of the foot which serves as a shock absorber.
The midfoot is connected to the hind- and fore-foot by muscles and the plantar fascia.
The forefoot is composed of five toes and the corresponding five proximal long bones forming the metatarsus. Similar to the fingers of the hand, the bones of the toes are called phalanges and the big toe has two phalanges while the other four toes have three phalanges.
The joints between the phalanges are called interphalangeal and those between the metatarsus and phalanges are called metatarsophalangeal (MTP).
Most of the motion of the foot is caused by the stronger muscles in the lower leg whose tendons connect in the foot. Contraction of the muscles in the leg is the main way that we move our feet to stand, walk, run, and jump.
There are numerous small muscles in the foot. Most of the muscles of the foot are arranged in layers on the sole of the foot. These muscles move the toes and provide padding underneath the sole of the foot.
Muscle system of the foot.
The main blood supply to the foot, the posterior tibial artery, runs right beside the nerve of the same name. Other less important arteries enter the foot from other directions. One of these arteries is the dorsalis pedis that runs down the top of the foot. You can feel your pulse where this artery runs in the middle of the top of the foot.
(Operative Techniques Foot & Ankle Surgery, SAUNDERS PUBLICATIONS)