The skeleton of the foot and ankle begins with the ankle joint. The two bones of the lower leg, the large tibia and the smaller fibula come together at the ankle joint. The two bones that make up the hind foot are the talus and the calcaneus. The talus is connected to the calcaneus at the subtalar joint. The ankle joint allows the foot to bend up and down. The sub–talar joint allows the foot to rock from side to side.
Next in line is a group of bones, called tarsal bones, that work together as a group. These bones are very interesting in the way they fit together. When the foot is twisted in one direction by the muscles of the foot and leg, these bones lock together and form a very rigid structure. When they are twisted in the opposite direction, they become unlocked and allow the foot to conform to whatever surface the foot is contacting. The tarsal bones are connected to the five long bones of the foot called the metatarsals. There is a fairly rigid connection between the two groups without much movement at the joints.
Finally, there are the bones of the toes, the phalanges. The joints between the metatarsals and the first phalanx is called the metatarsal phalangeal joint. These joints form the ball of the foot, and movement in these joints is very important for a normal walking pattern. Not much motion occurs at the joints between the bones of the toes (phalanges). The big toe, or hallux is the most important toe for walking, and the first metatarsal phalangeal joint is a common area for problems in the foot.
Important Soft Tissues The main nerve to the foot (the posterior tibial nerve) enters the sole of the foot by running down behind the inside bump on the ankle, the medial malleolus. The main blood supply to the foot (the posterior tibial artery) runs right beside the nerve. There are other less important nerves and arteries that enter the foot from other directions. The large Achilles tendon is the most important tendon for walking, running and jumping. It attaches the calf muscles to the heel bone to allow us to raise up on the toes. The posterior tibial tendon attaches one of the smaller muscles of the calf to the underside of the foot. This tendon helps support the arch and allows us to turn the foot inward. The toes have tendons attached that bend the toes down (on the bottom of the toes) and straighten the toes (on the top of the toes). The anterior tibial tendon allows us to raise the foot.