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The foot is an incredibly complex mechanism. This introduction to the anatomy of the foot and ankle will not be exhaustive but will highlight the structures that will be discussed in the sections that follow.

Bones and Joints

The skeleton of the foot and ankle begins with the ankle joint itself. The two bones of the lower leg, the large tibia and the smaller fibula, come together at the ankle joint to form a very stable mortise and tenon-type joint.

The mortise and tenon construct is well known to carpenters and craftsmen who use this joint in the construction of everything from furniture to large buildings. The construct is very stable!

The two bones that make up the hindfoot are the talus and the calcaneus. The talus is connected to the calcaneus at the subtalar joint. (Figure 1: picture of the hindfoot bone) The ankle joint allows the foot to bend up and down. The subtalar joint allows the foot to rock from side to side. (Figure 2: picture of hindfoot motion)

Next in line is a group of bones, called the tarsal bones, that work together as a group. These bones are very interesting in the way they fit together. When the foot is twisted 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 surfaces the foot is contacting.

The tarsal bones are connected to the 5 long bones of the foot called the metatarsals. There is a fairly rigid connection between the two groups without much movement at the joints. (Figure 3: picture of midfoot bones)

Finally, there are the bones of the toes, the phalanges. The joints between the metatarsals and the first phalanx are called the metatarsophalangeal joints. These joints form the ball of the foot and movement in these joints is very important for a normal walking pattern. (Figure 4: picture of toe bones)

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 metatarsophalangeal joint is a common area for problems.

Important Soft Tissue

The important soft tissues of the foot and ankle include ligaments, tendons, nerves, and blood vessels.

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 the 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 rise 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. This tendon, along with the peroneal tendon on the outer border of foot, acts very much like the reins of a bridle to keep a horse’s head straight. The ties 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. (Figure 5: picture of Achilles, posterior tibial tendon, and anterior tibial tendon).