Structure of the feet

The human foot consists of 26 bones in total:

• 7 tarsals (at the back of the foot)
• 5 metatarsals (in the middle of the foot)
• 14 phalanges (in the toes)

They are all connected to one another by joints, tendons and ligaments. The foot can be divided into three sections based on the different joints. These sections are called the tarsus (including the ankle), the metatarsus and the toes.

The ankle connects the bones in the lower leg to the bones of the foot. It can be divided into two parts: the upper and lower ankle.

The seven tarsal bones are held together tightly by ligaments, and are more or less fixed in place. They are grouped in two rows – one with three bones and one with four. One of these bones – the ankle bone (talus) – forms part of the upper ankle joint along with the shinbone (tibia) and calf bone (fibula). The shin and calf bones are separated from the ankle bone by a layer of cartilage. The ankle bone is also connected to the tarsal bones and the heel bone. The lower ankle joint is found between the heel bone, ankle bone and navicular bone.

The upper ankle allows you to move your feet upwards, downwards, and a little to the side. The lower ankle connects the ankle bone to the bones in the tarsus and the heel bone. It doesn't move as much as the upper ankle. The lower ankle only allows you to tilt your feet sideways slightly and turn them inward and outward.

The second row of tarsals is connected to the metatarsus. This consists of five long bones. You can feel them quite clearly along the top of your foot. The metatarsal bones leading up to the big toe and the bone at the base of the big toe come together to form a saddle joint, which gives the big toes its particular flexibility.

The five toes can move freely. Each toe has three bones – apart from the big toe, which only has two. They also have three joints: at the base, in the middle and towards the end of the toe. The base joints are ball-and-socket joints, which allow you to move your toes up and down, and to spread them out a little too. The middle joints are hinge joints and can only move in one direction: They can only bend or stretch the toes.

For your feet to stay supple and protect the sensitive muscles, tendons, blood vessels and nerves inside them, they have to be able to absorb impact. Normally, the soles of the feet do this job by forming a kind of arch between the heel and ball of the foot instead of resting flat on the ground.

The feet each have a longitudinal arch (along the length of the foot) and a transverse arch (from one side to the other). Muscles stretched along and across the foot pull the bones together to create an arch that is constantly under tension. When the foot has to carry a load – for instance, when you take a step – the muscles loosen slightly, allowing the arch to absorb the weight of your body. In a healthy foot, only the heel, ball of the foot and toes are in contact with the ground. A layer of fat beneath them provides protection. The metatarsus is given extra protection by a thick band of connective tissue called the “plantar fascia.” This tissue plays an important role in walking and standing, and tightens when the foot is placed on the ground.

There are more than 30 muscles in each foot. The feet are also moved by muscles in your lower leg known as extensor and flexor muscles. The thin tendons of these muscles run down into the toes. The tendons of the extensor muscles run along the top of the foot to the ends of the toes. The flexor tendons start at the heel or run along the sole of the foot to the toes.

The short foot muscles are found between the metatarsal bones. They help you spread out, bend (flex) and stretch (extend) your toes, but their main task is to tighten the arch of the foot.

Unlike our fingers, our toes aren't very flexible. Apart from the big and little ones, it’s almost impossible to move them independently of one another. There are a number of flexor muscles along the sole of your feet that move the three middle toes at the same time, and another muscle along the top of your feet that stretches them.

Several muscles in the soles of your feet are mainly there to support the arches. They pull the foot into an arch shape by pulling the forefoot and tarsus together. Most of these muscles run along the length of the foot because they also bend the toes. They create the arch between the front and back of the foot. The arch that goes from one side of the foot to the other is mainly supported by the muscle that’s responsible for pulling the big toe inward – the only muscle that doesn't run along the length of the foot.

When you raise your arch, the muscles in your foot are supported by the muscles and tendons in your lower leg.

Two main arteries supply blood to the foot: one at the top of the foot (dorsal artery) and one in the sole of the foot (plantar artery). The dorsal artery runs along the inner side of the top of the foot, along the big toe’s extensor muscle. It ends in an arch, from which other arteries branch off to supply blood to the upper side of your toes.

The plantar artery divides into two branches in the heel area. One runs along the inner side of your sole (medial plantar artery), the other in an arch shape on the outer side (lateral plantar artery). There are also arteries leading off from the lateral plantar artery into your toes. The arterial arches along the top and the sole of your foot are connected to one another.

The muscles and skin of the foot are supplied by three nerves:

• the deep peroneal nerve,
• the medial plantar nerve, and
• the lateral plantar nerve.

The deep peroneal nerve runs along the dorsal foot artery and moves the muscles that stretch your toes. One branch runs to a point between the big toe and the second toe, where it then splits into two other branches. The deep peroneal nerve also picks up sensory information from the skin along the top of the foot.

The medial (inner) and lateral (outer) plantar nerves run along the sole of your foot. The medial plantar nerve already splits near the heel, forming several branches along the sole of the foot. It moves the flexor muscles of your first three toes and, to a certain extent, the fourth one too. It also picks up skin sensations from the sole of your foot up to the fourth toe.

The lateral plantar nerve follows the lateral plantar artery up to the little toe. It moves some of the fourth toe’s flexor muscles and the little toe’s flexor muscle. It also picks up sensory information from the skin in this area and passes it on to your brain.