Each foot is made up of 28 bones, 30 joints and more than 100 muscles, tendons and ligaments, all of which work together to provide support, balance and mobility. Here's a look at the main structures of the feet.
Bones
Nearly one-fourth of the body's bones are in our feet. The bones of the feet are:
- Talus – the bone on top of the foot that forms a joint with the two bones of the lower leg, the tibia and fibula.
- Calcaneus – the largest bone of the foot, which lies beneath the talus to form the heel bone.
- Tarsals – five irregularly shaped bones of the midfoot that form the foot's arch. The tarsal bones are the cuboid, navicular and medial, intermediate and lateral cuneiforms.
- Metatarsals – five bones (labeled one through five, starting with the big toe) that make up the forefoot.
- Phalanges (singular: phalanx) – the 14 bones that make up the toes. The big toe consists of two phalanges – the distal and proximal. The other toes have three.
- Sesamoids – two small, pea-shaped bones that lie beneath the head of the first metatarsal in the ball of the foot.
Joints
Joints in the feet are formed wherever two or more of these bones meet. Except for the big toe, each of the toes has three joints, which include:
- metatarsophalangeal joint (MCP) – the joint at the base of the toe
- proximal interphalangeal joint (PIP) – the joint in the middle of the toe
- distal phalangeal joint (DP) – the joint closest to the tip of the toe.
Each big toe has two joints:
- metatarsophalangeal joint
- interphalangeal joint
The surfaces of the bones where they meet to form joints are covered with a layer of cartilage, which allows them to glide smoothly against one another as they move. The joints are enclosed by a fibrous capsule that is lined with a thin membrane called the synovium, which secretes a fluid to lubricate the joints.
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