In Depth: Bones
The skeletal structure of the foot is similar to that of the hand but, because the foot bears more weight, it is stronger but less movable.
The bones of the foot are organized into the tarsal bones, metatarsal bones, and phalanges.
The foot begins at the lower end of the tibia and fibula, the two bones of the lower leg. At the base of those, a grouping of bones form the tarsals, which make up the ankle and upper portion of the foot.
The seven tarsal bones are:
- Calcaneus: The largest bone of the foot, it is commonly referred to as the heel of the foot. It points upward, while the remaining bones of the feet point downward.
- Talus: This irregularly shaped bone creates the lower portion of the ankle joint. It is the second largest bone in the foot.
- Cuboid: This multi-faceted bone sits on the outside of the foot near the fifth phalanx (little toe).
- Cuneiforms: These three small bones are closest to the five metatarsal bones. They sit in a row that begins at the inside of the foot, and moves toward the cuboid on the outside of the foot.
- Navicular: This curved bone sits between the talus and cuneiforms.
There are five metatarsal bones in each foot. Similar to the bones of the hand, these nearly parallel bones create the body of the foot. Numbered one through five, the bone that sits behind the big toe is number one, and the one behind the little toe is number five.
The phalanges create the toes. Each toe consists of three separate bones and two joints, except for the big toe, which has only two bones — distal and proximal phalanges — and one joint, like the thumb in the hand. The phalanges are made up of the distal phalanges at the tip, middle phalanges, and proximal phalanges, closest to the metatarsals.
Bones are connected via fibrous ligaments. A web of ligaments surrounds the ankle and other parts of the foot, and the metatarsal bones are strung together by ligaments to keep them from stretching too far apart. Each individual toe joint is wrapped in ligaments.
Because of its number of bones, the foot also contains numerous pieces of cartilage, a connective tissue that pads bones and joints. This cartilage can be damaged with excessive use or injury. Cartilage damage can cause joint pain.