The foot is an intricate part of the body, consisting of 26 bones, 33 joints, 107 ligaments, and 19 muscles. Scientists group the bones of the foot into the phalanges, tarsal bones, and metatarsal bones.
The bones and joints in the feet experience wear and tear, so conditions that cause damage to the foot can directly affect its health.
This article outlines the basic anatomy of the foot bones, along with some of the most common conditions affecting these bones.
The human foot consists of 26 bones. These bones fall into three groups: the tarsal bones, metatarsal bones, and phalanges.
Image credit: Stephen Kelly, 2019
The tarsal bones are a group of seven bones that make up the rear section of the foot.
Tarsal bones include:
- The talus, or ankle bone: The talus is the bone at the top of the foot. It connects with the tibia and fibula bones of the lower leg.
- The calcaneus, or heel bone: The calcaneus is largest of the tarsal bones. It sits below the talus and plays an essential role in supporting body weight.
- The tarsals: These five bones form the arch of the midfoot. They are the medial, intermediate, and lateral cuneiforms, the cuboid, and the navicular.
The metatarsal bones are a group of five tubular bones in the middle of the foot. They connect to the tarsal bones and the phalanges.
The metatarsals sit in a row, and doctors number them one to five. The first one sits closest to the arch of the foot, and number five sits at the outer edge of the foot.
The phalanges are the bones in the toes. The second to fifth toes each contain three phalanges.
From the back of the foot to the front, doctors call them the proximal, middle, and distal phalanges.
The big toe or hallux contains only two phalanges, which are proximal and distal.
The metatarsal phalangeal joints are the joints between the metatarsals and the proximal phalanx of each toe. These joints form the ball of the foot.
The first metatarsal phalangeal joint sits in line with the big toe. It is a common area for foot pain and other problems.
Common conditions affecting the bones of the feet include:
Big toe arthritis
This type of arthritis is known as big toe arthritis. Doctors may refer to it as hallux limitus or hallux rigidus.
Big toe arthritis occurs when cartilage in the joint of the big toe begins to wear away. This can happen as a result of many years of repetitive upward movement of the joint.
Certain activities, such as prolonged running and walking, can increase a person’s risk of developing arthritis in this area.
Symptoms of big toe arthritis include:
- pain, stiffness, and swelling in the big toe
- a bone spur
- metatarsalgia, or pain and inflammation in the ball of the foot
A bunion is a prominent bump on the inside of the foot, near the base of the big toe.
Bunions develop when the bone at the base of the toe — the first metatarsal — begins to separate from the bone at the base of the second toe — the second metatarsal.
As the first metatarsal drifts outwards, it causes the big toe to drift toward the other toes. These processes cause the bunion to become more prominent.
A person with a bunion may experience pain and discomfort at the site of the bunion or underneath the ball of the foot. These symptoms may worsen when walking or standing.
People who develop bunions tend to compensate by carrying more weight on the second toe, which can cause calluses to develop.
Gout is a type of inflammatory arthritis. Although it can affect almost any joint in the body, it most commonly affects the joint at the base of the big toe.
Gout usually occurs due to a high concentration of uric acid in the blood.
Uric acid is a chemical that usually dissolves in the blood and leaves the body through the urine. In people with gout, excess uric acid begins to accumulate and form crystals in the joints.
Uric acid crystal deposits can trigger an extreme inflammatory reaction, which causes pain and swelling in the affected area.
A hammer toe is a condition that usually affects toes other than the big toe. Instead of pointing straight out in front, these toes point downward, forming a claw shape.
In most cases, the condition develops with age. It is usually the result of a muscle imbalance when the long muscles of the lower leg overpower the smaller muscles of the foot. This imbalance causes the toes to bend inward.
A hammer toe may cause the following symptoms:
- pain and calluses on the tops of the toes due to friction with shoes
- pain on the tips of the toes due to toes pressing into the sole of a shoe
- metatarsalgia, or pain in the joints at the base of the toes
- a sensation that feels like walking on marbles
Heel spurs and plantar fasciitis
Heel spurs are bony growths that develop on the heel bone, or calcaneus. Although they may cause some discomfort, they are rarely painful.
However, heel spurs often develop as a result of a condition called plantar fasciitis, which can cause pain.
Plantar fasciitis refers to inflammation and thickening of the plantar fascia, which is the ligament that supports the arch of the foot.
The following factors can increase the risk of developing plantar fasciitis:
- tight calf muscles that reduce the foot’s ability to flex upward
- a very high arch in the foot
- repetitive impact from some sports
Plantar fasciitis can cause pain in the heel or bottom of the foot when standing or walking.
People who develop heel spurs without plantar fasciitis are unlikely to experience painful symptoms.
Heel spurs affect up to one in 10 people. Of these, only half will experience any pain.
Sesamoiditis is inflammation of one or both sesamoid bones at the base of the big toe. The condition can cause significant pain in this area.
Excessive and repetitive weight on the big toe is the primary cause of sesamoiditis. Factors that increase the risk of sesamoiditis include a sudden increase in activity levels or a change in footwear.
People with sesamoiditis may experience the following symptoms:
- sharp and often severe pain at the base of the big toe
- pain and discomfort when walking barefoot or on hard surfaces
- walking with a limp
Stress fractures happen when an area of bone endures excessive and repetitive force.
Certain repetitive activities, such as walking and running, can cause microscopic cracks, or microfractures, to develop in the bone. Ordinarily, the body can repair these microfractures.
However, sometimes the body is unable to maintain the rate of repair required to keep up with the stress on the foot. When this happens, microfractures can develop into a stress fracture.
Stress fractures commonly affect the following bones:
- the base of the fifth metatarsal
- the sesamoids of the big toe
- the navicular bone
The main symptom of a stress fracture is aching pain in the affected area of the foot.
According to the American College of Foot and Ankle Surgeons, a person may wish to see a doctor if they experience any of the following:
- a foot injury, such as a sprain or broken toe
- changes in the appearance of the foot or ankle
- pain in the foot, ankle, or lower leg
- pain or discomfort after standing
- heel pain in the morning
- impaired ability to perform certain activities
- an abnormal growth on the foot
- a medical condition that can affect the feet, such as diabetes or arthritis
The anatomy of the foot is highly intricate, consisting of many bones, joints, and ligaments.
Some health conditions, injuries, and general wear and tear can all cause or contribute to conditions affecting foot bones.
People who experience persistent foot pain or notice changes in the appearance of their feet may wish to see a doctor.