Foot Anatomy and Common Foot Problems

The parts of the foot and its functions are unique but can also contribute to common foot problems. The many bones, ligaments, and tendons of the foot help you move, but they can also be injured and limit your mobility. 

This article will give an overview of foot anatomy and foot problems that come from overuse, injury, and normal wear and tear of the foot.

Foot Anatomy

There are many parts of the foot and all have important jobs. Each foot has 26 bones, over 30 joints, and more than 100 muscles, ligaments, and tendons. These structures work together to carry out two main functions:

• Bearing weight
• Forward movement (propulsion)

The foot must be flexible to adapt to uneven surfaces and remain stable when you’re walking. 

The foot has three parts: the forefoot, midfoot, and hindfoot. There are bones, joints, muscles, tendons, and ligaments in each of these sections.

Bones

There are 26 bones in the foot, and they can be categorized according to their location.

Forefoot Bones

The forefoot bones include long bones in the middle of the foot as well as smaller toe bones.

• Phalanges: These are the toes. They are made up of a total of 14 bones: two for the big toe and three for each of the other four toes.
• Metatarsals: These are five long bones that go out from the base of each toe to the midfoot. The first metatarsal bone leads to the big toe and plays an important role in forward movement. The second, third, and fourth metatarsal bones provide stability to the forefoot.
• Sesamoid bones: These are two small, oval-shaped bones beneath the first metatarsal on the underside (plantar surface) of the foot. It is embedded in a tendon at the head of the bone (the part closest to the big toe). Its role is to reinforce and reduce stress on the tendon.

Midfoot Bones

The midfoot is made up of five irregularly shaped bones called the tarsals. The tarsals form the arch of the foot. The arch plays a key role in weight-bearing and foot stability.

The midfoot bones include:

• Navicular
• Cuboid
• Medial cuneiform
• Intermediate cuneiform
• Lateral cuneiform

Hindfoot

There are only two bones of the hindfoot, but they are the biggest bones in the foot.

• Calcaneus: This is the large bone at the heel of the foot (heel bone). Its main function is to transfer most of the body weight from the legs to the ground.
• Talus: This is the bone that sits between the calcaneus and the two bones of the lower leg (the tibia and fibula). It helps transfer weight and pressure across the ankle joint.

Joints

Joints are the part of the foot where two bones come together. While each foot has 30 joints, the following list gives a few examples.

Your big toe has two joints: 

• The metatarsophalangeal joint at the base of the toe and the interphalangeal joint just above it

The other four toes have three joints each:

• The metatarsophalangeal joint at the base of the toe
• The proximal interphalangeal joint in the middle of the toe
• The distal phalangeal joint near the tip of the toe

The midfoot has the tarsometatarsal joints (also called the Lisfranc joints), which connect the tarsal and metatarsal bones and provide stability to the arch of the foot.

The subtalar joint and the transverse tarsal joint are also important structures of the foot:

• The subtalar joint is where the calcaneus connects to the talus. 
• The transverse tarsal joint is what helps you turn your foot inward and outward (supinate and pronate) at the ankle. 

Muscles

The muscles that control the movements of the foot start in the lower leg and are attached to the bones in the foot with tendons.

These are the main muscles that facilitate movement in the foot:

• Tibialis posterior: The muscle that supports the arch of the foot
• Tibialis anterior: The muscle that allows the foot to move up
• Peroneus longus and brevis: The muscles that move the outside of the ankle
• Extensors: The muscles that raise the toes when stepping
• Flexors: The muscles that stabilize the toes and curl them under

Tendons

Tendons are fibrous connective tissues that attach muscles to bones. There are three major tendons that help with movement of the foot: forward bending of the foot (flexion) and backward bending of the foot (dorsiflexion):

• Achilles tendon: This is the most notable tendon of the foot that runs from the calf muscle to the heel. It is the strongest and largest tendon in the body that makes it possible to run, jump, climb stairs, and stand on your toes.
• Tibialis posterior: This tendon attaches the calf muscle to the bones on the inside of the foot and supports the arch of the foot.
• Tibialis anterior: This runs from the outer bone of the lower leg to the tarsals and first metatarsal, which enables dorsiflexion.

Ligaments

Ligaments are fibrous connective tissues that connect bone to bone. There are over 30 ligaments in the feet, but these are a few of the most important ones:

• Plantar fascia: This is the longest ligament of the foot that runs from the heel to the toes to form the arch. The plantar fascia provides strength for walking and assists with balance.
• Plantar calcaneonavicular: This is a ligament that connects the calcaneus to the talus. Its role is to support the head of the talus.
• Calcaneocuboid: This is the ligament that connects the calcaneus to the tarsal bones. It helps the plantar fascia support the arch of the foot.

Other ligaments in the foot include:

• Anterior talofibular ligament
• Calcaneofibular ligament
• Posterior talofibular ligament
• Deltoid ligament
• Spring ligament
• Lisfranc ligaments
• Inter-metatarsal ligaments
• Anterior inferior tibiofibular ligament

Nerves

The feet also have plenty of nerves that send and receive signals from the brain and help the structures move with walking, jumping, and other activities.

The main nerves of the foot come off the sciatic nerve:

• Tibial nerve: This nerve includes the medial plantar nerve and the lateral plantar nerve, which supply feeling to the sole of the foot. It also includes the sural nerve, which gives feeling to the outside of the foot.
• Peroneal nerve: This nerve includes the deep peroneal nerve and the superficial peroneal nerve, which provide feeling to the web space between the first and second toes as well as helps the ankle move. 
• Saphenous nerve: This nerve branches off the femoral nerve and provides feeling to the inside of the foot. 

Common Foot Problems

The average person has walked about 75,000 miles by the time they are 50 years old. Given how many moving parts the foot has it makes sense that it's very vulnerable to injury or overuse.

Some conditions specific to the foot can cause pain, less movement, or instability.

Plantar Fasciitis

Plantar fasciitis is caused by microtears in the thick fibrous tissue on the underside of the foot. It’s usually related to overstretching. Symptoms of plantar fasciitis include pain in the heel and arch that is often worse in the mornings. Plantar fasciitis is common in distance walkers or runners.

Bunions

A bunion is a bony protrusion on either the inside edge of the foot or the pinkie toe side. Bunions form gradually when the bones in the foot get misaligned, often from wearing shoes that don't fit or that squeeze the toes together tightly.

The big toe can bend so far inward that it crosses under or over the adjacent toe, causing a secondary misalignment called a hammertoe. Usually, a painful callous will form on top of the second toe.

Flat Feet

Pes planus (flat feet) is when the arc of the foot straightens out. It may spread so completely that the entire sole touches the floor.

Flat feet can cause pain in the midfoot area as well as swelling of the ankle and arch. The imbalance can also lead to hip, knee, or lower back pain.

Pes planus can be something you’re born with (congenital) but it’s often related to age or an injury. Between 20% and 30% of people have some degree of flat-footedness.

Heel Spurs

Since it’s the largest bone in the foot, the calcaneus (heel) is easily injured by problems with your gait (faulty foot biomechanics).

One of the more common problems is bony overgrowths (heel spurs) that cause severe pain when standing or walking. Also known as calcaneal spurs, heel spurs are most common in people who have plantar fasciitis, flat feet, or high arches.

Mallet Toe

If you have a mallet toe, the joint in the middle of the toe becomes permanently bent and points downward. Mallet toes develop when there is an imbalance in the muscles, tendons, or ligaments that hold the bones straight.

Like with bunions and hammertoes, a mallet toe often happens if you’re wearing ill-fitting shoes. However, it can also be caused by trauma or some diseases.

Metatarsalgia

Metatarsalgia is pain under the ball of the foot. It’s often caused by pressure from high-heeled shoes or from conditions like arthritis, nerve compression, fractures, or tears in ligaments that support the ball of the foot.

Claw Toe

A claw toe is a deformity of the foot where the toe bends downward from the middle joints. Sometimes, it will even curl under the foot entirely. Callouses or corns will form on top of the claw toe. If a corn puts pressure on nerves in the foot, it can cause pain. There are many options for corn removal, including at-home options.

Morton's Neuroma

Morton’s neuroma is a common foot problem where compression on a nerve in the ball of the foot causes burning, tingling, and pain near the third and fourth toes. It can make you feel like you have a pebble in your shoe or on a fold in your sock. Wearing high heels is a common cause of Morton’s neuroma.

Other Causes

There are many other conditions that can cause foot pain, including:

• Injuries (e.g., sprains and strains, ruptured tendon or ligament, bone fractures, tendinitis)
• Arthritis (e.g., osteoarthritis or "wear-and-tear" arthritis, rheumatoid arthritis, gout)
• Chronic diseases (e.g., diabetes and diabetic neuropathy) 
• Infections (e.g., athlete's foot, toenail fungus [onychomycosis])

Diagnosis

To diagnose problems with the parts of the foot, a healthcare provider or a foot specialist (orthopedist) will look at your feet for signs of swelling, deformity, skin growth, or misalignment. They may also feel your foot to check for lumps and bumps, and try to move it around to see if it causes you discomfort. 

A provider will ask you about your symptoms and medical history. They will want to watch you walk around to see if there are any issues with the way you move (gait analysis).

Imaging can help diagnose the cause of your pain because it lets your provider see what’s happening with the structures that make up your foot’s anatomy.

Here are tests your provider may want to do: 

• X-ray: This standard imaging test uses low-level radiation to take pictures. It can pick up conditions like bone fractures, dislocations, or arthritis damage.
• Computed tomography (CT): This imaging technology combines multiple X-rays to create a more three-dimensional representation of the foot structure. Having more complete pictures can help your provider see your joints better. 
• Magnetic resonance imaging (MRI): This imaging technique uses a powerful magnet and radio waves to create highly detailed images without radiation. It is good at helping your provider see soft tissues like muscles and ligaments. 

Treatment

The treatment for a foot problem will depend on what part of the foot is involved and the underlying cause.

In the short term, many causes of foot pain are helped by taking over-the-counter painkillers such as Tylenol (acetaminophen), Advil (ibuprofen), or Aleve (naproxen). Severe or chronic problems that are causing pain (like arthritis) may require steroid injections to reduce joint inflammation or prescription pain relievers like Celebrex (celecoxib).

For foot problems caused by anatomical deformities, special inserts worn inside your shoes (orthotics) can help compensate for the problems and reduce pain. Standard versions are available in pharmacies, but often a doctor will order custom-made orthotics or custom-fitted shoes.

Physical therapy can improve the strength and flexibility of the feet and ankles.

Sometimes conditions like a displaced fracture, bunions, or hammertoe will require surgery if they are causing severe pain or disability.

Summary

The foot is a complex part of the body that is made up of many bones, joints, muscles, ligaments, and tendons. It can easily be injured, develop diseases, or get infections. Bunions, claw toes, flat feet, hammertoes, heel spurs, mallet toes, metatarsalgia, Morton's neuroma, and plantar fasciitis are a few examples of foot problems that commonly cause pain. 

A structural foot problem can be diagnosed with a physical exam, a review of your symptoms and medical history, a gait analysis, and an imaging test such as an X-ray, CT scan, or MRI scan.

The treatment for foot pain is based on the condition but can involve OTC or prescription painkillers, orthotics, custom-fitted shoes, physical therapy, or surgery.