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What is the Normal Anatomy of the Foot and Ankle?

The foot and ankle form complex joints that are involved in movement and providing stability and balance to the body. The foot and ankle consist of 26 bones, 33 joints, and many muscles, tendons, and ligaments.

Bones of the Ankle

The ankle joint connects the leg with the foot and is composed of three bones: the tibia, fibula, and talus. The tibia or shinbone and fibula or calf bone are bones of the lower leg, which articulate with the talus or ankle bone, enabling up and down movement of the foot.

Three bony bumps present on the ends of the tibia and fibula form parts of the ankle joint:

  • The medial malleolus, formed by the tibia, is found on the inside of the ankle.
  • The posterior malleolus, also formed by the tibia, is found at the back of the ankle.
  • The lateral malleolus, formed by the fibula, is found on the outer aspect of the ankle.

Bones of the Feet

The foot acts as a single functional unit, but can be divided into three parts: the hindfoot, midfoot and forefoot.

The hindfoot forms the ankle and heel, and is made up of the talus bone and calcaneus or heel bone. The heel bone is the largest bone in the foot.

The midfoot connects the hindfoot to the forefoot, and consists of one navicular bone, one cuboid bone, and three cuneiform bones. The navicular bone is found in front of the heel bone, and the cuneiform and cuboid bones are arranged in front of the navicular bone.

These bones are connected to five metatarsal bones of the forefoot that form the arch of the foot for shock absorption while walking or running. The forefoot is also made up of the toes or digits, formed by bones called phalanges - three in each toe, except the big toe, which has only two phalanges. The big toe has two additional tiny round sesamoid bones in the ball of the foot, which helps in upward and downward movements of the toe.

Ankle and Foot Joints

There are 33 joints in the ankle and foot. They include:

  • Hinge joints in the ankle, which allow flexion (bending) and extension
  • Gliding joints found in the hindfoot, which allow gliding movements
  • Condyloid joints found in the forefoot and toes, which allow the flexion (bending) and extension, adduction, and abduction (sideward movement).

The joints of the foot and ankle provide stability and support the weight of your body, helping you to walk or run, and adapt to uneven grounds.

Soft Tissues of the Ankle and Foot

Our feet and ankle bones are held in place and supported by various soft tissues such as cartilage, ligaments, muscles, tendons, and bursae.

The joint surface of all the bones of the ankle and foot are lined by a thin, tough, flexible, and slippery surface called the articular cartilage, which acts as a shock absorber and cushion to reduce friction between the bones. The cartilage is lubricated by synovial fluid, which further enables smooth movement of the bones.

Ligaments are tough rope-like tissue that connect bones to other bones, and hold them in place, providing stability to the joints. The plantar fascia is the largest ligament in the foot, originating from the heel bone to the forefoot, it extends along the lower side of the foot and is involved in maintaining the arch of the foot. The plantar fascia ligament stretches and contracts to provide balance and strength to the foot. Lateral ligaments on the outside of the foot and medial ligaments on the inside of the foot provide stability and allow up and down movement of the foot.

The foot is made up of 20 muscles that help in movement. The main muscles include:

  • Anterior tibial muscle, which allows up and down movement of the foot
  • Posterior tibial muscle, which supports the arch
  • Peroneal tibial muscle, which controls movement on the outside of the ankle
  • Extensors, which enable the ankle to raise the toes just before stepping forward
  • Flexors, which stabilize the toes against the floor
  • Smaller muscles that help the toes to lift and curl

Tendons are soft tissues that connect muscles to bones. The largest and strongest tendon in the foot is the Achilles tendon, present at the back of the lower leg around the heel bone. Other tendons include peroneal and anterior and posterior tibialis.

Bursae are small fluid-filled sacs that decrease friction between tendons and bone or skin. They contain special cells called synovial cells that secrete a lubricating fluid.

  • Inflammation of the Achilles tendon is known as Achilles tendinitis or tendonitis.
    The Achilles tendon is a tough band of fibrous tissue that runs down the back of your lower leg and connects your calf muscle to your heel bone.

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  • The Achilles tendon is a strong fibrous cord present behind the ankle that connects the calf muscles to the heel bone. It is used when you walk, run and jump.

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  • Achilles tendinitis is the inflammation and irritation to the Achilles tendon, a strong fibrous cord present behind the ankle that connects your calf muscles to the heel bone.

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  • Ankle injuries are very common in athletes and individuals performing physical work; often resulting in severe pain and impaired mobility. Pain after ankle injuries can either be from a torn ligament (ankle sprain) or broken bone (ankle fracture).

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  • The joints of the ankle are held in place and stabilized by strong bands of tissue called ligaments. Ankle instability is a chronic condition characterized by a recurrent slipping of the outer side of the ankle.co

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  • Charcot foot and ankle is a condition characterized by gradual weakening of the bones, joints and soft tissues, and loss of sensation in the foot and ankle. It is caused by nerve damage (neuropathy) in the foot and ankle or due to diabetes.

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  • Diabetes is a chronic condition that is characterized by high blood glucose (sugar) levels. Diabetic patients are at high risk for developing chronic wounds, especially in the feet.

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  • Flatfoot, also known as “fallen arches” or Pes planus, is a deformity in children’s feet where the arch that runs along the sole of the foot collapses to the ground or is not formed at all.

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  • Arthritis is the inflammation of joints as a result of degeneration of the smooth cartilage that lines the ends of bones in a joint. This degeneration of the cartilages leads to painful rubbing of the bones, swelling, and stiffness in the joints, resulting in restricted movements.

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  • Foot and ankle trauma refers to injuries that most commonly occur during sports, exercise or any other physical activity. Trauma may be a result of accidents, poor training practices or use of improper gear.

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  • Foot drop, also known as drop foot, is a sign of an underlying muscular, neurological or anatomical condition, where you are unable to lift the front part of your foot, which results in the dragging of the foot.

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  • Foot infections may occur after trauma to the foot or loss of tissue because of contamination from foreign material and/or bacteria or fungus. Infections can occur in healthy individuals as well as in those whose health is compromised.

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  • Rheumatoid arthritis is an auto-immune disease in which the body’s immune system (the body’s way of fighting infection) attacks its own healthy joints, tissues, and organs. It can cause pain, stiffness, swelling, and loss of function in joints.

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  • Forefoot pain, also referred to as metatarsalgia, is a type of pain that occurs in the ball of the foot (along the ends of the metatarsal bones). Generally, forefoot pain is associated with aging.

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  • A ganglion is a round, sac-like swelling or a fluid-filled lump under the skin near your foot and ankle joint. It can become bigger or smaller over time and may be visible or not, especially if it is small.

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  • A hammertoe is a deformity of a lesser toe (second through fifth toes), where the toe is bent upward at the toe’s middle joint, resembling a hammer. The bent portion may rub against the shoe causing pain, irritation and develop corns.

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  • The Lisfranc joint or tarsometatarsal joint refers to the region in the middle of the foot. It is a junction between the tarsal bones (bones in the foot arch) and metatarsal bones (five long bones in the foot).

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  • The tarsometatarsal joint or Lisfranc joint is the region in the middle of the foot formed by the articulation of the tarsal bones (a cluster of seven bones) and metatarsal bones (a group of five long bones).

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  • Midfoot arthritis is pain and inflammation of the midfoot. It occurs due to damage of cartilage or tissues around the joints. The damage may occur due to injury, aging or autoimmunity.

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  • Morton’s neuroma refers to a nerve injury that occurs between the toes, usually the third and fourth toes. This causes pain and thickening of the nerve tissue.

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  • The ankle joint is formed by the articulation of the end of the tibia and fibula (shinbones) with the talus (heel bone). Osteochondral injuries, also called osteochondritis dissecans, are injuries to the talus bone.

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  • The tibia and the fibula bones of the lower leg join with the talus bone to form the ankle joint. The talus bone is an important bone located between the tibia and fibula and the heel bone (calcaneus).

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  • Plantar fasciitis refers to the inflammation of the plantar fascia, a thick band of tissue that is present at the bottom of the foot. It runs from the heel bone to the toes and forms the arch of your foot.

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  • The posterior tibial tendon passes through the ankle to attach the calf muscle with the bones of the midfoot. It provides stability to the arch and supports the foot while walking.

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  • Sesamoids are two small, pea-shaped bones located in the ball beneath the big toe joint at the bottom of the foot. Sesamoid bones are connected to muscles and other bones by tendons that envelop these bones.

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  • A stiff big toe, also called hallux rigidus, is a form of degenerative arthritis affecting the joint where the big toe (hallux) attaches to the foot. The toe typically becomes stiff at the base and is sometimes called a “frozen joint”.

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  • A stress fracture is described as a small crack in the bone which occurs from an overuse injury of a bone. It commonly develops in the weight-bearing bones of the lower leg and foot.

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  • The talus is a small bone at the ankle joint that connects the heel bone and the shinbones, enabling up and down movement of the foot.

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  • The tarsal tunnel is a narrow passageway that lies on the inside of your ankle and runs into the foot. It encloses arteries, veins, tendons and nerves that supply the foot.

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  • American Academy of Orthopaedic Surgeons
  • Arthroscopy Association of North America
  • American Orthopaedic Association
  • South Carolina Orthopedic Association