Foot & Ankle Anatomy

The foot and ankle in the human body work together to provide balance, stability, movement and propulsion.

This complex anatomy consists of:

  • 26 bones
  • 33 joints
  • Muscles
  • Tendons
  • Ligaments
  • Blood vessels, nerves and soft tissues

In order to understand the conditions that affect the foot and ankle, it is important to understand its normal anatomy.

Ankle

The ankle consists of three bones attached by muscles, tendons and ligaments that connect the foot to the shin. The two bones of the lower leg called the tibia (shin bone) and the fibula articulate (connect) with the talus (ankle bone) which form the tibiotalar joint (ankle joint) allowing the foot to move up and down.

The bony protrusions that can be seen and felt on the ankle:

  • Lateral malleolus: protuberance on outer side of the ankle bone, formed by the end of the fibula.
  • Medial malleolus: protuberance on the inner side of the ankle bone, formed by the end of the tibia.

The foot can be divided into three anatomical sections called the hind foot, mid foot, and forefoot.

Hind foot

The hind foot consists of the talus bone and calcaneus bone (heel bone). The calcaneus bone is the largest bone in your foot while the talus bone is the highest bone in your foot.

The calcaneus bone joins the talus bone at the subtalar joint enabling the foot to rotate at the ankle. The hind foot connects to the mid-foot at the transverse tarsal joint.

Midfoot

The mid-foot contains five tarsal bones: the navicular bone, the cuboid bone and 3 cuneiform bones. It is connected to the forefoot and hind foot with muscles and ligaments. The main ligament is the plantar fascia ligament. The mid-foot forms the arch of your foot and acts as a shock absorber when walking or running. The mid-foot connects to the forefoot at the five tarsometatarsal joints.

Forefoot

The forefoot consists of five long metatarsal bones and five toe bones or phalanges. The metatarsals connect to the phalanges at the ball of the foot by joints called metatarsophalangeal joints. Each toe has 3 bones and 2 joints, while the big toe contains two phalange bones, two joints, and two tiny, round sesamoid bones that enable the toe to move up and down. Sesamoid bones are bones that develop inside of a tendon over a bony prominence. The first metatarsal bone connected to the big toe is the shortest and thickest of the metatarsals and is the location for the attachment of several tendons. The forefoot is important for its role in propulsion and weight-bearing.

Soft Tissue Anatomy

Our feet and ankle bones are held in place and supported by various soft tissues.

Cartilage: Shiny and smooth, cartilage allows smooth movement where two bones come in contact with each other.

Tendons: Tendons are soft tissues that connect muscles to bones to provide support. The Achilles tendon, also called the heel cord, is the largest and strongest tendon in the body. Located on the back of the lower leg it wraps around the calcaneus, or heel bone. When inflamed, it causes a very painful condition called Achilles tendonitis and can make walking almost impossible due to the pain.

Ligaments: Ligaments are strong rope-like tissues that connect bones to other bones, providing stability to the joints. The plantar fascia is the longest ligament in the foot, originating at the calcaneus and continuing along the bottom surface of the foot to the forefoot. It is responsible for maintaining the arch of the foot and provides shock absorption. A common cause of heel pain in adults, plantar fasciitis can occur when repetitive micro tears occur in the plantar fascia from overuse. Ankle sprains, the most commonly reported injury to the foot and ankle area, involve ligament strain, and usually occur to the talofibular ligament and the calcaneal-fibular ligament.

Muscles: Muscles are fibrous tissues that expand and contract to cause body movements. There are 20 muscles in the foot. Some of the major ones include the anterior tibial (allows upward movement of the foot), posterior tibial (supports the arch), peroneal tibial (allows movement outside of the ankle), extensors (help raise the toes in an attempt to step forward) and flexors (stabilize the toes against the ground). Smaller muscles enable the toes to lift and curl. Muscle strains usually occur from overuse and lack of warm up.

Bursae: Bursae are small fluid-filled sacs that decrease friction between tendons, ligaments, muscles, bone and skin. Bursae contain special fluid called synovial fluid, which when it becomes infected leads to a common painful condition known as Bursitis.

Biomechanics of Foot & Ankle

Biomechanics describes the way the body moves. The ankle joint permits two movements:

  • Plantar flexion: Pointing the foot downward. This movement is normally accompanied by inversion of the foot.
  • Dorsiflexion: Raising the foot upward. This movement is normally accompanied by eversion of the foot.

The foot (excluding the toes) also permits two movements:

  • Inversion: Turning the sole of the foot inward.
  • Eversion: Turning the sole of the foot outward

The toes allow four different movements:

  • Plantar flexion: Bending the toes towards the sole of the foot
  • Dorsiflexion: Bending the toes towards the top of the foot
  • Abduction: Spreading the toes apart
  • Adduction: Bringing the toes together
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