Foot & Ankle anatomy
The foot and ankle work together to provide balance, stability, movement, and propulsion.
This complex anatomy consists of:
- 26 bones
- 33 joints
- Blood vessels, nerves, and soft tissue
In order to understand conditions that affect the foot and ankle, it is important to understand the normal anatomy of the foot and ankle.
The ankle consists of three bones that, with their associated muscles, tendons, and ligaments, connect the foot to the leg. In the lower leg are two bones called the tibia and the fibula. These bones articulate (connect) to the talus at the tibiotalar joint (ankle joint) allowing the foot to move up and down.
- Tibia (shin bone)
- Lateral Malleolus
- Medial Malleolus
The bony protrusions that we can see and feel on the ankle are:
Lateral Malleolus: this is the outer ankle bone formed by the distal end of the fibula.
Medial Malleolus: this is the inner ankle bone formed by the distal end of the tibia.
The foot can be divided into three anatomical sections called the hind foot, mid foot, and forefoot. The hind foot consists of the talus and the calcaneus. The calcaneus joins the talus at the subtalar joint enabling the foot to rotate at the ankle.
The midfoot contains five tarsal bones: the navicular, the cuboid, and 3 cuneiforms. The midfoot is responsible for the arches of your feet and acts as a shock absorber when walking or running.
- Cuneiform Bones
The forefoot consists of your toe bones, called phalanges, and metatarsal bones, the long bones in your feet. Phalanges connect to metatarsals at the ball of the foot by joints called metatarsalphalngeal joints. Each toe has 3 phalange bones and 3 joints, while the big toe contains two phalange bones, two joints, and two small, round sesamoids that enable the toe to move up and down.
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 tissue that connects 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 attaches to the calcaneus, or heel bone. When inflamed it causes a very painful condition called Achilles tendonitis.
Ligaments: Ligaments connect bones to other bones, providing stability to the joints. Ankle sprains, the most commonly reported injury to the foot and ankle, involve ligament strain, and usually involves the talo-fibular and the calcaneal-fibular ligament.
Muscles: Muscles are connective tissue capable of contracting to cause body movement. There are various muscles in the foot and are classified as intrinsic or extrinsic. The intrinsic muscles are those located in the foot and are responsible for toe movement. The extrinsic muscles are located outside the foot in the lower leg. The gastrocnemius or calf muscle is the largest of these and assists with movement of the foot. Muscle strains occur usually from overuse of the muscle in which the muscle is stretched.
Bursae: Bursae are small fluid filled sacs that decrease friction between tendons and bone or skin. Bursae contain special cells called synovial cells that secrete a lubricating fluid. When this fluid becomes infected, a common painful condition known as bursitis can develop.
Biomechanics of Foot & Ankle
Biomechanics is a term to describe movement of the body. The ankle joint is responsible for 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 is also involved in two movements:
- Inversion: Turning the sole of the foot inward.
- Eversion: Turning the sole of the foot outward
The toes allow 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