The ankle consists of three bones attached by muscles, tendons, and ligaments that connect the foot to the leg.
In the lower leg are two bones called the tibia (shin bone) and the fibula. These bones articulate (connect) to the Talus or ankle bone 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.
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 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 tissue that connects bones to other bones and help hold tendons in place providing stability to the joints. The plantar fascia is the longest ligament in the foot, originating at the calcaneus, heel bone, and continuing along the bottom surface of the foot to the forefoot. It is responsible for the arches 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 talo-fibular ligament and the calcaneo-fibular ligament.
- Muscles: Muscles are fibrous tissue capable of contracting to cause body movement. There are 20 muscles in the foot and these 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 without being properly warmed up.
- 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 Ankle
Biomechanics is a term to describe movement of the body. The ankle joint by itself 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.