The Ankle & Foot

The ankle and foot are man's means of locomotion. This weight bearing mechanism also provides for balance, agility, and shock absorption for the body.

The anatomy of the foot and ankle includes 26 bones, ligaments, tendons, bursae, nerves, blood vessels, fat pads, and synovial capsular joints.

Kinesiology of the foot includes Proprioception, kinesthesia, the arches, shock absorption, weight distribution, 3 planes of motion and multi axial accessory motions.

Each joint is responsible for either a primary or secondary motion.

Ankle joint or mortis joint

Bones = talus, tibia, fibula

Movements = plantar flexion 40 - 50 degrees, pointing the toe down, as in "planting or plowing"

Dorsi flexion 15 - 20 degrees [ pulling the foot upward towards the leg ]

Accessory motion = is due to the increased width of the talus in its anterior portion. When the foot is in dorsi flexion, the talus is wedged between the tibia and fibula which spreads these two bones. The fibula will also move proximally and medially rotate. When the foot is in plantar flexion, the smaller part of the talus articulates with the tib-fib mechanism and the fibula moves distally and laterally rotates. This allows for less stability and thus the majority of injuries that are seen occur when the foot is plantar flexed.

Ligaments

Inferior Tibio - fibular ligament ,controls accessory spreading of the tibia and fibula

Lateral collateral group = consists of the Anterior Talofibular, the Posterior Talofibular, and the Calcaneal Fibular portions. The bifurcated ligament along with the talonavicular ligament and the calcaneonavicular ligament support the mid foot. These ligaments are often injured in conjunction with inversion, plantar flexion movements.

Medial collateral ligament is primarily considered the deltoid ligament. Deep portions of the medial group consist of the talotibial in its anterior and posterior portions.

Superior extensor retinaculum or transverse cruciate ligament which crosses the top of the ankle and foot.

The Foot Joints

Subtalar joint

The bones involved with the sub talar joint are the top of the Calcaneus and the bottom of the talus. These two bones are fairly congruent which affords joint stability.

Movement

Pronation and supination

Pronation is also referred to as eversion.

Supination is also referred to as inversion.

The ligament involved is the interosseous talocalcaneous. The surrounding muscles and their attachments help with the stability.

Transverse tarus joints

Bones involved are the articulations between the talus and Navicular and between the Calcaneus and the cuboid.

Movement is considered to be only 3 degrees of accessory motion in pronation and supination

The ligaments are multi and small. The spring ligament or plantar calcaneal-navicular ligament supports the medial arch along with the flexor hallucis longus and brevis.

The muscles are many but in addition to the flexor hallucis supporting the medial arch the tibialis posterior supports the transverse arch.

Intertarsal joints

Bones involved are the tarsals, = cuboid, navicular, and the 1-2- 3 cuneiforms

Movements include both inversion and eversion and an accessory gliding motion between the lateral surfaces of the tarsals. This gliding allows for some shock absorption.

The ligaments are multiple small ligs. with joint capsules surrounding the joints.

The muscles are also numerous however the peroneus longus tendon supports the transverse arch with along the posterior tibialis.

Tarsometatarsal joints

Bones involved are the 3 cuneiforms and the cuboid articulation with the metatarsals.

Movements include accessory motions in dorsi and plantar flexion and with shock absorption.

The ligaments are mainly capsular and retinacular. The muscles and tendons in this area provide a lever system for the movements of the toes.

Metatarsal phalangeal joints

Bones involved are the metatarsals and the phalanges.

Movements include flexion and extension as well as limited ab - adduction. The ligaments and muscles provide a pulley system within the tendinous sheaths. The mp joints also provide the main propulsion force in the push off.

Interphalangeal joints

Bones involved are the digits of the phalangeals.

Movements include flexion and extension. The ligaments and capsules are very similar to the fingers and the knee.

Arches

Transverse arch

The transverse arch runs the length of the foot. It begins at the navicular and cuboid and is dependent on the posterior tibialis tendon. At the level of the cuneiforms and cuboid the arch is supported by the peroneus longus tendon. The arch ends at the metatarsal heads where it is relatively flat. The transverse arch is supported at the metatarsal heads by the by the adductor hallucis muscle. The plantar fascia may affect the arch depending upon its level of flexibility.

Medial arch

The medial arch runs along the medial aspect of the foot and includes the calcaneus, talus, navicular, medial cuneiform, and the 1st metatarsal. It is supported by the flexor hallucis longus, abductor hallucis longus, posterior tibialis, peroneus longus, and the flexor digitorum longus. The supporting ligament is the spring ligament or the plantar calcaneal - navicular ligament. This is the highest arch in the foot.

Lateral arch

The lateral arch is relatively flat and helps with weight distribution during the gait. The bones involved are the calcaneus, cuboid, and the 5th metatarsal. The peroneus longus and brevis, and the abductor digiti minimi are the dynamic support for this arch.

The plantar vault

This is the culmination of all three arches working together for shock absorption and gait activities.