Eversion in the medical terms is referred to the state of being turned inside out or rotated outward. The inversion and eversion refers to the movements that tilt the sole of the foot away from (eversion) or towards (inversion) the midline of the body. Eversion is the movement of the sole of the foot away from the median plane. Inversion is the movement of the sole towards the median plane. Kids usually experiment with movements, the one movement which is quiet difficult to perform is eversion which is literally means turning the inside out. In anatomical terms everting the foot means lifting up the lateral that is edge of the foot. When you do so that is you will be standing on the inside of the foot. The opposite of the eversion is inversion which is when you stand on the outside edge of the foot. The eversion is the movement of the ankle in the frontal plane, which means the movements run parallel to the front and back of the body. The eversion is basically the joint movement section which is about the types of movements between the joints and the bones in our body.

Anatomy of foot

The ankle and the foot form a complex system which generally consist of 33 joints, 28 bones and controlled by 21 intrinsic muscles. The foot is usually subdivided into the mid foot, rear foor and forefoot. It functions as a rigid structure for weight bearing; it also has a function to provide flexible structure to conform the uneven terrain. The various functions of foot and ankle include:

Supporting body mass

Providing balance to the body\

It involves in shock absorption

Transferring the ground reaction forces

Compensating for the proximal improper alignment

The substituting hand functions in the individuals with the upper extremity paralysis and amputation.

Talocrural Joint

The joint is formed between the distal tbia-fibula and the talus, and is commonly known as the ankle joint. The inferior and distal aspect of the tibia-known as the plafond- is connected to the fibula via tibiofibular ligaments forming a strong  mortise which articulates with the distally talar dome. It is basically the hinge joint and allows for plantarflexion and dorsiflexion movements in the sagittal plan.

Subtalar Joint

This joint is also known as the talocalcalneal joint and is basically formed between the calcaneus and talus. The talus has three facets (posterior, middle and anterior). This can articulate inferiorly with the calneous.

Midtarsal Joint

The midtarsal is also known as the tranaverse joints or also known as the Chopart’s joint. The shape of the midtarsal is S shaped joint when it is viewed from the above and it is comprised of two joints which is known as the talonavicular joint and caalcaneocuboid joint.

Talonavicular joint- It is formed between the concavity and anterior talar head on the navicular. It basically does not have its own capsule, but it shares one with the two anterior talocalcaneal articulations.  

Calcaneocuboid Joint- It is formed between the posterior cuboid and the anterior facet of the calcaneous. The articulating surface represents a concave and convex surface. The joint which is convex is vertically in nature and the concave surface is transversely arranged in the foot.

Tarsometatarsal Joint Complex- It is also called as Lisfranc’s joint. Including the three cuneiform bones and the cuboid articulate the distal tarsal rows with the base of each metatarsal to form the Tarsometatarsal joint complex. It is structured in “S” shaped joint and is divided mainly into three distinct columns.

An ankle sprain is a tear in the ligament of the ankle. These ligaments hold the parts of the ankle in one place or connect it to the other bones in the foot or leg. The types of ankle sprains are eversion ankle sprains and inversion ankle sprain. The eversion ankle sprain occurs when the ankle rolls outward and tears the deltoid ligaments. The inversion ankle sprain occurs when a person twists the foot upward and the ankle rolls.

Eversions use muscles on the lateral sides of the leg, including the peroneus longus and brevis. The muscles of eversion all have 'e' as the second letter: peroneus longus, peroneus brevis and peroneus tertius. These muscles run on the lateral side of your leg. When these muscles shorten they pull up on the lateral bones of your foot (the 4th and 5th metatarsals) and evert your foot.

The types of eversion in the foot are:

Joints taking part

The subtalar joint is the joint in the foot which is the meeting point of the talus and the calcaneus.

The talocalcaneonavicular joint is basically a ball and socket joint: the rounded head of the talus is being received into the concavity which is formed by the posterior surface of the navicular, the anterior articular surface of the calcaneus, and the upper surface of the plantar calcaneonavicular ligament.

Transverse tarsal joint: The transverse tarsal joint is actually a combination of the following two joints: Talocalcaneonavicular joint: This synovial joint is formed between the talus and the calcaneus and the navicular bones.

Axis of the movement

The movement of inversion and eversion generally take place around an oblique axis which runs forward, upward and medially going from the rear of calcaneumvia the sinus tarsi to appear at the superomedial aspect of the neck of talus.

Range of the movement

The range of the movement of inversion is quite far more than that of the eversion that is inversion is 30 degree and eversion is 20 degree. The range of these movements is appreciably raised in plantar flexion of the foot because in this position, the narrow posterior part of the trochlear surface of talus takes up thhe tibiofibular socket (mortise) which allows some level of side to side movements of the talus.

Functional Importance

The movements of inversion and eversion are essential for walking on uneven and sloping grounds. They significantly help the foot in correcting it to such reasons. When feet are supporting the body weight, these movements take place in a modified create termed supination and pronation.

Tarsometatarsal Joints

All these are plane type of synovial joints. They may be joined by dorsal, plantar, and interosseous tarsometatarsal ligaments. They’re 5 in number. The very first joints possesses another cavity, the 2nd and third together have 1 cavity. These joints allow only small gliding movements.

Metatarsophalangeal Joints

These are the ellipsoidal type of the synovial joints in the foot. They’re joined with the capsular, collateral, plantar, and deep transverse metatarsal ligaments. 2 collateral ligaments reinforce the sides of every joint. These joints allow the small gliding movements. The deep transverse ligaments (4 in number) attach the plantar ligaments of adjacent metatarsophalangeal joints.

Movements

These joints allow dorsiflexion, plantar flexion, adduction, and abduction.

• The range of dorsiflexion is more (50-60 °) than that of plantar flexion (30-40 °).
• The axis of adduction and abduction of the toes goes through the least mobile 2nd metatarsal bone. (cf. the axis of adduction and abduction of fingers goes through the third metacarpal bone.)

The muscles which are responsible for eversion and inversion of the foot are:

The tibialis posterior and anterior mucles invert the foot. The fibularis and the extensor digitorum longus muscles evert the foot.