Bones of the Ankle

Bone is a special type of hard connective tissue. Bone tissue is made up of different types of bone cells. The word ankle or ancle is common in most of the German languages, the origin of this word is from the Latin word “Angulus” or in Greek “αγκυλος”. In an adult human, there are about 206 bones. There are five types of bones in the human body that include: long bones, short bones, flat bones, sesamoid bones, irregular bones. Short bones are cube-shaped bones that consist of ankle and wrist bones.

The region where the foot and leg meet is called the talocrural region or ankle. From the narrow west point of the lower leg that extends to the downwards and it includes the foot that is closer to the body, to the heel and upper surface of the foot. Let us learn more about ankle bone anatomy..

Ankle Joint Anatomy

The only mortise and tenon joint in the body is the ankle joint bones. The bony architecture of the ankle consists of three bones, they are:

1. Tibia

2. Fibula

3. Talus

The body of the talus fits comfortably or in a well-protected manner to the mortise. The articulating pattern found on the talus is in a wedge shape which is broader in the anterior position and narrower in the posterior position. 

Dorsiflexion is the anterior part of the talus that is held in the mortise where the joint is found to be more stable. Plantarflexion is the posterior part of the talus that is connected to the mortise and the joint is less stable than the dorsiflexion. 

Ankle Joint Anatomy - Ligaments:

The ankle joint is strongly bound by the deltoid ligaments and the lateral ligaments that are classified into three types:

1. Anterior talofibular ligament

2. Posterior talofibular ligament

3. Calcaneofibular ligament

The deltoid ligament is attached at the medial malleolus of the tibia and supports the medial side of the joint. It is connected to the talar shelf in the four places such as the calcaneus, calcaneonavicular ligament, the navicular tuberosity, and the medial surface of the talus.

The anterior talofibular ligaments and the posterior talofibular ligaments support the lateral side of the joint from the lateral side of the malleolus present on the fibula to the ventral and dorsal end of the talus.

The calcaneofibular ligament is attached to the lateral surface of the calcaneus and the lateral malleolus.

Ankle Joint Anatomy - Tendons, and their Nerves

There are numerous tendons that pass through the ankle region. The connective tissue in the form of bands called retinacula. By the process called bowstringing retinacula allow the tendons to exert force in between the angle of the leg and foot without lifting away from the angle. Near the lower ends of the tibia and fibula, the superior extensor retinaculum of the foot extends in between their anterior surface. The inferior extensor retinaculum is in a Y shape. 

Mechanoreceptors that are present in the ankle send proprioceptive sensory input to the CNS(Central nervous system). The main type of mechanoreceptors that are responsible for the proprioceptive sensory input is muscle spindles.

Clinical Significance

Among all the joints the major fracture occurs to the ankle. The defect in the ankle bone structure can lead to several clinical significances, that include:

1. Traumatic Injury: 

During weight-bearing the outer surface of the foot is twisted, the anterior talofibular porion is subjected to tearing that resists the inward rotation of the talocrural joint.

2. Ankle Ring: 

In the coronal plane the ankle joints and the ligaments can be visualized in the form of a ring. Where the upper part is formed by tibia and fibula articular surfaces, and the lower part is formed by the subtalar joint. The sides are formed by the medial and lateral ligaments. So when damage occurs to the ring it breaks in two places.

3. Ankle Sprain: 

The partial or complete tear of the ligament is referred to as an ankle sprain. It occurs due to excessive inversion of the plantarflexed and weight-bearing foot. The damage that occurred for the anterior talofibular ligament is irreversible damage. 

4. Pott’s Fracture(Dislocation): 

The term used to describe a bimalleolar or trimalleolar fracture is called pott’s fracture. 

This injury occurs due to forced eversion of the foot, which includes:

• Pulls on the medial ligaments that damage the medial malleolus.

• If the talus is moved that breaks the lateral malleolus.

• When the tibia is forced anteriorly the distal and posterior part is sheared off.

5. Abnormalities: 

The downward deflection of the ankle or inward rotation of the foot leads to walking like a horse it is termed as Equinus. 

Conclusion

The bones play an important role in the musculoskeletal system. The bones in your ankle and the ends of the two lower leg bones combined to form an ankle joint. The ligaments help in the connection of bones from one to another which helps to support and stabilize. The ankle consists of three bones: tibia, fibula, and talus. The ankle bone name is called the talus that connects the leg to the foot. These bones help to move the ankle side-by-side, up and down without any pain. It also helps humans to perform various functions.