Ankle Joint: The Ankle Joint, also known as the Talocrural Articulation, is a synovial type of hinge joint connecting the distal ends of the tibia and fibula of the lower limb with the proximal end of the talus bone.
Functionally, a hinge type joint, permitting dorsiflexion and plantarflexion of the foot.
Articulating Surfaces of Ankle Joint
The ankle joint is composed of three bones; the tibia and fibula of the lower limb, including the talus of the foot:
- The tibia and fibula are connected together by powerful tibiofibular ligaments, providing a bracket shaped socket, that is covered in hyaline cartilage. This socket is distinguished as a mortise.
- The body of the talus bone hangs snugly into the mortise formed by the bones of the distal end of tibia and fibula. The articulating part of the talus is wedge-shaped. It is broader anteriorly, and thinner posteriorly. While dorsiflexion, the anterior part of the bone is held in the mortise, and the joint is stronger stable (vice versa for plantarflexion).
Ligaments of Ankle Joint
There are two sets of ligaments, that originate from individual malleolus. The medial ligament (known as deltoid ligament) is connected to the medial malleolus. It consists of four separate ligaments, that fan out from the malleolus, connecting to the talus, calcaneus, and navicular bones.
The principal action of the medial ligament is to resist over-eversion of the foot.
The lateral ligament arises from the lateral malleolus. It counters over-inversion of the foot. It is composed of three distinct and separate ligaments:
- Anterior talofibular ligaments: Spans within the lateral malleolus and lateral aspect of the talus.
- Posterior talofibular ligaments: Spans among the lateral malleolus and the posterior aspect of the talus.
- Calcaneofibular ligaments: Spans within the lateral malleolus and the calcaneus.
Movements and Muscles Involved in Ankle Joint
The ankle joint is a synovial type of joint, with movement only possible in one plane. Therefore, plantarflexion and dorsiflexion are the only movements that happen at the ankle joint. Inversion and Eversion are allowed at the other joints of the foot, such as the subtalar joint.
- Dorsiflexion – Produced by the in the anterior compartment of the leg muscles; tibialis anterior, extensor hallucis longus and extensor digitorum longus.
- Plantarflexion – Offered by the muscles in the posterior compartment of the leg; gastrocnemius, soleus, plantaris and posterior tibialis.
Neurovascular Supply of Ankle Joint
The arterial supply is received from the malleolar branches of the anterior tibial, posterior tibial and fibular arteries. Innervation is rendered by –
- Common Peroneal Nerve
- Tibial Nerve