Ankle Joint Flashcards
Describe the articulations of the ankle joint
The ankle joint is formed by three bones; the tibia and fibula of the leg, and the talus of the foot:
The tibia and fibula are bound together by strong tibiofibular ligaments, producing a bracket shaped socket, which is covered in hyaline cartilage. This socket is known as a mortise.
The body of the talus fits snugly into the mortise formed by the bones of the leg. The articulating part of the talus is wedge shaped. It is wider anteriorly, and thinner posteriorly. During dorsiflexion, the anterior part of the bone is held in the mortise, and the joint is more stable (vice versa for plantarflexion).
Describe the ligaments of the ankle joint
There are two sets of ligaments, which originate from each malleolus. The medial ligament (or deltoid ligament) is attached to the medial malleolus. It consists of four separate ligaments, which fan out from the malleolus, attaching to the talus, calcaneus and navicular bones. The primary action of the medial ligament is to resist over-eversion of the foot.
The lateral ligament originates from the lateral malleolus. It resists over-inversion of the foot. It is comprised of three distinct and separate ligaments:
Anterior talofibular: Spans between the lateral malleolus and lateral aspect of the talus.
Posterior talofibular: Spans between the lateral malleolus and the posterior aspect of the talus.
Calcaneofibular: Spans between the lateral malleolus and the calcaneus.
What movements are permitted at the ankle joint?
The ankle joint is a hinge type joint, with movement only possible in one plane. Thus, plantarflexion and dorsiflexion are the only movements that occur at the ankle joint. Eversion and inversion are produced at the other joints of the foot, such as the subtalar joint.
Plantarflexion – Produced by the muscles in the posterior compartment of the leg; gastrocnemius, soleus, plantaris and posterior tibialis.
Dorsiflexion – Produced by the muscles in the anterior compartment of the leg; tibialis anterior, extensor hallucis longus and extensor digitorum longus.
