Movement at the ankle (tibiotalar) joint is limited to dorsiflexion and plantar flexion. Plantar flexion is powered by the gastrocnemius, the posterior tibial muscle, and the toe flexors. Their tendons run behind the malleoli. The dorsiflexors include the anterior tibial muscle and the toe extensors. They lie prominently on the anterior surface, or dorsum, of the ankle, anterior to the malleoli.

Ligaments extend from each malleolus onto the foot.

■ Medially, the triangle-shaped deltoid ligament fans out from the inferior surface of the medial malleolus to the talus and proximal tarsal bones, protecting against stress from eversion (heel bows outward).

■ Laterally, the three ligaments are less substantial, with higher risk for injury: the anterior talofibular ligament, most at risk in injury from inversion (heel bows inward) injuries; the calcaneofibular ligament; and the posterior talofibular ligament (Fig. 1). The strong Achilles tendon attaches the gastrocnemius and soleus muscles to the posterior calcaneus. The plantar fascia inserts on the medial tubercle of the calcaneus.

FIGURE 1. Ankle, lateral view.

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