What is the primary action of the medial ligament of the ankle?

The primary action of the medial ligament of the ankle, also known as the deltoid ligament, is to resist over-eversion of the foot. This ligament is a strong, triangular structure that broadens as it extends from the medial malleolus of the tibia to several tarsal bones, including the navicular, the talus, and the calcaneus.

When the foot experiences forces that try to evert it (turn it outward), the deltoid ligament provides stability and prevents excessive movement that could lead to injury, such as a sprain. The structure of the ligament and its attachment points are specifically designed to limit this everted position, which is crucial for maintaining the integrity of the medial ankle region during activities that involve uneven surfaces or sudden directional changes.

Understanding the function of the medial ligament helps in assessing injuries and developing rehabilitation strategies for conditions associated with ankle instability, particularly those that result from excessive eversion.