A sprain of the lateral ankle typically involves which ligament?

The correct answer is the anterior talo-fibular ligament. This ligament is a critical component of the lateral ankle structure and is the most commonly injured ligament in cases of ankle sprains. A sprain generally occurs from an inversion injury, where the foot turns inward, putting stress on the ligaments on the outside of the ankle.

The anterior talo-fibular ligament connects the talus bone to the fibula and plays a vital role in stabilizing the ankle joint during movement. When this ligament is sprained, it can lead to pain, swelling, and instability in the ankle.

In contrast, the other ligaments listed serve different functions or are located in other regions of the ankle. For example, the spring ligament is important for maintaining the arch of the foot, the inferior talo-calcaneal ligament is involved in subtalar joint stability, and the deltoid ligament, which is located on the medial side of the ankle, primarily provides stability against eversion forces. Therefore, the emphasis on the anterior talo-fibular ligament highlights its direct association with lateral ankle sprains.