Tibia and fibula
The lower leg has two bones. The tibia, the shin bone, carries the body's weight from the knee to the ankle. Its front edge lies just under the skin, which is why a knock on the shin hurts so much. The slender fibula on the outer side carries little weight, but many muscles attach to it.
The bones of the right leg from the front, the tibia and the fibula, Gray's Anatomy, 1918, figure 258Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray258.png)
The two are bound along their length by the interosseous membrane and at the bottom by strong ligaments. Their lower ends, the knobs on either side of the ankle, grip the talus of the foot like a fork. The ankle joint hinges here, tilting the foot up and down.
The ankle ligaments hold the talus in this fork. Rolling the foot onto its outer edge strains the outer ones, and a sprained ankle usually means a torn anterior talofibular ligament, the one at the front.
The left ankle from the outer side, with the anterior and posterior talofibular ligaments and the calcaneofibular ligament, Gray's Anatomy, 1918, figure 356Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray356.png)
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), chapters on the leg and on the ankle and foot.
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