The fibula (Figure 3.30) is slender and is located lateral to the tibia. The proximal end is widened into the head. The head of the fibula articulates with thetibia, just inferior to the lateral condyle of the tibia. Along the shaft, a thin ridge, the interosseous crest,marks the surface that gives attachment to the strong connective tissue interosseous membrane. The in-terosseous membrane bridges the gap between the tibia and the fibula along the two shafts, stabilizing the bones and increasing the anterior and posterior surface area for attachment of muscles. The lower end of the fibula widens to form a prominence called the lateral malleolus. The bony projection on the lateral aspect of the ankle is the lateral malleolus that articulates with the talus bone. Although the upper end of the fibula does not participate in the knee joint, the lower end is an important component of the ankle joint.