The fibula is the thinner of the two bones in the lower leg. It sits parallel to the tibia, or shin bone, and despite its size, plays many important roles that facilitate leg movement. Though the tibia and the fibula are about the same length, the fibula is significantly thinner. This shows the difference between the bones’ functions. While the tibia bears the body’s weight and absorbs stress, the fibula acts as a supporting structure for the tibia.


1. Proximal End

The upper end of the fibula sits just behind the head of the tibia, underneath the knee. Anatomically, this is the proximal end, though some physicians call it the head. Proximal is an anatomical term that describes an object that is closer to the center of the body. The head of the fibula expands outward in all directions and has an irregular quadrate form; in other words, it is square-like but has irregular sides. At the top of the head, a thick, pointed shape emerges. This shape is the apex or styloid process of the fibula. Immediately under the head, the fibula constricts to form the thin neck of the bone.

proximal head fibula PALMIHELP / Getty Images

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