Anatomy Guide › Lower limb
Fibula
The fibula is the tibia's thin companion, running down the outside of the lower leg like a brace strut. Its name comes from the Latin for a clasp or brooch pin — the fibula and tibia together reminded ancient anatomists of a pin fastened alongside a bar. Unlike the tibia, it bears little of the body's weight; estimates put its share at only around a tenth. Its upper end does not even reach the knee joint.
What the fibula lacks in load-bearing it repays at the ankle. Its lower end forms the lateral malleolus — the prominent knob on the outside of your ankle — which cups the talus and keeps the foot from rolling outward. This is the bone most involved in common ankle fractures: land awkwardly from a jump or catch an edge on a curb, and the twisting force frequently snaps the fibula just above the joint. The ligaments binding fibula to tibia (the syndesmosis) are what a 'high ankle sprain' injures.
The fibula's greatest fame, though, may be surgical. Because it is long, straight, has its own reliable blood vessel, and is largely expendable, it is the reconstructive surgeon's favorite donor bone. Segments of fibula — sometimes with skin attached — are transplanted to rebuild jaws after cancer surgery and to bridge large bone defects elsewhere. People walk, run, and jump on legs missing most of their fibula.
In Anamo, the fibula defines the outer lane of the lower leg, paired with the tibia the way the ulna pairs with the radius above. The long toe muscles and the calf's outer compartment hug it — useful adjacency when ankle-region rounds heat up.
- Bears only about a tenth of the leg's load
- Forms the outer ankle knob that stabilizes the joint
- The bone most often broken in common ankle fractures
- The favorite donor bone for reconstructive surgery, including jaw rebuilds
Think you could find the fibula on a 3D model? Play Anamo and test yourself — every guess is color-coded by how close it lands to the mystery structure.