There are several ligaments around your ankle. The two main ones are the anterior talofibular ligament and the calcaneofibular ligament. Both connect to your fibula. That's the thin bone outside your shinbone. It's also the bone you feel on the outside of your ankle.
The calcaneofibular ligament connects the fibula to your heel bone.
The anterior talofibular ligament connects the talus (the bone between your heel and shinbone) to the fibula on the outside of the ankle.