Ligaments are known for the ability to limit motion. They receive a lot of attention when the forces imposed on a ligament exceeds its ability to resist, resulting in a tear / rupture. Ligaments can take the form of a separate structure or a thickened reinforced section of a joint capsule. In either form, the ligaments have sensors that respond to tension. The presence of these sensors insures that the role of ligaments goes well beyond functioning as a passive restraint of motion.