Why do your knuckles pop? - Eleanor Nelsen

View full lesson: http://ed.ted.com/lessons/why-do-your-knuckles-pop-eleanor-nelsen Some people love the feeling of cracking their knuckles, while others cringe at the sound. But what causes that trademark pop? And is it dangerous? Eleanor Nelsen gives the facts behind joint popping. Lesson by Eleanor Nelsen, animation by Steve Belfer Creative.