It is usually the knuckles, knees, ankles, back and joints of neck muscles that make the popping sound. It is caused by a small bubble that builds up in the fluid of the fingers. When these joints are pulled apart, a tiny cavity is formed which gets filled with gas. This gas bubble collapses and makes the popping sound. Since it takes some time before the gas can be re-dissolved in the slippery fluids, it is difficult to ‘re-crack’ the joints immediately.
Why do cracking fingers make sound?
