Escaping gases, movement and rough surfaces. Your joints can make a variety of sounds: popping, cracking, grinding, and snapping. The joints that "crack" are the knuckles, knees, ankles, back, and neck. There are different reasons why these joints "sound off". Escaping gases: Scientists explain that synovial fluid present in your joints acts as a lubricant. The fluid contains the gases oxygen, nitrogen, and carbon dioxide. When you pop or crack a joint, you stretch the joint capsule.
![What causes the noise when you crack a joint? (Everyday Mysteries: Fun Science Facts from the Library of Congress)](http://www.loc.gov/rr/scitech/mysteries/images/healthy-joint.gif)
Cracking or popping of joints. The physical mechanism causing a cracking sound. There are many ways people have learned to crack the joints of their fingers.
Joint clicking: A clicking sound that occurs during. most people can deliberately produce a clicking sound in various joints such as the neck, hips, fingers and.
- Cracking Knuckles: What is That Sound and. You yank on your fingers and. Physical therapists do it because they combine cracking joints through.
- If you've ever laced your fingers. producing the pop that. But assuming you haven't signed a multimillion dollar contract to constantly pop your knuckles.
- What causes the noise when you crack a joint? There are different reasons why these joints 'sound off'. Escaping. and popping / cracking joints.