Crepitation is the noise heard during joint movement. Such as clicking cracking grinding or popping. you may have experienced this in your joints such as knuckles knees or neck. Here are some possible causes of the sounds. Articular pressure changes. Synovial joints have a joint capsule filled with synovial fluid the volume and pressure within these joints may change with certain movements as result pressure changes within the joint can cause tiny bubbles which can collapse again which play a part in making a cracking noise such as when you purposely crack your knuckles or neck.
Bone on bone grinding: As joint deteriorate during arthritis the protective cartilage wears down and adjacent bones may rub against each other. A similar process can occur when discs degenerate. When cushioning between bones wears away the bone on bone sounds are typically repeatable with each movement.
Ligament or tendon snapping over bone: In some cases ligaments or tendons make snapping sounds when they move around the bone or over or over each other. This can occur because our muscles or soft tissues are tight or because they become less elastic with age.
Neck crepitus is rarely serious and doesn’t represent anything serious however if it is painful you should consult your health practitioner.