What Happens When You Crack Your Back?

What Happens When You Crack Your Back? Many people crack their back, knuckles, and other joints, but what is actually happening when you crack your back, and what causes the popping noise? Cracking your back stretches squishy capsules on the outer edges of the vertebrae around joints called facet joints. Stretching these capsules allows the synovial fluid inside them to have more space to move around, releasing pressure on your back joints and muscles and moving your facet joints. What is the top reason for a cracking back?