After the Civil War , with the protection of the Thirteenth , Fourteenth , and Fifteenth Amendments to the Constitution and the Civil Rights Act of 1866 , African Americans enjoyed a period when they were allowed to vote , actively participate in the political process , acquire the land of former owners , seek their own employment , and use public ...
In the knee, for example, cracking or popping may occur if the patella (knee cap) is slightly out of alignment, and rubs on the adjacent tissues. Other causes of joint noise are the snapping of tendons or scar tissue over a prominence or something referred to as cavitation. Cavitation frequently occurs in synovial joints when a small vacuum forms in the synovial fluid and a rapid release produces a sharp popping or cracking sound.
Harmless pops. The most common noises are what he calls benign pops or high-pitched snaps. These are thought to occur when the fluid-filled sac within joints gets stretched by a sudden change in joint position. The resulting pressure and volume change, pulls some dissolved gases out of solution [from the joint fluid] and the gases make bubbles that are unstable and pop.