A chiropractic adjustment is a type of manual therapy that seeks to realign joints as well as reduce muscle and nerve tension. Problems generally occur in the body when joints become fixated. This in turn alters the natural biomechanics of the body creating both muscular and joint compensation. After prolonged periods this results in pain, numbness, headaches and various other symptoms.
Although a number of chiropractic methods and techniques exist, the most common version of an adjustment involves a controlled but fast directional thrust into the desired joint. This helps to restore natural function and movement in the joint. On a more physiological level, this helps to release the Golgi tendon organs which are proprioceptive sensory receptor organs that senses changes in muscle tension. Also, the cracking that is heard is the release of synovial fluid which are gas bubbles which helps to create space and movement within the joint.