While there are many causes of headaches, the most common cause is“tension” or stress overload leading to dysfunction. Nerves from the neck region go to the muscles of the neck that attach to the base of the skull. When you experience “subluxation interference”, the resulting “pinching” of the nerve tells the corresponding muscles to tighten which restricts blood flow which you then experience as a tension headache. Locating and removing the nerve pressure oftentimes allows the muscle to relax and your headache symptom to no longer be present.