The main focus of chiropractic is the relationship between the skeleton (particularly the spine) and the nervous system. Diagnosis is primarily based on physical examination and x-ray. Misalignments of the vertebrae caused by poor posture or trauma can lead to decreased function, pain and illness. The chiropractor uses his or her hands to manipulate the spine and bring it back into alignment. Chiropractic is commonly used to treat back pain, headaches, and injuries, and is also used as a preventive therapy.