Chiropractic as a profession began over 100 years ago, and is the science and art of adjusting or manually manipulating the spinal column and other articulations of the body to diagnose, treat and prevent disease and abnormalities of the human body caused by interference with the nervous system. Chiropractic Physicians examine patients to determine the nature and extent of the disorder, often employing instruments and equipment such as radiography, electrocardiography, and electromyography. As a primary care physician, Chiropractors are trained in various diagnostic and therapeutic techniques, and may use supplementary measures, such as exercise, electrical stimulation, rest, water, light, heat, nutritional and diet therapy, and minor surgery. Chiropractic also trains in sub-specialties including sports medicine, orthopedics, radiology, neurology, and clinical nutrition, and in some states proctology, gynecology & obstetrics, and minor surgery.