Vertebral subluxation is a chiropractic term that is use by some chiropractors to describe a myriad of signs and symptoms (syndrome) thought to occur as a result of a misaligned or dysfunctional spinal segment. The chiropractic subluxation complex is a functional biomechanical spinal lesion with purported altered neurological function that can result in neuromusculoskeletal and visceral disorders. This is in contrast to medical definition of spinal subluxation which is a gross misalignment of a joint that can be objectively measured. The chiropractic vertebral subluxation complex has been a source of controversy and confusion since its inception in 1895 with critics both inside and outside the profession due to its metaphysical origins and claims of far reaching effects. Officially, the WHO definition of vertebral subluxation is: