Primarily somatic, arising from musculoskeletal (e.g. TMD pain or periodontal pain) or visceral structures (e.g. pulpal pain or pain from the salivary glands), and transmitted via an intact pain transmission and modulation system. Primarily neuropathic, which occurs as a result of abnormal or damaged pain pathways, e.g. a surgical or traumatic injury to a peripheral nerve. Primarily psychological, which is rare (See: psychogenic pain)