Temporomandibular joints (TMJ) are the muscles and joints used to open and close your mouth. TMJ disorders can be caused by injury to the face and jaw regions, bite problems, clenching your jaw, grinding teeth, whiplash, and even poor posture resulting in damage to the joints or misalignment. Facial, tooth and ear aches as well as “clicking” in the jaw, headaches, back, neck and shoulder pain can occur.