<unk> , also called reflective pain, is pain perceived at a location other than the site of the painful stimulus. An example is the case of angina pectoris brought on by a myocardial infarction (heart attack), where pain is often felt in the left side of neck, left shoulder, and back rather than in the thorax (chest), the site of the injury. The International Association for the Study of Pain has not officially defined the term; hence several authors have defined it differently. Radiating pain is slightly different from<unk> ; for example, the pain related to a myocardial infarction could either be<unk>  or radiating pain from the chest.<unk>  is when the pain is located away from or adjacent to the organ involved; for instance, when a person has pain only in their jaw or left arm, but not in the chest.<unk>  has been described since the late 1880s. Despite an increasing amount of literature on the subject, the biological mechanism of<unk>  is unknown, although there are several hypotheses.
Referred pain
Pain out of proportion
Pain tolerance
Referred itch
Pain wind-up
Pain and pleasure
Baricity
Pain