Referred pain , 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. Referred pain has been described
since the late 1880s. Despite an increasing amount of literature on the
subject, the biological mechanism of referred pain is unknown, although there
are several hypotheses.