The epigastrium is one of the nine anatomical regions of the abdomen, along with the right and left hypochondria, right and left lateral regions (or flanks), right and left inguinal regions (or fossae), and the umbilical and pubic regions.
During breathing the diaphragm contracts and flattens, displacing the viscera and producing an outward movement of the upper abdominal wall (epigastric region). It is a convergence of the diaphragm and the abdominals, so that "when both sets of muscles (diaphragm and abdominals) tense, the epigastrium pushes forward". Therefore, the epigastric region is not a muscle nor is it an organ, but it is a zone of activity where the actions of the rectus abdominus and the diaphragm produce an outward bulging of the upper abdominal wall. It is also the spot where the Heimlich Maneuver is able to produce a rapid and forceful exhalation of breath.