Esophagus

The esophagus is the long, flexible tube which leads from the pharynx in the upper throat to the stomach. The average esophagus is about ten inches long, and its walls are made of muscle fibers which contract in waves (called peristalsis) to push the bolus (globule) of chewed food and saliva down to the stomach.

The common ailment of heartburn occurs when stomach acid washes back up into the esophagus.  Since the esophagus has no protective mucosal layer, as does the stomach, this acid causes pain which generates just behind the sternum (breastbone) and seems to come from the heart, hence the term "heartburn" is often used.

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