Dysphagia is the perception of difficulty in swallowing. Dysphagia caused by neuromuscular disorders may be accompanied by coughing and aspiration, particularly with liquid ingestion. Altered esophageal peristalsis is associated with the sensation that food has become stuck behind the sternum. Les dysfunction may be manifested as substernal pain. Pain is a common symptom of gi disorders. A heartburn type of pain is associated with esophageal reflux. Chest pain similar to anginal pain may result from esophageal distention and obstruction. Abdominal pain may be visceral (diffuse, poorly localized), somatic (sharp, well localized), or referred (at a distance from the source but in the same dermatome). Nausea and vomiting are manifestations of many gi and other disorders. Alterations in bowel motility or integrity are causative factors. Excess gas may result from altered motility or lack of digestive enzymes. Gas is generated by swallowed air and bacterial action on nutritional substrates.