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Merck Manual

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Throat and Esophagus


Atenodoro R. Ruiz, Jr.

, MD, The Medical City, Pasig City, Philippines

Last full review/revision Oct 2019| Content last modified Oct 2019
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The throat (pharynx—see also Throat) lies behind and below the mouth. When food and fluids leave the mouth, they pass through the throat. Swallowing of food and fluids begins voluntarily and continues automatically. A small muscular flap (epiglottis) closes to prevent food and fluids from going down the windpipe (trachea) toward the lungs. The back portion of the roof of the mouth (soft palate) lifts to prevent food and fluids from going up the nose. The uvula, a small flap attached to the soft palate, helps prevent fluids from passing upward into the nasal cavity.

The Digestive System

The Digestive System

The esophagus is a thin-walled, muscular channel lined with mucous membranes that connects the throat with the stomach. Food and fluids are propelled through the esophagus not only by gravity but also by waves of rhythmic muscular contractions called peristalsis. At either end of the esophagus are ring-shaped muscles (the upper and lower esophageal sphincters), which open and close. The esophageal sphincters normally prevent the contents of the stomach from flowing back into the esophagus or throat.

How the Esophagus Works

As a person swallows, food moves from the mouth to the throat, also called the pharynx (1). The upper esophageal sphincter opens (2) so that food can enter the esophagus, where waves of muscular contractions, called peristalsis, propel the food downward (3). The food then passes through the diaphragm (4) and lower esophageal sphincter (5) and moves into the stomach.

How the Esophagus Works
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