What is it? The esophagus is a muscular tube that carries food from the pharynx to the stomach. It’s hollow - the interior is called the lumen. The interior layers of the tube are mucosal (squamous epithelium) and submucosal connective tissue layers. The outer layers of the tube are layers of muscle fibers and fibrous tissue.
Gross fact: In human adults, the esophagus is 25-30 cm in length on average.
How does it function? The esophagus moves swallowed contents via peristalsis. What can enter the esophagus is controlled by a sphincter at either end.
The upper esophageal sphincter is a muscular ring where the trachea and esophagus divide off from the pharynx.
Structures of the throat
What is it? The throat is the front and interior of the neck. It contains a mucosa-lined tube that begins at the laryngopharynx and then divides into the esophagus (to the stomach) and trachea (to th…
The upper esophageal sphincter relaxes during the swallowing reflex and contracts during rest to prevent air from diverting into the stomach.
The lower esophageal sphincter connects the esophagus to the stomach. It also relaxes during the swallowing reflex and contracts at rest. It prevents the backflow of stomach acid and digested food into the esophagus.
Another gross fact: With aging, the sphincters lose strength, increasing the risk of acid reflux.
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