|Curtis, Helena, & Sue N. Barnes. "The Pharynx and Esophagus: Swallowing. " Biology. 5th ed. New York: Worth, 1989: 718.||"From the mouth, food is propelled backward toward the esophagus, a muscular tube about 25 centimeters long in adult humans"||25 cm|
|Liebow, Charles. "Esophagus." World Book Online Americas Edition.30 May 2001.||"The human esophagus is about 10 inches (25 centimeters) long. The esophagus of fish is short, while that of giraffes is extremely long."||25 cm|
|Pope II, Charles E. "Normal Anatomy and Developmental Anomalies." Gastrointestinal Disease: Pathophysiology/Diagnosis/Management. By Marvin H. Sleisenger and John S. Fordtran. Philadelphia: Saunders, 1993: 311.||"Its length, as measured in the cadaver, ranges from 25 to 30 cm in the adult."||25–30 cm|
|Blakiston. "Esophagus." Blakiston's Gould Medical Dictionary. 4th ed. New York: McGraw-Hill, 1979.||"Esophagus–The musculomembranous canal, about nine inches in length, extending from the pharynx to the stomach; the gullet."||23 cm|
|Stedman, Thomas Lathrop. "Esophagus." Stedman's Medical Dictionary. 27th ed. Baltimore: Lippincott Williams & Wilkins, 2000.||"It is about 25 cm long and consists of three parts: the cervical part, from the cricoid cartilage to the thoracic inlet; the thoracic part, from the thoracic inlet to the diaphragm; and the abdominal part, below the diaphragm to the cardiac opening of the stomach."||25 cm|
Digestion involves the breakdown of ingested food and the absorption of the resulting molecules into the body. These molecules provide energy and raw materials for essential synthetic processes. In humans, the digestive system consists of mouth, pharynx, esophagus, stomach, small intestine and large intestine.
Once food enters the mouth, it is chewed until pushed into the pharynx, the intersection leading to both the esophagus and trachea (windpipe). As food descends down the digestive tract, the cartilaginous epiglottis tips down in order to prevent food from entering the trachea. The food mass passes into the esophagus (also called the gullet) a mucous coated tube extending from the pharynx to the stomach. In humans, swallowing begins as a voluntary action, because the upper part of the esophagus consists of striated muscle. However, the lower part of the esophagus is smooth muscle. Food continues moving involuntarily down the flexible esophagus to the stomach, squeezed along by rhythmic waves of muscular contraction known as peristalsis. Peristalsis is such an efficient process that it even enables humans to swallow water while standing on our heads. Located at the junction of the esophagus and the stomach is the lower esophageal sphincter, a muscular ring that prevents food from reentering the esophagus.
The human esophagus consists of three parts, which total to a length of about 25 cm. Not only does the length of the esophagus vary among humans, but also among different animals. For example, a fish would possess a shorter esophagus than a giraffe.
Jennifer Tran -- 2001