Which statement accurately describes the esophageal phase?

• A. It begins with the bolus entering the mouth and ends with the bolus passing UES
• B. It is entirely voluntary
• C. Food moves through the esophagus via relaxation of the UES and LES plus peristaltic contraction
• D. It lasts less than 2 seconds

Answer: (C)

The esophageal phase relies on coordinated, largely reflexive movement that pushes the bolus downward while gates at the top and bottom of the esophagus open and close. Once the pharyngeal stage delivers the bolus into the esophagus, the upper esophageal sphincter relaxes to admit the bolus, and then the esophagus undergoes peristaltic contractions to propel it downward. As the bolus nears the stomach, the lower esophageal sphincter relaxes to allow entry into the stomach, and then closes to prevent reflux. This combination—release at both sphincters and sequential muscular contractions—drives the bolus from the esophagus into the stomach.

The other statements don’t fit: the esophageal phase isn’t described by starting in the mouth and ending at the UES (that’s the oral phase); it isn’t entirely voluntary (the esophageal movement is largely automatic); and it typically lasts several seconds, not less than 2.