Organ system anatomy · USMLE Step 1

A patient has difficulty swallowing solids and liquids. Dysfunction of which muscular structure is most likely involved?

  1. Upper esophageal sphincter
  2. Lower esophageal sphincter
  3. Pharyngotympanic tube
  4. Cricothyroid muscle
Show answer and explanation

Correct answer: Upper esophageal sphincter

The upper esophageal sphincter, formed primarily by the cricopharyngeus muscle, regulates entry into the esophagus. Dysfunction causes dysphagia.

Difficulty: Medium Question 15 of 20

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