system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
59-year-old man has difficulty in breathing through his nose. On examination, his physician finds that he has swelling of mucous membranes of the superior nasal meatus. Which opening of the paranasal sinuses is most likely plugged?
assistant
The correct answer is  Posterior ethmoidal sinus opens into the superior nasal meatus. Maxillary, frontal, and anterior and middle ethmoidal sinuses drain into middle nasal meatus.