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
All drains into middle meatus except:
assistant
The correct answer is  Anterior group of paranasal sinus which includes maxillary, frontal and anterior ethmoidal. They all open in the middle meatus and their ostia lie anterior to basal lamella of middle turbinate Ref: Dhingra 7e pg 209.