This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head & Neck, Subject name: Anatomy
Sphenoid sinus drains into? 
Select and explain. 
A. Sphenoethmoidal recess, B. Middle Meatus, C. Superior meatus, D. Inferior meatus
A: Sphenoethmoidal recess
Answer: A: Sphenoethmoidal recess 
Explanation: Ans. A. Sphenoethmoidal recessThe lateral wall of nasal cavity presents three medial projections called conchae, which overlies meatuses. The sphenoethmoidal recess, above and posterior to the superior concha, receives the opening of the sphenoidal sinus. The superior meatus, under cover of the superior concha, receives the openings of the posterior ethmoidal cells. The middle meatus receives the opening of maxillary, frontal, anterior ethmoidal and posterior ethmoidal sinuses. The inferior meatus receives the opening of nasolacrimal duct.