This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
Posterior ethmoidal sinus opens into 
Select and explain. 
A. Superior nasal meatus, B. Middle nasal meatus, C. Inferior nasal meatus, D. Sphenoethmoidal recess
A: Superior nasal meatus
Answer: A: Superior nasal meatus 
Explanation: The posterior ethmoidal air sinus consisting of 1-7 air cells open into the superior meatus of the nose. It is supplied by the posterior ethmoidal nerve and vessels and the orbital branches of pterygopalatine ganglion. Ref BDC volume 3,6th edition pg 246