All open into hiatus semilunaris except: (A) Posterior ethmoid sinus, (B) Anterior ethmoid sinus, (C) Frontal sinus, (D) Maxillary sinus
Answer is A. Hiatus semilunaris. The hiatus semilunaris is a semicircular shaped openinglocated on the lateral wall of the nasal cavity. It is a component of the ostiomeatal complex and serves as the opening for the frontal and maxillary sinuses and the anterior ethmoid air cells.