The maxillary sinus opens into middle meatus at the level of:
The maxillary sinus is the largest of the paranasal sinuses and is located in the maxilla, lateral to the nasal cavity and inferior to the orbit. The maxillary sinus opens into the posterior aspect of the hiatus semilunaris in the middle meatus. The infraorbital nerve (CN V-2) primarily innervates the maxillary sinus.
Hiatus semilunaris
Bulla ethmoidalis
Infundibulum
None of the above