Ostium maxillare

Below the bulla ethmoidalis, and partly hidden by the inferior end of the uncinate process, is the maxillary hiatus (or ostium maxillare, or maxillary sinus ostium, or maxillary ostium, or opening from the maxillary sinus); in a frontal section this opening is seen to be placed near the roof of the sinus.

Additional images
Below the bulla ethmoidalis, and partly hidden by the inferior end of the uncinate process, is the ostium maxillare (or maxillary sinus ostium, or maxillary ostium, or opening from the maxillary sinus); in a frontal section this opening is seen to be placed near the roof of the sinus.