5. Remove the conchae to expose the meatuses, the ethmoidal bulla, hiatus semilunaris and the openings of the sinuses.

Next, remove the inferior and middle conchae. Notice the semilunar hiatus in the middle meatus and the ethmoid bulla above it. The anterior ethmoidal air cells drain into the hiatus. The hiatus is also connected to the frontal sinus by the frontonasal duct. The middle ethmoid air cells drain into the ethmoidal bulla. The maxillary sinus also drains into the semilunar hiatus here, posteriorly. In the inferior nasal meatus, the pin is in the opening of the nasolacrimal duct, draining the lacrimal sac near the eye into the nasal cavity. This was mislabeled in the video. The sphenoid sinus drains into the sphenoethmoidal recess. The nasolacrimal duct can be opened more completely by breaking its bony covering. Next, remove the lateral wall of the nasal cavity to explore the sinuses. Note the middle and posterior ethmoid air cells.