Fig. 1.

Mechanism and sequence of irrigation of the nasal cavity and nose. (A) The diagram showing the location and relationship of each sinus and nasal cavity. (B-H) The irrigation fluid first hits the nasopharynx and then indirectly enters the sinus. According to cadaveric and threedimensional modeling studies, the fluid first passes through the ethmoid and nasopharynx, then the ipsilateral maxillary and sphenoid sinuses, followed by the frontal sinus and then the opposite side of the maxillary sinus.