Fig. 1

A coronal schematic representation of the posterior maxillary teeth with the sinonasal complex. Normal mucociliary clearance activity through the maxillary sinus to the osteo-meatal unit is shown as arrows, representative antrochoanal polyps on the superior and medial sinus walls appear dark, and ethmoidal polyps appear as gray asterisks (a). The osteo-meatal unit showing the middle and inferior nasal conchae, uncinate process, and bulla ethmoidale (b)