Frontonasal duct

The frontonasal duct is a duct through which either frontal sinus drains into the nasal cavity. Each frontal sinus opens into the frontonasal duct by an opening (the opening of frontal sinus or frontal sinus aperture) on the inferomedial part of the floor of the sinus. The frontonasal duct passes inferior-ward to open either into the middle nasal meatus at the anterior end of the ethmoidal infundibulum, or into the anterior ethmoidal air cells (which then in turn drain into the nasal cavity).

The duct is lined by mucous membrane.