frontonasal duct

In slightly over 50% of subjects, this is directly continuous with the frontonasal duct from the frontal air sinus.

The frontonasal duct is a communication between the frontal air sinuses and their corresponding nasal cavity.

Following the curve anteriorly leads into the infundibulum of the frontonasal duct, which drains the frontal sinus.

They are lined by mucous membrane, and each communicates with the corresponding nasal cavity by means of a passage called the frontonasal duct.

Each opens into the anterior part of the corresponding superior meatus of the nose through the frontonasal duct which traverses the anterior part of the labyrinth of the ethmoid.

When the anterior end of the uncinate process fuses with the front part of the bulla, however, this continuity is interrupted and the frontonasal duct then drains directly into the anterior end of the middle meatus.