Cadaveric Anatomy of Frontal Sinus Outflow Pathway

Background: Cadaveric anatomy of the frontal sinus may be useful to endoscopic surgeons during treatment of diseases related to frontal sinus drainage.

Material and Methods: For this report, 32 mid-sagittal cadaveric heads were studied. The following parameters were recorded: drainage site of the sinus in relation to the uncinate process, attachment of the uncinate process, pneumatization of the agger nasi, and morphometric measurements for localization of the frontal ostium during endoscopic surgery.

Results: The frontal sinus drainage was anterior to the uncinate process in 59.4% and posterior to it in 40.6%. In a majority of cases (59.4%), the uncinate process was found attached to the lamina papyracea. The mean diameter of the frontal ostium was 4.6 ± 1.6 mm. The angle formed by the plane of frontal ostium to the floor of the nose was 26 ± 5.9 degrees; distance of the frontal beak to the anterior nasal spine was 46.5 ± 5.7 mm, and the distance of the frontal beak from the columella was 48.7 ± 4.8 mm. The corresponding angle between the frontal beak and the nasal floor (at the anterior nasal spine) was 70 ± 5 degrees, but this decreased to 56.6 ± 7.5 degrees when the columella was the reference point. Pneumatization of the agger nasi was seen in 90% of specimens. The mean distance of the anterior ethmoidal artery was 9.0 ± 1.2 mm from the frontal beak and 8.4 ± 1.8 mm from the posterior rim of the frontal ostium.

Conclusions: Cadaveric data will be of help in endoscopic surgery for accurate and safe negotiation of the frontal sinus drainage tract.