FRONTAL-SINUS OUTFLOW ANATOMY

Most of the studies of frontal sinus anatomy were completed 50 to 70 y ears ago. The information they provide is not necessarily relevant or helpful to the modem rhinologic surgeon who approaches the frontal sin us transnasally and endoscopically. We performed anatomical dissection s of the outflow tract of 82 frontal sinuses in 41 cadaver heads to il lustrate the various drainage patterns from the frontal sinus to the n ose and to correlate these drainage sites with the distance and angle from the pyriform aperture. We found that the frontal sinus drained an terior to the uncinate process in 24 specimens (29.3%) with an average distance of 3.65 cm from the pyriform aperture and 58 degrees from th e nasal floor. The frontal sinus drained posterior-to the uncinate pro cess in 56 specimens (68.3%) with an average distance of 4.10 cm and 6 5 degrees from the nasal floor In this latter group, most of the sinus es (51 specimens) drained into the ethmoid infundibulum. Two of the sp ecimens had a hypoplastic frontal sinus with no outflow tract at all. These findings are different from those described in the early 20th ce ntury.