Anatomical Landmarks for Locating the Sphenoid Ostium: A Cadaveric Study

Purpose: Localization of the sphenoid ostium (SO) is essential for entering the sphenoid sinus. The present study was designed to establish readily identifiable anatomical landmarks for locating the sphenoid ostium.

Methods: Cadaveric dissection was performed in 30 hemisections of head and neck. The size, shape, and position of the sphenoid ostium were determined in relation to the anterior wall of the sphenoid sinus and the superior turbinate.

Results: The mean distance from the superolateral angle of the posterior choana to the SO was found to be 21.21 ± 6.02 mm. The mean distance of the SO from the midline was 4.85 ± 2.89 mm. In all the specimens, the SO was situated within 1 cm of the midline. The mean distance between the inferior end of the SO and the posteroinferior edge of the superior turbinate was 8.03 ± 3.52 mm. The SO was present on an average distance of 55.1 ± 3.54 mm from the limen nasi. In 93.3% of the specimens the SO was situated between 5 cm and 6 cm of the inferior end of the limen nasi.

Conclusions: The sphenoid ostium could be localized medial to the superior turbinate between 1.5 and 3 cm above the superolateral angle of the posterior choana, within 1 cm of the midline and within 1 cm of the posteroinferior edge of the superior turbinate.