Morphological Analysis of the Adult Eustachian Tube: A Fresh-Frozen Human Cadaver Study

Objectives: To evaluate the dilated Eustachian tube (ET) anatomy configuration using fresh human cadavers. Methods: Fourteen ears from human cadavers were used to identify the ET configuration. The cadaver head was cut in the sagittal plane parallel to the nasal septum, dividing it into right and left sides. Silicone was then inserted into the ET through the nasopharyngeal orifice (NO). The volume and length of the impression were measured using 3D computed tomography imaging. Results: The ET lumen was found to narrow from the NO to the isthmus, and the ET surface was concave anteriorly and convex posteriorly. The lower portion of the ET lumen was the most dilated and displayed a narrow top. The average volume of the ET impression was 1.4 ± 0.5 ml. The total length of the posterior side was 30.5 ± 3.6 mm, and that of the anterior side was 26.3 ± 3.4 mm. The widest ET area of the NO was 10.1 ± 0.9 mm in height and 8.0 ± 1.5 mm in width. The preisthmus was 2.4 ± 0.4 mm in height and 1.3 ± 0.5 mm in width. The height and width were 8.37 and 5.33 mm at the 5 mm point from the NO, and 5.51 and 1.94 mm at the 20 mm point from the NO, respectively. Conclusion: We evaluated the configuration of the cartilaginous ET lumen, which is the main target of balloon dilation, and our findings may give insights into this dilation process and assist with the further development of ET balloons and stents.