Research Information System University of Greifswald

Hennig L*¹, Krüger M², Bülow R³, Ittermann T⁴, Ihler F⁵, Krohn F, Krey K⁶, Daboul A²

1 - Zentrum für Zahn-, Mund- und Kieferheilkunde

2 - Zentrum für Zahn-, Mund- und Kieferheilkunde / Poliklinik für Zahnärztliche Prothetik, Alterszahnheilkunde und Medizinische Werkstoffkunde

3 - Zentrum für Radiologie / Institut für Diagnostische Radiologie und Neuroradiologie

4 - Institut für Community Medicine / Abt. SHIP KEF

5 - Klinik und Poliklinik für Hals-Nasen-Ohrenkrankheiten, Kopf- und Halschirurgie

6 - Zentrum für Zahn-, Mund- und Kieferheilkunde / Poliklinik für Kieferorthopädie

Background: The external auditory canal (EAC) exhibits a complex morphology and strong inter-individual variations. However, these have not yet been comprehensively described in the literature. Purpose: This study aims to determine the width, height and cross-sectional area of the cartilaginous portion of the EAC and to describe the three-dimensional morphology and variability of different EACs. Methods: Magnetic resonance imaging was performed on 870 subjects (1740 EACs) who participated in the longitudinal, population-based cohort study ‘Study of Health in Pomerania–START-3’. The height and width were measured in the cartilaginous part of the EAC, between the first and second bend. The variability of the EAC morphology was visualized in three-dimensional models. Results: The mean height (vertical length) of the EAC was 8.62 mm (SD = 2.42) on the right, 8.47 mm (SD = 2.36) on the left. The width (horizontal length) was 4.08 mm (SD = 1.6) on the right, 3.93 mm (SD = 1.64) on the left. The EAC cross-section was 28.6 mm2 (SD = 15.19) on the right, 27.15 mm2 (SD = 14.33) on the left. The average cross-sectional area of the EAC in men was higher than in women. Subjects with larger body size had larger cross-sectional areas. Subjects with higher body mass index tended to have smaller cross-sections. Although the average EAC had an oval shape, a three-dimensional comparison of different EACs revealed strong individual differences in morphology. Conclusion: This study enhances the understanding of otolaryngologists and anatomists regarding the complex morphology and variability of the cartilaginous portion of the EAC.