The anisotropic nature of the vocal fold

A.-K. Licht, E. Goodyer, F. Müller, JB Kobler, M. Hess

Introduction: The viscoelastic properties of the vocal fold tissue provide the biomechanical means to support the oscillatory motion for phonation. The set goal of this work was to determine layer dependent and directional variations of the elastic properties of the vocal fold, in short the anisotropic behaviour.
Materials and methods: 14 excised human larynges were split along the sagittal plane, mounted without tension, and measured each semilarynx using a Linear Skin Rheometer (LSR). The LSR-probe was attached primarily to the vocal fold epithelium mid-membranous between the anterior commissure and vocal process using a round suction catheter of 2.7 mm outer diameter. The elastic response was measured by applying stress at 5 different angles. Additional measurements were made in a similar procedure for lamina propria, ligament and muscle.
Results: The distribution of anisotropy between the different angles and the single layers will be demonstrated.
Conclusion: The range of shear modulus derived using this method is comparable to that obtained by our team in-vitro in a previous published study and by other research groups obtained in-vivo or in-vitro. In addition to the confirmation of previous results we highlight an anisotropic nature of the vocal fold tissue.

A.-K. Licht*, E. Goodyer^#, F. Müller*, JB Kobler^?, M Hess*
*Department of voice, speech and hearing disorders, University Medical Centre Hamburg-Eppendorf, Germany, ^# The Centre for Computational Intelligence-Bioinformatics Group, DeMontfort University, Leicester, UK, ^? Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston, MA, USA
Frank Müller f.mueller@uke.uni-hamburg.de