title: The anisotropic nature of the human vocal fold: an ex vivo study.
abstract: The purpose of this study was to measure the relationship between the shear elastic properties of vocal fold with respect to the direction of applied stress. There is extensive published material that quantifies the shear viscoelastic properties of the vocal fold, but as much of these data were obtained using rotating parallel plate rheometers, which are unable to resolve out difference of the shear elastic behaviour with respect to direction, there is very little data that indicates anisotropic behaviour. To overcome this gap in knowledge, the team devised an apparatus that is capable of applying a shear stress in a known direction. A series of measurements were taken at the mid-membranous position, in the transverse and longitudinal directions. Point-specific measurements were performed using fourteen human cadaver excised larynges, which were hemi-sectioned to expose the vocal fold. An extremely low sinusoidal shear force of 1 g was applied tangentially to the membrane surface in both the longitudinal and transverse direction, and the resultant shear strain was measured. With the probe applied to the intact vocal fold, the average ratio of the elasticity in the transverse with respect to the longitudinal direction was 0.55. Further investigation using histological staining of collagens in the lamina propria indicates that there is a visible difference in the general alignment of collagen fibres when comparing the coronal and the sagittal sections. Our conclusion is that there is a quantifiable difference between the shear elastic response of the lamina propria in the longitudinal and transverse directions, and that this could be explained by the difference in alignment of collagen fibres within the lamina propria.
authors.affiliation: Department of Voice, Speech and Hearing Disorders, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. a.rohlfs@uke.de
authors.forename: Anna-Katharina
authors.initials: AK
authors.lastname: Rohlfs
authors.forename: Eric
authors.initials: E
authors.lastname: Goodyer
authors.forename: Till
authors.initials: T
authors.lastname: Clauditz
authors.forename: Markus
authors.initials: M
authors.lastname: Hess
authors.forename: Malte
authors.initials: M
authors.lastname: Kob
authors.forename: Susan
authors.initials: S
authors.lastname: Koops
authors.forename: Klaus
authors.initials: K
authors.lastname: Püschel
authors.forename: Frank W
authors.initials: FW
authors.lastname: Roemer
authors.forename: Frank
authors.initials: F
authors.lastname: Müller
mesh_terms: D000368:Aged; D016880:Anisotropy; D001696:Biomechanical Phenomena; D002102:Cadaver; D004548:Elasticity; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D009092:Mucous Membrane / Q000502:physiology; D013314:Stress, Mechanical; D014783:Viscosity; D014827:Vocal Cords / Q000502:physiology*
references.citation: Ultrasound Med Biol. 2002 Sep;28(9):1145-52
references.pmid: 12401384
references.citation: Otolaryngol Head Neck Surg. 2002 May;126(5):528-37
references.pmid: 12075228
references.citation: Eur Arch Otorhinolaryngol. 2007 Jun;264(6):631-5
references.pmid: 17285333
references.citation: Folia Phoniatr Logop. 2006;58(3):207-16
references.pmid: 16636568
references.citation: Ann Otol Rhinol Laryngol. 1993 Aug;102(8 Pt 1):584-91
references.pmid: 8352480
references.citation: Eur Arch Otorhinolaryngol. 2007 Jan;264(1):45-50
references.pmid: 16924433
references.citation: Ultrasound Med Biol. 2001 Aug;27(8):1035-40
references.pmid: 11527589
references.citation: J Voice. 2010 Jul;24(4):494-8
references.pmid: 19487101
references.citation: Laryngoscope. 1992 Jul;102(7):760-9
references.pmid: 1614247
references.citation: Eur Arch Otorhinolaryngol. 2001 Mar;258(3):125-9
references.pmid: 11374253
references.citation: J Acoust Soc Am. 1999 Oct;106(4 Pt 1):2008-21
references.pmid: 10530024
references.citation: Clin Exp Otorhinolaryngol. 2010 Dec;3(4):177-82
references.pmid: 21217957
references.citation: Acta Otolaryngol. 2006 Jul;126(7):758-63
references.pmid: 16803717
references.citation: J Speech Hear Res. 1984 Jun;27(2):212-9
references.pmid: 6738032
references.citation: Ann Otol Rhinol Laryngol. 1997 Jan;106(1):44-8
references.pmid: 9006361
references.citation: PLoS One. 2011;6(11):e27029
references.pmid: 22073246
references.citation: J Biomed Mater Res. 2000;53(6):646-50
references.pmid: 11074422
references.citation: J Acoust Soc Am. 1991 Sep;90(3):1326-31
references.pmid: 1939897
references.citation: J Acoust Soc Am. 2000 Jan;107(1):565-80
references.pmid: 10641665
references.citation: J Biomech. 2012 Nov 15;45(16):2943-6
references.pmid: 23021593
references.citation: Ann Biomed Eng. 2003 Apr;31(4):482-91
references.pmid: 12723689
references.citation: J Biomech. 2005 Nov;38(11):2248-56
references.pmid: 16154412
references.citation: Phonetica. 1973;28(3):129-70
references.pmid: 4788091
references.citation: Ann Otol Rhinol Laryngol. 1995 Jul;104(7):563-9
references.pmid: 7598370
references.citation: Phonetica. 1974;29(1):1-21
references.pmid: 4823344
references.citation: J Voice. 2006 Sep;20(3):432-42
references.pmid: 16324825
references.citation: Laryngoscope. 1992 Jul;102(7):770-8
references.pmid: 1614248
references.citation: Biomech Model Mechanobiol. 2013 Jun;12(3):555-67
references.pmid: 22886592
references.citation: Tissue Eng. 2006 Nov;12(11):3201-7
references.pmid: 17518634
references.citation: J Acoust Soc Am. 2008 Aug;124(2):1207-19
references.pmid: 18681608
references.citation: Laryngoscope. 2011 Apr;121(4):785-92
references.pmid: 21287562
references.citation: J Voice. 2009 Mar;23(2):143-50
references.pmid: 17485196
references.citation: Laryngoscope. 2009 May;119(5):1033-41
references.pmid: 19274731
references.citation: Ann Otol Rhinol Laryngol. 2002 Jan;111(1):15-20
references.pmid: 11800365