title: Quantitative Evaluation of the In Vivo Vocal Fold Medial Surface Shape.
abstract: OBJECTIVE
  Glottal insufficiency is a common clinical problem in otolaryngology and medialization laryngoplasty (ML) procedures remain the primary treatment modality. Although the goal of ML is to restore physiologic glottal posture and achieve optimal phonation, this posture has not been directly measured. In this study, we assessed glottal medial surface contour changes with selective activation of the intrinsic laryngeal muscles (ILMs).
  
  
  METHODS
  Basic science study using an in vivo canine hemilarynx model.
  
  
  METHODS
  In an in vivo canine hemilarynx, India ink was used to mark fleshpoints in a grid-like fashion along the medial surface of the vocal fold and ILMs were activated in a graded manner. A right-angled prism provided two views of the medial surface, which were recorded using a high-speed camera and used to reconstruct the 3D posture deformations of the medial surface.
  
  
  RESULTS
  Thyroarytenoid (TA) muscle activation results in initial inferomedial bulging and increased glottal channel thickness and then glottal adduction with a final rectangular glottal channel shape. Lateral cricoarytenoid (LCA) activation closes the posterior glottis but final posture remains slightly convergent. Together, TA + LCA forms a rectangular glottis with an increased glottal vertical thickness. Posterior cricoarytenoid activation results in abduction and a slightly divergent glottis, whereas cricothyroid activation elongates the glottis and reduces the glottal channel vertical thickness.
  
  
  CONCLUSIONS
  A quantitative analysis of in vivo canine vocal fold medial surface upon activation of selective ILMs is provided. This may guide our therapeutic efforts during medialization laryngoplasty, as well as computational modeling of laryngeal physiology.
authors.affiliation: Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California. Electronic address: AVahabzadehHagh@mednet.ucla.edu.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Vahabzadeh-Hagh
authors.affiliation: Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Zhaoyan
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Dinesh K
authors.initials: DK
authors.lastname: Chhetri
mesh_terms: D000818:Animals; D004285:Dogs; D066298:In Vitro Techniques; D007821:Laryngeal Muscles / Q000000981:diagnostic imaging / Q000502:physiology*; D014827:Vocal Cords / Q000000981:diagnostic imaging / Q000502:physiology*
keywords: Canine; Larynx; Prephonatory posture; Vocal fold; Vocal fold medial surface shape