title: Timing of glottic closure during swallowing: a combined electromyographic and endoscopic analysis.
abstract: OBJECTIVE
  We performed a case series to enhance our understanding of the coupling between neuromuscular events and glottic closure.
  
  
  METHODS
  We performed combined flexible video laryngoscopy and electromyography in 4 healthy human subjects. Hooked-wire electrodes were placed in the superior pharyngeal constrictor, longitudinal pharyngeal, cricopharyngeus, thyroarytenoid, genioglossus, suprahyoid, and posterior cricoarytenoid muscles. A flexible endoscope tip was positioned in the oropharyngeal-hypopharyngeal region. The subjects performed multiple trials each of 10-mL normal and super-supraglottic liquid swallows.
  
  
  RESULTS
  Arytenoid movement consistently preceded full glottic closure and was associated with cessation of activity of the posterior cricoarytenoid muscle. In 89% of normal swallows, the glottis was partially open in the video frame before bolus passage. The maximum amount of thyroarytenoid electromyographic activity occurred during endoscopic whiteout. When subjects executed a super-supraglottic swallow, early thyroarytenoid activity coincided with arytenoid contact.
  
  
  CONCLUSIONS
  The initial medialization of the arytenoids is due to a decrease in motor tone of the posterior cricoarytenoid muscle. Full glottic closure typically occurs late in the process of swallowing, with activation of the thyroarytenoid muscle. Shifting of arytenoid medialization and glottic closure earlier in the super-supraglottic swallow indicates that glottic closure is under significant voluntary control.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242-1078, USA.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Van Daele
authors.forename: Timothy M
authors.initials: TM
authors.lastname: McCulloch
authors.forename: Phyllis M
authors.initials: PM
authors.lastname: Palmer
authors.forename: Susan E
authors.initials: SE
authors.lastname: Langmore
mesh_terms: D000328:Adult; D003679:Deglutition / Q000502:physiology*; D004576:Electromyography; D005260:Female; D005336:Fiber Optic Technology; D005931:Glottis / Q000502:physiology*; D006801:Humans; D007821:Laryngeal Muscles / Q000502:physiology; D007828:Laryngoscopy; D008297:Male; D010609:Pharyngeal Muscles / Q000502:physiology; D014741:Video Recording