title: Comparison of muscle activity between subjects with or without lip competence: Electromyographic activity of lips, supra- and infrahyoid muscles.
abstract: OBJECTIVE
  This study compares the electromyographic (EMG) activity of the muscles from the lips and hyoid bone in subjects with or without lip competence.
  
  
  METHODS
  Two groups of 20 subjects each, with or without lip competence were studied. EMG activity of the superior orbicularis oris (SOO), inferior orbicularis oris (IOO), suprahyoid (SH) and infrahyoid (IH) muscles was recorded with the subject seated in the upright position during the following tasks: (1) at rest; (2) speaking; (3) swallowing; (4) forced deep breathing; (5) maximal voluntary clenching; and (6) chewing.
  
  
  RESULTS
  EMG activity was significantly higher in subjects without competent lips than with competent lips in the SOO and IOO muscles during tasks 3 and 4, SOO during task 2 and IOO during task 6. EMG activity was similar in the SOO and IOO muscles during tasks 1 and 5, SOO during task 6 and IOO during task 2. Activity of the SH and IH muscles was similar in both groups for all tasks.
  
  
  CONCLUSIONS
  Higher activity in subjects without competent lips implies a higher muscular effort due to the requirement of lip sealing during functional activities. Hyoid muscular activity was not modified by the presence or absence of lip competence.
authors.affiliation: a Faculty of Dentistry , Institute for Research in Dental Sciences, University of Chile , Santiago , Chile.|b Oral Physiology Laboratory, Faculty of Medicine , Biomedical Sciences Institute, University of Chile , Santiago , Chile.
authors.forename: Natalia Andrea
authors.initials: NA
authors.lastname: Gamboa
authors.affiliation: b Oral Physiology Laboratory, Faculty of Medicine , Biomedical Sciences Institute, University of Chile , Santiago , Chile.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Miralles
authors.affiliation: a Faculty of Dentistry , Institute for Research in Dental Sciences, University of Chile , Santiago , Chile.|b Oral Physiology Laboratory, Faculty of Medicine , Biomedical Sciences Institute, University of Chile , Santiago , Chile.
authors.forename: Saúl
authors.initials: S
authors.lastname: Valenzuela
authors.affiliation: b Oral Physiology Laboratory, Faculty of Medicine , Biomedical Sciences Institute, University of Chile , Santiago , Chile.
authors.forename: Hugo
authors.initials: H
authors.lastname: Santander
authors.affiliation: a Faculty of Dentistry , Institute for Research in Dental Sciences, University of Chile , Santiago , Chile.|b Oral Physiology Laboratory, Faculty of Medicine , Biomedical Sciences Institute, University of Chile , Santiago , Chile.|c Faculty of Medicine , Diego Portales University , Santiago , Chile.
authors.forename: Rosa
authors.initials: R
authors.lastname: Cordova
authors.affiliation: b Oral Physiology Laboratory, Faculty of Medicine , Biomedical Sciences Institute, University of Chile , Santiago , Chile.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Bull
authors.affiliation: a Faculty of Dentistry , Institute for Research in Dental Sciences, University of Chile , Santiago , Chile.
authors.forename: Diego Alejandro
authors.initials: DA
authors.lastname: Espinoza
authors.affiliation: a Faculty of Dentistry , Institute for Research in Dental Sciences, University of Chile , Santiago , Chile.
authors.forename: Catalina Andrea
authors.initials: CA
authors.lastname: Martínez
mesh_terms: D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D004576:Electromyography; D005152:Facial Muscles / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006928:Hyoid Bone / Q000503:physiopathology*; D008046:Lip / Q000503:physiopathology*; D008297:Male
keywords: Superior orbicularis oris; competent/incompetent lips; electromyography; inferior orbicularis oris; seated upright position; supra- and infrahyoid muscles