title: The Dilator Naris Muscle as a Reporter of Facial Nerve Regeneration in a Rat Model.
abstract: OBJECTIVE
  Many investigators study facial nerve regeneration using the rat whisker pad model, although widely standardized outcomes measures of facial nerve regeneration in the rodent have not yet been developed. The intrinsic whisker pad "sling" muscles producing whisker protraction, situated at the base of each individual whisker, are extremely small and difficult to study en bloc. Here, we compare the functional innervation of 2 potential reporter muscles for whisker pad innervation: the dilator naris (DN) and the levator labii superioris (LLS), to characterize facial nerve regeneration.
  
  
  METHODS
  Motor supply of the DN and LLS was elucidated by measuring contraction force and compound muscle action potentials during stimulation of individual facial nerve branches, and by measuring whisking amplitude before and after DN distal tendon release.
  
  
  RESULTS
  The pattern of DN innervation matched that of the intrinsic whisker pad musculature (ie, via the buccal and marginal mandibular branches of the facial nerve), whereas the LLS seemed to be innervated almost entirely by the zygomatic branch, whose primary target is the orbicularis oculi muscle.
  
  
  CONCLUSIONS
  Although the LLS has been commonly used as a reporter muscle of whisker pad innervation, the present data show that its innervation pattern does not overlap substantially with the muscles producing whisker protraction. The DN muscle may serve as a more appropriate reporter for whisker pad innervation because it is innervated by the same facial nerve branches as the intrinsic whisker pad musculature, making structure/function correlations more accurate, and more relevant to investigators studying facial nerve regeneration.
authors: From the *Department of Otolaryngology/Head and Neck Surgery, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, MA; †Department of Otorhinolaryngology/Head and Neck Surgery, Radboud University Medical Center, Nijmegen, the Netherlands; and ‡Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
authors: Julie S
authors: JS
authors: Weinberg
authors: Ingrid J
authors: IJ
authors: Kleiss
authors: Christopher J
authors: CJ
authors: Knox
authors: James T
authors: JT
authors: Heaton
authors: Tessa A
authors: TA
authors: Hadlock
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004576:Electromyography; D005152:Facial Muscles / Q000294:innervation / Q000601:surgery* / Q000637:transplantation; D005154:Facial Nerve / Q000601:surgery*; D005158:Facial Paralysis / Q000601:surgery*; D005260:Female; D009416:Nerve Regeneration / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D014738:Vibrissae / Q000294:innervation
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