title: Innervation of the trapezius muscle: is cervical contribution important to its function?
abstract: OBJECTIVE
  To study the effect of the cervical plexus and the accessory nerve to the function of the trapezius muscle.
  
  
  METHODS
  Eighteen adult male Sprague-Dawley rats were randomly divided into three groups. The neurotomies were performed in the left sides and the right sides served as within-subject controls. In group A, the accessory nerve was transected. The C2-5 were transected in group B, and both of the accessory nerve and C2-5 were cut in group C. The electrophysiologic, myophysiologic, and histologic changes of the muscles were measured.
  
  
  RESULTS
  There were significant differences (P < 0.05) between the three groups in the recovery rates of the transverse area of the muscles. The CMAP recorded from the experimental sides in group B were similar to the control sides. The values of the maximum tension of the tetanus contraction between the two sides showed no differences either (P > 0.05).
  
  
  CONCLUSIONS
  The accessory nerve supplies the most important motor input to the trapezius. Motor innervations of the cervical plexus are not very significant.
authors.affiliation: Department of Oral and Maxillofacial Surgery, The Ninth People's Hospital of Shanghai, School of Stomatology, Shanghai Jiaotong University, Shanghai, PR, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhao
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Zheng
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Yue
authors.initials: Y
authors.lastname: He
authors.forename: Zhi-Yuan
authors.initials: ZY
authors.lastname: Zhang
mesh_terms: D000055:Accessory Nerve / Q000502:physiology; D000818:Animals; D002572:Cervical Plexus / Q000502:physiology*; D004594:Electrophysiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012782:Shoulder / Q000294:innervation*