Innervation of the trapezius muscle: is cervical contribution important to its function?
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.
Zhao
Wen
W
Department of Oral and Maxillofacial Surgery, The Ninth People's Hospital of Shanghai, School of Stomatology, Shanghai Jiaotong University, Shanghai, PR, China.
Sun
Jian
J
Zheng
Jia-Wei
JW
Li
Jun
J
He
Yue
Y
Zhang
Zhi-Yuan
ZY
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*