Anatomic Confirmation of the Motor Fibers in the Cervical Nerves Innervating to the Trapezius Muscle

Woo, Jung Su; Hur, Mi Sun; Kang, Bum Seung; Park, Seon Young; Lee, Kyu Seok

Abstract

This study aimed to confirm the presence of motor fibers in the cervical nerves distributing to the trapezius muscle. Thirteen cases were examined. Motor fibers were present in C3 in 7 of 9 cases (77.8%) and were absent in 2 of 9 cases (22.3%); the other 4 cases were damaged during dissection. C4 exhibited motor fibers in 9 of 10 cases (90.0%), whereas motor fibers were absent in 1 of 10 cases (10.0%); and 3 cases were damaged. The motor fibers in C3 were of medium size (57.1%; 4/7 cases), whereas those in C4 were large (44.4%; 4/9 cases). The average number of motor fibers in C3 and C4 were 114+/-112 and 219+/-167, respectively. These results show that C4 is more important in terms of the frequency and size of the cervical motor fibers distributing to the trapezius muscle.