Abstract
[Purpose] The purpose of this study was to investigate for the validity of the attachment sites of surface electromyograph electrodes used to measure intrinsic back muscles. [Subjects] The subjects were 20 healthy young males. [Methods] Ultrasonograms of the intrinsic back muscles were recorded at four sites: 3 cm and 6 cm lateral from L2 and the L4 spinous processes in the prone position. The distances of both lateral borders and the most superficial layer of the transversospinalis muscle from the spinous processes were measured at each site. [Results] In the young Japanese male subjects, the transversospinalis muscle was not identified in many cases at 3 cm lateral from both the L2 and the L4 spinous processes. At 3 cm lateral from the L2 and the L4 levels, the longissimus muscle was identified. At 6 cm lateral side from the L2 and the L4 levels, the ilicostalis muscle was identified. [Conclusion] It is possible that the muscle activity of the multifidus muscle may not be measured at 3 cm laterally from the L2 and the L4 levels by surface electoromyography. Therefore, it may be necessary to reconsider the electrode attachment site used in previous research.
