2006 Volume 18 Pages 241-250
A muscle active simulator for cadaveric lumbar experiments was developed. This simulator can generate wire tensions as the complex and continuous muscle forces of 7 muscles in lumbar spine;m. rectus abdominis, m. obliquus internus abdominis, m. obliquus externus abdominis and m. erector spinae. The wire tensions were controlled by servo actuators consisting of stepper motors and loadcells. The muscle tensions were obtained by a musculoskeletal lumboligamentous model and actual motion data. The maximum tension was limited to 100 N to avoid damaging cadavers. Under the muscle tensions of the flexion 30 [deg], the extension 20 [deg], the lateral bending 20 [deg] and the axial rotation 10 [deg], the motions of two fresh cadaveric lumbar spines were almost similar to theactual motion. The lumbar spine bent laterally even in the flexion motion because of the asymmetry spinal shape. When the lumbar spines bent laterally, L5 vertebra bent reversely. In the axial rotation, L1 rotated the most. L2-L3 moved as one unit, but L5 fixed on the sacrum and L3 bent laterally because of the wedge shape of intervertebral discs.
