STUDY DESIGN: Accurate determination of the three-dimensional coordinates of paraspinal muscles is presented. OBJECTIVES: To determine the precise position and the size of the paraspinal muscles. SUMMARY OF BACKGROUND DATA: The accurate measurements of the muscle moment arms are important in the evaluation of computer models for spinal movement. It has been reported that a change in the modelling of the erector spinae muscles can alter the compressive forces in the spinal column by 20% and can increase the offsetting shear forces. Classic studies used measurements from cross-sectional anatomic diagrams of human cadavers, scaled to the width and depth of the trunk of the subject, to calculate the moment that produces the joint torque. METHODS: Computed tomography scans of two male cadavers provided data on the bony elements. Three-dimensional coordinates of the origins and insertions of the muscle-fascicles of the paraspinal muscles were obtained with the use of 3-Space Isotrak equipment. The bony and muscle coordinates were combined in the ANSYS (version 5.4; Swanson Analysis Systems, Canonsberg, PA) program. RESULTS: Results of this combination and the three-dimensional coordinates of the paraspinal muscles as acquired by the 3-Space Isotrak are given. CONCLUSION: The position and the moment arms of paraspinal muscles were accurately determined. This is important for further evaluation of mathematical models.
STUDY DESIGN: Accurate determination of the three-dimensional coordinates of paraspinal muscles is presented. OBJECTIVES: To determine the precise position and the size of the paraspinal muscles. SUMMARY OF BACKGROUND DATA: The accurate measurements of the muscle moment arms are important in the evaluation of computer models for spinal movement. It has been reported that a change in the modelling of the erector spinae muscles can alter the compressive forces in the spinal column by 20% and can increase the offsetting shear forces. Classic studies used measurements from cross-sectional anatomic diagrams of human cadavers, scaled to the width and depth of the trunk of the subject, to calculate the moment that produces the joint torque. METHODS: Computed tomography scans of two male cadavers provided data on the bony elements. Three-dimensional coordinates of the origins and insertions of the muscle-fascicles of the paraspinal muscles were obtained with the use of 3-Space Isotrak equipment. The bony and muscle coordinates were combined in the ANSYS (version 5.4; Swanson Analysis Systems, Canonsberg, PA) program. RESULTS: Results of this combination and the three-dimensional coordinates of the paraspinal muscles as acquired by the 3-Space Isotrak are given. CONCLUSION: The position and the moment arms of paraspinal muscles were accurately determined. This is important for further evaluation of mathematical models.