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Imaging and Modeling Techniques
Techniques for Modeling Muscle-induced Forces in Finite Element Models of Skeletal Structures
Article first published online: 23 AUG 2007
Copyright © 2007 Wiley-Liss, Inc.
The Anatomical Record
Volume 290, Issue 9, pages 1069–1088, September 2007
How to Cite
Grosse, I. R., Dumont, E. R., Coletta, C. and Tolleson, A. (2007), Techniques for Modeling Muscle-induced Forces in Finite Element Models of Skeletal Structures. Anat Rec, 290: 1069–1088. doi: 10.1002/ar.20568
- Issue published online: 23 AUG 2007
- Article first published online: 23 AUG 2007
- Manuscript Accepted: 4 JUN 2007
- Manuscript Received: 27 FEB 2007
- NSF. Grant Numbers: IOB 0447616, EAR-0236775
- finite element analysis;
- muscle force;
- muscle loading alogorithm, biting
This work introduces two mechanics-based approaches to modeling muscle forces exerted on curvilinear bone structures and compares the results with two traditional ad hoc methods of muscle loading. These new models use a combination of tensile, tangential, and normal traction loads to account for muscle fibers wrapped around curved bone surfaces. A computer program was written to interface with a commercial finite element analysis tool to automatically apply traction loads to surface faces of elements in muscle attachment regions according to the various muscle modeling methods. We modeled a highly complex skeletal structure, the skull of a Jamaican fruit bat (Artibeus jamaicensis), to compare the four muscle-loading methods. While reasonable qualitative agreement was found in the states of stress of the skull between the four muscle load modeling methods, there were substantial quantitative differences predicted in the stress states in some high stressed regions of the skull. Furthermore, our mechanics-based models required significantly less total applied muscle force to generate a bite-point reaction force identical to those produced by the ad hoc muscle loading models. Although the methods are not validated by in vivo data, we submit that muscle-load modeling methods that account for the underlying physics of muscle wrapping on curved bone surfaces are likely to provide more realistic results than ad hoc approaches that do not. We also note that, due to the geometric complexity of many bone structures—such as the skull analyzed here—load transmission paths are difficult to conceptualize a priori. Consequently, it is difficult to predict spatially where the results of finite element analyses are likely to be compromised by using ad hoc muscle modeling methods. For these reasons, it is recommended that a mechanics-based method be adopted for determination of the proper traction loads to be applied to skeletal structures due to muscular activity. Anat Rec, 290:1069–1088, 2007. © 2007 Wiley-Liss, Inc.