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Free‐body Diagram Force Analysis in 2D and 3D: A Tool to Study Comparative Vertebrate Biomechanics
Author(s) -
Osborn Michelle L,
Rau A.R.P.,
Ge Jinghua,
Homberger Dominique G.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.577.9
Subject(s) - biomechanics , computer science , diagram , body force , a priori and a posteriori , motion analysis , finite element method , extension (predicate logic) , resultant force , muscular system , simulation , classical mechanics , physics , anatomy , structural engineering , engineering , artificial intelligence , medicine , philosophy , epistemology , database , programming language
Free‐body diagram force analysis is a tried and true method that has been used by physicists and engineers to analyze the forces and torques that act on a physical body. Although this method was adapted to the analysis of skeleto‐muscular systems of vertebrates more than a half century ago, it has rarely been used in analyses of real organisms by functional anatomists, who often rely on intuitive assessments of forces and movements of skeleto‐muscular systems. The reluctance to adopt this more rigorous method of analyzing forces may be based on the fact that the principles of the free‐body diagram force analysis need to be applied to and constructed for each system individually. Our study demonstrates how this analytical method estimates the musculo‐fascial forces of a coherent, complex skeleto‐muscular system based on the known weights of body parts and the measurable geometry of the system, using the human shoulder suspension apparatus as a model. We evaluated the advantages and limitations of the usual application of the free‐body diagram force analysis in 2D and developed an extension of this method into 3D based on reconstructed and visualized x‐ray CT data. Although more complex, the 3D extension of this analysis is more generally applicable and requires fewer a priori assumptions. It also allows for an analysis of the forces acting on a skeletal element with paired joints, such as the skull, as well as for the determination of the center of gravity in 3D models. In addition, this analytical method of static conditions is less involved than methods that analyze dynamic conditions. Taken together, the free‐body diagram force analysis has broad applicability to the comparative biomechanics of vertebrates, as well as to clinical and evolutionary studies, by creating mechanical models whose predictions can be tested via experimental means.