Full-Field Characterization of Wishboning Strain in the Colobine Mandibular Symphysis
Article first published online: 16 MAR 2010
Copyright © 2010 Wiley-Liss, Inc.
The Anatomical Record
Special Issue: From Head to Tail: New Models and Approaches in Primate Functional Anatomy and Biomechanics
Volume 293, Issue 4, pages 549–556, April 2010
How to Cite
Bucinell, R. B., Daegling, D. J., Scott Mcgraw, W. and Rapoff, A. J. (2010), Full-Field Characterization of Wishboning Strain in the Colobine Mandibular Symphysis. Anat Rec, 293: 549–556. doi: 10.1002/ar.21120
- Issue published online: 16 MAR 2010
- Article first published online: 16 MAR 2010
- Manuscript Accepted: 11 JAN 2010
- Manuscript Received: 7 JAN 2010
- NSF DUE 0511287
- asymmetric bending;
- Digital Image Correlation
The masticatory loading regime of lateral transverse bending (wishboning) is hypothesized to be instrumental in the evolution of symphyseal form among primates. The biomechanics of wishboning have largely been inferred by assuming that the mandible behaves as a curved beam under this load; however, the characterization of stress and strain in the anthropoid symphysis has been interpretively challenging. This is due, in part, to both limitations of sampling strain in an in vivo context and the incongruence of beam theory assumptions on the one hand, and the anatomical complexity of mandibular morphology on the other. Utilizing three-dimensional (3D) Digital Image Correlation (DIC), we employ an in vitro approach to characterize the strain field in a sample of colobine mandibles under simulated wishboning loads in order to assess the utility of idealized curved beam models for characterizing strain gradients in symphyseal bone. Conventional theory of curved beams suggest that colobine mandibles should exhibit reduced disparity of labial and lingual stresses relative to papionin primates given differences in overall mandibular architecture. This prediction is borne out by our analysis: whereas macaques experience lingual:labial strain disparities of 3.5:1, the colobine mandibles exhibit ratios on the order of 2–3:1. However, despite the fact that wishboning loads represent a case of asymmetric bending, details of the wishboning strain field do not conform to expected stress distribution under this model. Anat Rec, 293:549–556, 2010. © 2010 Wiley-Liss, Inc.