Biomechanical changes in the rabbit masticatory system during postnatal development
Article first published online: 26 JAN 2005
Copyright © 1991 Wiley-Liss, Inc.
The Anatomical Record
Volume 230, Issue 3, pages 406–416, July 1991
How to Cite
Langenbach, G. E. J., Weijs, W. A. and Koolstra, J. H. (1991), Biomechanical changes in the rabbit masticatory system during postnatal development. Anat. Rec., 230: 406–416. doi: 10.1002/ar.1092300313
- Issue published online: 26 JAN 2005
- Article first published online: 26 JAN 2005
- Manuscript Accepted: 15 NOV 1990
- Manuscript Received: 17 MAY 1990
Using dissection, biometry, and two three-dimensional mechanical models, the postnatal changes of the rabbit masticatory muscles were studied by analyzing their three-dimensional orientation, their strength and fiber lengths, and certain functional consequences of these changes. The first mechanical model uses length-tension relationships of the muscles and predicts the maximum bite force as a function of mandibular position. It shows that young rabbits are able to generate large bite forces at a wider gape than adult animals and that the forces are directed more vertically. In spite of the postnatal changes the mechanical advantage of the system remains about equal. However, the muscles are reoriented so that they exert a larger degree of parallel action, suggesting a larger bite force magnitude but a smaller range of bite force directions. The second model predicts this range. It shows that during postnatal development a relative gain occurs in the possibilities for the system to exert forces directed rostrodorsally. In all other directions the capability to exert force decreases. The results suggest that during development the possibility of the system to generate large bite forces is increased at the cost of a restriction in the range of jaw excursion and that a restriction takes place in the range of possible force directions that can be exerted at the molars.