Regional Tongue Deformations during Chewing and Drinking in the Pig

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As a muscular hydrostat, the tongue undergoes complex deformations during most oral behaviors, including chewing and drinking. During thesebehaviors, deformations occur in concert with tongue and jaw movements to position and transport the bolus. Moreover, the various parts of the tongue may move and deform at similar timepoints relative to the gape cycle or they may occur at different timepoints, indicating regional biomechanical and functional variation. The goal of this study is to quantify tongue deformations during chewing and drinking in pigs by characterizing intrinsic changes in tongue dimensions (i.e., length and width) across multiple regions simultaneously. Tongue deformations are generally larger during chewing cycles compared to drinking cycles. Chewing and drinking also differ in the timing, relative to the gape cycle, of regional length and width, but not total length, deformations. This demonstrates functional differences in the temporal dynamics of localized shape changes, whereas the global properties of jaw-tongue coordination are maintained. Finally, differences in the trade-off between length and width deformations demonstrate that the properties of a muscular hydrostat are observed at the whole tongue level, but biomechanical variation (e.g., changes in movements and deformations) at the regional level exists. This study provides new critical insights into the regional contributions to tongue deformations as a basis for future work on multidimensional shape changes in soft tissues.