Ohio University, Department of Biological Sciences, Irvine Hall 107, Athens, OH 45701, USA.
Ohio University Heritage College of Osteopathic Medicine, Department of Biomedical Sciences, 4180 Warrensville Center Road, SPS121, Warrensville Heights, OH 44122, USA.
J Exp Biol. 2021 Apr 1;224(7). doi: 10.1242/jeb.239509. Epub 2021 Apr 15.
Mastication and drinking are rhythmic and cyclic oral behaviors that require interactions between the tongue, jaw and a food or liquid bolus, respectively. During mastication, the tongue transports and positions the bolus for breakdown between the teeth. During drinking, the tongue aids in ingestion and then transports the bolus to the oropharynx. The objective of this study was to compare jaw and tongue kinematics during chewing and drinking in pigs. We hypothesized there would be differences in jaw gape cycle dynamics and tongue protraction-retraction between behaviors. Mastication cycles had an extended slow-close phase, reflecting tooth-food-tooth contact, whereas drinking cycles had an extended slow-open phase, corresponding to tongue protrusion into the liquid. Compared with chewing, drinking jaw movements were of lower magnitude for all degrees of freedom examined (jaw protraction, yaw and pitch), and were bilaterally symmetrical with virtually no yaw. The magnitude of tongue protraction-retraction (Txt), relative to a mandibular coordinate system, was greater during mastication than during drinking, but there were minimal differences in the timing of maximum and minimum Txt relative to the jaw gape cycle between behaviors. However, during drinking, the tongue tip is often located outside the oral cavity for the entire cycle, leading to differences between behaviors in the timing of anterior marker maximum Txt. This demonstrates that there is variation in tongue-jaw coordination between behaviors. These results show that jaw and tongue movements vary significantly between mastication and drinking, which hints at differences in the central control of these behaviors.
咀嚼和饮水是有节奏的、周期性的口腔行为，分别需要舌、颌和食物或液体团块之间的相互作用。在咀嚼过程中，舌将食物团块运送到牙齿之间进行分解。在饮水过程中，舌帮助摄取食物团块，然后将其运送到口咽。本研究的目的是比较猪在咀嚼和饮水时的颌骨和舌运动。我们假设在行为之间会存在颌口距循环动力学和舌伸出-缩回的差异。咀嚼周期有一个延长的慢速闭合阶段，反映了牙齿-食物-牙齿的接触，而饮水周期有一个延长的慢速打开阶段，与舌伸进液体相对应。与咀嚼相比，在所有检查的自由度上（颌骨前伸、偏航和俯仰），饮水时的颌骨运动幅度较小，并且是双侧对称的，几乎没有偏航。相对于下颌骨坐标系，舌伸出-缩回的幅度（Txt）在咀嚼时大于饮水时，但在行为之间，相对于颌口距周期，最大和最小 Txt 的时间差异最小。然而，在饮水时，舌尖通常在整个周期内都位于口腔外，导致行为之间的前标记最大 Txt 时间存在差异。这表明在行为之间存在舌-颌协调的变化。这些结果表明，咀嚼和饮水时颌骨和舌的运动有显著差异，这暗示了这些行为的中枢控制存在差异。
