Related Experiment Video
Updated: Jun 29, 2026

The Vermicelli and Capellini Handling Tests: Simple quantitative measures of dexterous forepaw function in rats and mice
Published on: July 21, 2010
The Kinematics of Proal Chewing in Rats
E D McParland1,2, J K Mitchell1, J D Laurence-Chasen3,4
1Department of Biology, Knox College, Galesburg, IL 61401, USA.
Abstract:
Chewing kinematics are well-documented in several mammal species with fused mandibular symphyses, but relatively understudied in mammals with an unfused symphysis, despite the fact that more than half of extant Mammalia have an unfused mandibular symphysis. The Wistar brown rat (Rattus norvegicus) is widely used in human health research, including studies of mastication or neurological studies where mastication is the output behavior. These animals are known to have unfused mandibular symphyses and proal jaw (rostrocaudal) motion during occlusion, but the lack of high resolution, 3-dimensional analysis of rat chewing leaves the functional significance of symphyseal mobility unknown. We used biplanar fluoroscopy and the X-ray reconstruction of moving morphology workflow to quantify chewing kinematics in 3 brown rats, quantifying overall jaw kinematics, including motions about the temporomandibular joint and unfused mandibular symphysis. During occlusion, the teeth and the mandibular condyle translate almost exclusively anteriorly (proal) during occlusion, with little motion in any other degrees of freedom. At the symphysis, we observed minimal flexion throughout the chew cycle. Overall, there are fundamental differences in jaw kinematics between rats and other mammals and therefore rats are not an appropriate proxy for ancestral mammal jaw mechanics. Additionally, differences between humans and rat chewing kinematics must be considered when using rats as a clinical model for pathological feeding research.
Related Concept Videos
Mechanical Protein Functions
Force
The study of motion is called kinematics, but kinematics only describes the way...
Power Expended by a Constant Force
Non-conservative Forces
Also unlike their conservative counterparts, they are path-dependent; where the object starts and stops does matter. For example, a grinding wheel applies a...
Simplification of a Force and Couple System: II
Conservative Forces
Conservative forces are forces that are dependent only on the initial and final positions of an object and that are independent of the path that the object takes between these positions. These forces conserve energy, which means that the work done by the force is independent of the path...

