Estimates of the kinematics of the medio-lateral widths of the I3 muscle during biting using the three-dimensional kinematic model. Estimates of the kinematics of the medio-lateral widths of the I3 muscle during biting using the three-dimensional kinematic model. A schematic medio-lateral view of the I1/I3/jaw complex is shown in Fig. 2C. (A-D) Widths of the continuous mesh representing the I3 muscle at six evenly spaced locations along its antero-posterior length for the first to fourth bites. The top trace in each panel (solid black line) is the medio-lateral width of the I3 muscle at the lateral groove. The bottom trace in each panel (broken line) is the medio-lateral width of the I3 muscle at the jaws. David M. Neustadter et al. J Exp Biol 2007;210:238-260 © The Company of Biologists Limited 2007