Fig. 6. In vivo measurements of I1/I3 muscle dimensions in three consecutive swallows from a two-axis video recording of a transilluminated juvenile. All timebases have been normalized as in Fig. 1E-G. Each data point is the mean of a 0.2 s (normalized) interval. Values are means ± S.E.M. Intervals t1, t2, t3 and t4 are defined in Materials and methods. (A) Estimated I1/I3 muscle antero-posterior length computed as 45% of the total buccal mass antero-posterior length (Drushel et al., 1998). N=2-6 (mean=4.3). Lengths were measured in medio-lateral view. (B) Estimated I1/I3 muscle mediolateral width computed by dividing the dorso-ventral views of the I1/I3 muscle into six rings of equal antero-posterior thickness (see Fig. 4). N=4-27 (mean=20.8). Ring 1 (posteriormost) is at the lateral groove, and ring 6 (anteriormost) is at the opening of the jaws.