Figure 2

Jaw and hyolingual kinematics during tongue base retraction (TBR) phase of swallow gape cycles. Traces are mean values +/− 1 SD. Gape angles are unadjusted means; all other variables are changes (δ) relative to the value at start of TBR. TBR was defined as the time during the swallow cycle starting when the posterior superficial tongue marker started moving posteriorly relative to the cranium until the time when the vallecular marker stopped moving posteriorly. All data are in the coordinate system of the cranium. (a) Jaw gape angle (in degrees). Y axis for animal J covers the full range of jaw gape angles. Y axes for animals K, C, H maximize resolution during TBR. A pitch angle of 0° or less indicates that the mandibular cusps are superior to the cranial cusps, i.e., intercuspation. (b) Change (δ) in X position (anteroposterior) of posterior superficial (P. surf.) and vallecular tongue markers in the tongue base. (c) Change (δ) in volume of oral cavity (OC), posterior oral tongue volume (POT), and tongue base volume (TB). Oral volume was modeled using an alpha hull with alpha = 6; tongue volume was modeled using meshes. (d) Change (δ) in TB dimensions, width, length, depth (mm). E. Change (δ) in tongue extrinsic tongue muscle lengths: styloglossus, hyoglossus, palatoglossus (mm). F. Change (δ) in hyoid X (anteroposterior) and Y (superoinferior) position. Data for Monkey J are given for the whole swallow cycle. Data for Monkeys K, C and H are given for the period from TBR onset (0.0 s) to 0.1 s. TBR phase is indicated by the pale yellow rectangles. Dashed line at offset of TBR in Monkey H indicates no vallecular marker data were available. TBR offset estimated as end of posterior superficial marker posterior movement.