Figure 4. Movement of a grid of points on the tongue at four times in the respiratory cycle in one subject.

While Fig. 3 and part of Fig. 2A show the displacement of a single point tracked on the genioglossus, this analysis shows a grid of points tracked on the tongue. Panels A and B each show a triangular mesh superimposed on the tagged image in the mid-sagittal plane and lower axial plane, respectively. The vertical and horizontal distance between grid points is 5 mm (panel A) and 8 mm (panel B). In each panel, the region of the tongue with distinct respiratory movements is enlarged. In both panels, there is movement of the posterior region of genioglossus.