Fig. 1.

Development of finite element (FE) mesh from images of human lingual myofiber tracts obtained by diffusion tensor MRI with tractography. A: anatomy of the muscles present in the midsagittal plane of the tongue, shown in schematic view displaying several principal muscle groups and their bony attachments. Distinguished muscle groups include genioglossus (gg), verticalis (v), geniohyoid (gh), superior longitudinalis (sl), and inferior longitudinalis (il), with connections shown to the symphysis and the hyoid bones. B: diffusion tensor imaging (DTI) tractography images of myofiber tracts noted in A. For these imaging experiments, diffusion-weighted gradients were applied in 90 directions, employing single-shot echo-planar spatial encoding with repetition time = 3,000 ms, echo time = 80 ms, field of view 192 mm × 192 mm, slice thickness 3 mm, and b-value of 500 s/mm², followed by the streamline construction of multivoxel myofiber tracts along the maximum diffusion vector per voxel. C: DTI tractography myofiber tracts displayed along with the points of insertion into midsagittal and non-midsagittal structures: geniohyoid (gh), hyoglossus (hg), styloglossus (sg), and inferior longitudinalis (il). D: FE mesh whose elemental alignment is derived from the principal diffusion direction per voxel obtained through DTI, including midsagittal and out-of-plane muscles, as well as boundary conditions such as attachments to the symphysis and hyoid bones. Note specifically that the hyoid bone is attached to fixed structures via elastic (connective tissue) structures.