The purpose of this study was to show the benefit of visualizing a tree-dimensional (3D) image of the tongue's muscle structure, which until now has been regarded as fully understood. Until now, no suitable 3D observation methods have been developed for soft tissue, such as the tongue, using histological magnification. For this purpose, this study used a micro-computed tomographic method (micro-CT) and image processing after the fixation, decalcification, and dehydration of a mouse tongue. Results: 3D rendered images of tongue muscles obtained by micro-CT showed every muscle and their relationships to each other. The superior longitudinal and the hyoglossus muscles of the tongue made up one group, while the inferior longitudinal and the styloglossus muscles of the tongue made up another. The boundary of the two muscles in each group was difficult to distinguish. On the other hand, what appear to be newly described muscles were identified. These results indicate that our micro-CT method is beneficial and that classical knowledge of tongue muscles derived from two-dimensional (2D) images does not fully describe the actual complexity of the tongue muscles. In our opinion, 3D rendered images mixed with raw structure can provide a more in-depth picture of the tongue from an integrated as well as an analytical perspective.

Background: The suitability of micro-computed tomography (CT) for soft tissue applications has been well documented. Although the application of micro-CT to the three dimensional (3D) structure of the tongue muscle has been reported, a 3D rendering and/or a schematic view of the tongue muscle has yet to be published. Material and Method: First, muse tongues were fixed and decalcified, and then the vertical muscle (Ve), the transverse muscle (Tr), and/or the genioglossus muscle of the mouse tongue (Ge) were analyzed using micro-CT and are shown in this report in rendered images and pattern diagrams. Results: 1) The Tr is classified into three parts: the first part extends from the middle to the apical part of the tongue; the second part is strongly connected to the superior longitudinal muscles of the tongue (Lo); the third part fans out from the middle to the root of the tongue. 2) The Ve is classified into two main groups: the first group joins the dorsal and the lateral parts of the tongue; the second group joins the dorsal part and the floor of the tongue. 3) Ge is classified into four parts: three parts comprise the Ge apical and middle parts of the tongue, with one part in the inferior longitudinal muscles of the tongue, one joining the lingual septum of the tongue (LS), and the other joining the sub-surface of the dorsal part of the Lo. The remaining Ge exits in a fan-like manner through the root of the tongue and then joins the Tr.