The three-dimensional architecture of the human styloglossus especially its posterior muscle bundles.

The arrangement of the lingual muscles in the interior of the human tongue, particularly the course of the posterior muscle bundles of the styloglossus, was studied by gross anatomical examination and SEM, and its relationship with tongue functions was considered. The styloglossus divided into anterior and posterior fiber bundles. The bilateral anterior fiber bundles ran anteriorly, and fused at the median region of the lower surface of the tongue, forming a large arched structure. The posterior bundles divided into 10 or more smaller bundles and entered the interior of the tongue. These muscle bundles passed through the spaces between the inferior longitudinal and genioglossus and inserted in the lingual septum, forming a small arched structure. These posterior muscle bundles passed near the midpoint between the central third and dorsal third of the line between the mental spine and the dorsal surface of the tongue in the upper half of the root of the tongue, showing a multilayer structure. In many of the areas in which posterior muscle bundles were distributed, muscle bundles in the tongue were arranged along the posterior muscle bundles of the styloglossus, glossopharyngeal bundles of the superior pharyngeal constrictor muscle, and transverse muscle of the tongue from the deep layer to the dorsal surface of the tongue.