The tongue possesses a complex muscular structure, and its motor functions are also intricate. Therefore, it would be beneficial to use a computational physiological model of the tongue to examine its vital functions in normal and pathological conditions. Thus far, the studies of tongue models have focused on symmetric movements for normal speech. For clinical purposes, it is necessary to develop a physiological model to deal with daily vital activities such as mastication and swallowing. To do so, we constructed a full 3D physiological model of the tongue based on MRI data from a normal subject, and verified the basic functions of the model based on anatomic and physiological knowledge. In this study, the model was applied to clinical issues: prediction and verification of the changes in movements of the tongue with a tumor before and after partial glossectomy, respectively. Tongue protrusion and lateral bending motion were examined for the prediction and verification. The simulation results were consistent with the observations for a patient with a tumor in the tongue. Comparisons of the simulation and observation in the clinical case showed that the model could predict potential effects of the glossectomy on the tongue movements. It is suggested that the model is a useful tool for pre-operative planning of glossectomy.