The paper presents a kinematical model enabling the analysis of mandibular motion in a sagittal plane. Based on the recorded trajectories of incisors, the configuration coordinates were identified. The configuration coordinates explicitly identify the position and orientation of the mandible during motion. Such values are basic to the evaluation of alteration in muscle length and to the orientation of forces in particular muscles. This paper also deals with the influence of the coefficients of the weight matrix on the character of the solutions of the configuration coordinates applied in the model study of the kinematical chain. The results of the numerical calculations obtained demonstrated that the trajectory representation was in a considerable concordance with the data recorded.