The kinematics of the biting and chewing mouthparts of insects is a complex interaction of various components forming multiple jointed chains. The novel technique of in vivo cineradiography by means of Synchrotron radiation was used to elucidate the motion cycles in the cockroach Periplaneta americana. Digital X-ray footage sequences were used in order to calculate pre-defined angles and distances, each representing characteristic aspects of the movement pattern. We were able to analyze the interactions of the mouthpart components and to generate a functional model of maxillary movement by integrating kinematic results, morphological dissections, and fluorescence microscopy. During the opening and closing cycles that take 450-500 ms on average, we found strong correlations between the measured maxillary and mandibular angles, indicating a strong neural coordination of these movements, as manifested by strong antiphasic courses of the maxillae and the mandibles and antiphasic patterns of the rotation of the cardo about its basic articulation at the head and by the deflection between the cardo and stipes. In our functional model of the maxilla, its movement pattern is explained by the antagonistic activity of five adductor / promotor muscles and one adductor / remotor muscle. However, beyond the observed intersegmental and bilateral stereotypy, certain amounts of variation across subsequent cycles within a sequence were observed with respect to the degree of correlation between the various mouthparts and the maximum, minimum, and time course of the angular movements. Although generally correlated with the movement pattern of the mandibles and the maxillary cardo-stipes complex, such plastic behavior was especially observed in the maxillary palpi and the labium.