Mammalian Feeding Motor Patterns1

Abstract

Both the anatomy and function of the mammalian masticatory system have attracted substantial interest. This review will discuss the general mammalian feeding patterns. An overview will be given of the evolutionary development and ontogeny of these patterns, the influence of occlusal forces, and recent developments in computer modeling. In mammals, basic symmetrical food transport cycles have been described for lapping and soft food ingestion. To increase chewing efficiency, a unilateral occlusal motion has been evolved replacing the slow closing phase in the basic cycle. The relative uniformity of the mammalian jaw-closer motor patterns during this chewing behavior, as characterized by electromyography (EMG), is striking. Nevertheless, several adaptations, clearly different from the primitive mammalian asymmetric masticatory motor pattern, can be distinguished. In contrast to the relative uniformity in motor patterns, the anatomical diversity of jaw systems is impressive and probably reflects the adaptation to diet. Detailed studies on the influence of occlusal force have been performed in the last decade. Data suggest that the masticatory cycles are largely shaped by sensory feedback. Also, the suckling food intake preceding mastication has been a point of interest. The suckling motor pattern resembles that of mastication, suggesting that the transition could be gradual during postnatal development. Recently, dynamic computer 3D-modeling has emerged as an analytical tool. The approach has the potential to help explain how structure and function interact.