Multiple Control Mechanisms Contribute to Functional Behaviors of the Head and Neck

Head stability is achieved through a convergence of reflex, voluntary, and biomechanical factors. Each of these mechanisms has distinct kinematic and dynamic characteristics that must be coordinated during production of normal movement patterns. An analysis of complex motor systems, such as the head and neck, should aid in revealing how the central nervous system combines and integrates these distinct control mechanisms. The frequency-related and spatial characteristics of each of these mechanisms suggest that command parameters during normal activity are not preprogrammed but dependent upon task constraints. The chapter discusses how the spatial organization of the neck muscles is altered to allow load changes during an isometric stabilization task.