Nerve and muscle: Basic concepts

Reflex and voluntary motor activity results from the integration of multiple and continuous stimuli. The hierarchical division of motor behavior reflects its particular goal. Thus, short interneuron arcs in the spinal cord mediate simple reflexes, and complex motor activities involve central processors, such as motor cortex, cerebellum, and basal ganglia. Regardless of complexity, motor activity always involves nerves and muscles as the final pathway for the production of force and movement. This chapter presents the basic aspects of neuromuscular biology: how neural signals initiate the contractile process, and how it is regulated.