‘Communication and control’ considers the human nervous system, which has two anatomically separate, but closely related, components: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is composed of two cerebral hemispheres, the brainstem and the spinal cord. The PNS is subdivided into the somatic and autonomic divisions. The somatic division includes the motor supply of the skeletal muscles and the sensory innervation of skin, muscles, and joints. This division of the peripheral nervous system mediates voluntary movement and much of perception. The autonomic system deals with activities that are primarily automatic such as the control of heart rate and blood pressure, which are involuntary.