Figure 5.3: The three classes of neurons This illustration shows the positions in the nervous system of the three types of neurons. On the right is the central nervous system (more specifically, a cross section of the spinal cord), and on the left are muscles and skin. Motor neurons send messages from the central nervous system to muscles and glands. Sensory neurons send messages into the central nervous system from sensory organs, such as the skin. And interneurons, I ocated entirely within the central nervous system, carry messages between neurons.
Manfried Kage/Peter Arnold