Now let's define what a nucleus is with respect to the nervous system. So the nucleus here doesn't actually refer to the individual nucleus inside the cell body of our neuronuron. So the nucleus refers to a collection of many neurons of many cell bodies found within the central nervous system. On the other hand, if we are examining a collection or a group of cell bodies a group of neurons inside the peripheral nervous system this is known as a ganglia. So ganglia are those cells inside our peripheral nervous system and nucleus refers to our groups of neurons inside the central nervous system. Now, what about the pre ganglionic neuron and the post ganglionic neurons?