Poliomyelitis is caused by a virus that spreads easily in human populations. most people with polio infections show no symptoms of disease. however, in a small percentage of victims, the virus enters the central nervous system and attacks the motor neurons of the spinal cord. motor neurons are an example of what type or class of neuron? a bipolar neuron that has two processes separated by the cell bodya multipolar neuron that has two or more dendrites and a single axonan anaxonic neuron that has processes that are all dendritesa unipolar neuron that has a single elongated process, with the cell body located off to the side