It is my understanding that motor neurons transmit messages to the myocytes of skeletal muscles all over the body. This should make them part of the peripheral nervous system that transmits both the voluntary and involuntary movement of muscles. Now, I came across this site that says motor neurons are part of the Central Nervous system. https://qbi.uq.edu.au/brain/brain-anatomy/types-neurons. Which is right? My book specifying the peripheral information, or the website?
The peripheral nervous system refers to parts of the nervous system outside the brain and spinal cord. It includes the cranial nerves, spinal nerves and their roots and branches, peripheral nerves, and neuromuscular junctions. The anterior horn cells, although technically part of the central nervous system (CNS), are sometimes discussed with the peripheral nervous system because they are part of the motor unit.
It appears that even though the motor neurone body lies inside the CNS, the spinal nerves are by definition part of the PNS. Clearly some authors don't follow the convention hence the conflicting views.