Some Divisions, in descending order/organization:

THE NERVOUS SYSTEM

I.Central Nervous System(CNS)

A.Brain

B.Spinal Cord

II.Peripheral Nervous System(PNS)

A.Sensory PathWays

B.Motor PathWays

1.Somatic

2.Autonomic

a.Sympathetic (excitatory)

b.ParaSympathetic (inhibitory)

...(a work in progress ;-)