The two main divisions of the nervous system are the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which includes all the nerves outside of the CNS.
The main function of oligodendrocytes in the CNS is to produce myelin, which allows the signal to jump speeding up the process of neural transmission.
The meninges are made of connective tissue.
The Schwann cells wrap around the axons in the peripheral nervous system and create a myelin sheath that allows for faster signal transmission.