Neurons are the primary type of cell that most anyone associates with the nervous system. Nervous tissue, present in both the CNS and PNS, contains two basic types of cells: neurons and glial cells. The equivalent structures in the CNS are not obvious from this overall perspective and are best examined in prepared tissue under the microscope. The structures of the PNS are referred to as ganglia and nerves, which can be seen as distinct structures. Figure 8.1 Central and Peripheral Nervous System. Depending on different aspects of the nervous system, the dividing line between central and peripheral is not necessarily universal. The peripheral nervous system is so named because it is on the periphery-meaning beyond the brain and spinal cord. In actuality, there are some elements of the peripheral nervous system that are within the cranial or vertebral cavities. It is a bit of an oversimplification to say that the CNS is what is inside these two cavities and the peripheral nervous system is outside of them, but that is one way to start to think about it. The brain is contained within the cranial cavity of the skull, and the spinal cord is contained within the vertebral cavity of the vertebral column. The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is everything else (see Figure 8.1). Anatomy (Structures) of the Nervous System The Central and Peripheral Nervous Systems The nervous system can be divided into two major regions: the central and peripheral nervous systems.
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