The Human Nervous System

Nervous System Divisions and Structures

  1. The central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord.
  2. The peripheral nervous system (PNS) is the part of the nervous system that consists of the nerves and ganglia outside of the brain and spinal cord.
  3. Schematic image showing the locations of a few tracts of the spinal cord.

  4. In the peripheral nervous system, an afferent nerve fiber is the axon of a sensory neuron, a long process carrying nerve impulses from sensory receptors or sense organs toward the central nervous system.
  5. A motor neuron is a nerve cell whose cell body is located in the spinal cord and whose fiber (axon) projects outside the spinal cord to directly or indirectly control effector organs, mainly muscles and glands.
  6. In the peripheral nervous system, an efferent nerve fiber is the axon of a motor neuron, a long process extending far from the nerve cell body carrying nerve impulses away from the central nervous system toward the effector organs.
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