Review Questions Chapter 7 Answer Key From Textbook 1. Are the dorsal root ganglia in the central or peripheral nervous system? The somatic sensory neurons collect information from the skin, muscles and joints, and enter the spinal cord through the dorsal roots. The cell bodies of these neurons lie outside the spinal cord, in clusters called dorsal root ganglia. The dorsal root ganglia are in the peripheral nervous system because they are outside the spinal cord. Furthermore, they are derived from the neural crest cells during embryonic development, as are all parts of the peripheral nervous system. Neurons of the central nervous system are derived from the neural tube 2. Is the myelin sheath of optic nerve axons provided by Schwann cells or oligodendroglia? Why? The retina and optic nerve are part of the central nervous system as they are derived from the neural tube. We know that the oligodendroglia provide myelin for the central nervous system and Schwann cells provide myelin for the peripheral nervous system. Therefore, oligodendroglial cells must provide the myelin for the optic nerve.
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