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There are 12 pairs of cranial nerves. The cranial nerves are referred to by either name or Roman numeral (Fig 8–1 and Table 8–1). Some authorities contend that the olfactory peduncle (see Chapter 19) and the optic nerve (see Chapter 15) are not true nerves but rather fiber tracts of the brain, whereas nerve XI (the spinal accessory nerve) is derived, in part, from the upper cervical segments of the spinal cord. The remaining nine pairs relate to the brain stem.
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