Pathway
C fibers synapse to second-order projection neurons in the spinal cord at the upper laminae of the dorsal horn in the substantia gelatinosa. The second-order projection neurons are of the wide dynamic range (WDR) type, which receive input from both nociceptive terminals as well as myelinated A-type fibers. There are three types of second order projection neurons in the spinothalamic tract: wide dynamic range (WDR), high threshold (HT), and low threshold (LT). These classifications are based on their responses to mechanical stimuli. The second-order neurons ascend to the brain stem and thalamus in the ventrolateral, or anterolateral, quadrant of the contralateral half of the spinal cord, forming the spinothalamic tract. The spinothalamic tract is the main pathway associated with pain and temperature perception, which immediately crosses the spinal cord laterally. This crossover feature is clinically important because it allows for identification of the location of injury.
Read more about this topic: Group C Nerve Fiber
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“And open field, through which the pathway wound,
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The morning rose, in memorable pomp,
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—William Wordsworth (1770–1850)
“Many are obstinate with regard to the pathway once they have set upon it, few with regard to the goal.”
—Friedrich Nietzsche (1844–1900)
“To learn from our enemies is the best pathway to loving them: for it makes us grateful to them.”
—Friedrich Nietzsche (1844–1900)