Dual Pathways for Transmission of Pain Signals into the Central Nervous System Even though all pain receptors are free nerve
endings, these endings use two separate pathways for transmittingpain signals into the central nervous
system. The two pathways mainly correspond to the two types of pain—a fastsharp pain pathway and
a slow-chronic pain pathway. Peripheral Pain Fibers —―Fast‖ and ―Slow‖ Fibers. The fast-sharp pain signals are elicited by either mechanical or thermal pain stimuli; they are
transmitte in theperipheral nerves to the spinal cord by small type A
fibers at velocities between 6
and 30 m/sec. Conversely,the slow-chronic type of pain is elicited mostly by chemicaltypes of pain
stimuli but sometimes by persisting mechanical or thermal stimuli.
