(Fig 56-1: Afferent pathways involved in nociceptive regulation and Fig 56-2: Efferent pathways involved in nociceptive regulation and Table 56-1: Primary Afferent Nerves). α-δ Fibers transmit “first pain,” which is described as sharp or stinging in nature and is well localized. Polymodal C fibers transmit “second pain,” which is more diffuse in nature and is associated with the affective and motivational aspects of pain.