Figure 1
From: Gene therapy for pain: Introduction to the special issue

Neuroanatomy of pain. Acute pain signals are transmitted by Aδ and C fibers to the spinal cord. In the dorsal horn of spinal cord the primary (dorsal root ganglia) afferent synapses with second-order neurons that project rostrally. Third-order neurons of the thalamus and brainstem nuclei project to sensory and limbic cortex.