The Spinal Cord, Brain and Pain Transmission The dorsal (rear) root is the sensory root. The ventral (front) root is the motor root. The dorsal root ganglion contains cell bodies of general somatic afferent (inbound) neurons, mediates pain and temperature and synapse in the dorsal horn of the spinal cord. A-delta fibers are myelinated (insulated with a myelin sheath). The pain..