Dorsal column pathway of visceral pain transmission. Adapted from Nauta HJ, et al. Surgical interruption of a midline dorsal column visceral pain pathway. J Neurosurg, 86:538–542, 1997. The dorsal column pathway is composed of branches of primary afferent fibers, some of which project directly to the dorsal column nuclei, and of the axons of postsynaptic dorsal column neurons. Pelvic viscera nociceptive input activates the postsynaptic dorsal column neurons of the spinal cord and is relayed to higher centers. PSDC neurons receiving pelvic visceral input send their axons in the midline of the dorsal column to synapse in the nucleus gracilis. Then, the pathway crosses the midline in the lower brainstem to ascend to the ventral posterolateral nucleus of the thalamus. PSDC (postsynaptic dorsal column); VPL (ventral posterolateral), DRG (dorsal root ganglion).