- Sharp, brief, well-localized pain is conveyed into the spinal cord by A delta fibers.(see Blum. Table 7.2)
- These fiber come into the dorsal root entry zone rather laterally and may pass up or down the cord for several segments in Lissaur's Tract before turning deeply to terminate upon second order neurons in laminae I and V.
- The second order neurons give rise to axons which cross the midline, as shown, in the Anterior White Commissure.
- These ascending axons then join the ascending anterolateral pathway on its deep surface, imparting a somatotopic organization to the pathway, as shown below.
- The fibers ascend through the tegmentum of the brainstem to terminate in the VPL and intralaminar nuclei of the thalamus.