Point 2 Intro Pathway Deficits Summary Problems Contents Anatomy

The central processes of delta and C fibers in the lateral division of the dorsal root do something quite different than the alpha-betas. These axons enter a zone at the top of the dorsal horn called the zone of Lissauer (ZL) and then course ROSTRALLY for approximately 2 spinal segments within this zone before they dive into the dorsal horn, where they synapse. THERE HAS BEEN NO CROSSING YET!!!!! Cells in the DORSAL HORN that receive this pain and temperature information then send axons which CROSS and enter the anterolateral portion of the lateral funiculus, where they ascend to the thalamus (the great gateway to the cortex). In particular, they terminate in the ventral posterolateral nucleus (VPL). The VPL then relays the information to the somatosensory cortex (Areas 3, 1, and 2). Information carried over the pain, temperature and crude touch pathway begins in the processes of dorsal root ganglion cells, but the ANTEROLATERAL SYSTEM ( [ALS] axons in the anterolateral part of the white matter) TAKES ORIGIN FROM CELLS IN THE CONTRALATERAL DORSAL HORN. THIS SYSTEM IS ALSO CALLED THE SPINOTHALAMIC PATHWAY (ORIGIN IN SPINAL CORD, TERMINATION IN THALAMUS). As the fibers enter the ALS to ascend they are organized such that the most caudal fibers (sacral-coccygeal) lie laterally within the ALS. Compare this with the dorsal column system!!!