Spinoreticular tract

The spinoreticular tract (also paleospinothalamic pathway, or indirect pathway of the anterolateral system) is a partially decussating (crossed-over) four-neuron sensory pathway of the central nervous system. The tract transmits slow nociceptive/pain information (but thermal, and crude touch information as well) from the spinal cord to reticular formation which in turn relays the information to the thalamus via reticulothalamic fibers as well as to other parts of the brain (as opposed to the spinothalamic tract - the direct pathway of the anterolateral system - which projects from the spinal cord to the thalamus directly without such "layovers"). Most (85%) second-order axons arising from sensory C first-order fibers ascend in the spinoreticular tract - it is consequently responsible for transmitting "slow", dull, poorly-localised pain. By projecting to the reticular activating system (RAS), the tract also mediates arousal/alertness (including wakefulness) in response to noxious (harmful) stimuli. The tract is phylogenetically older than the spinothalamic ("neospinothalamic") tract.^{[1][page needed]}