spinoreticular

The spinoreticular tract is an ascending nociceptive pathway that carries pain signals from the spinal cord to the brainstem reticular formation and onward to thalamic and cortical regions. It originates from neurons in the dorsal horn of the spinal cord, primarily in the laminae I and II, which receive input from peripheral C fibers and Aδ fibers. The axons cross within the spinal cord via the ventral white commissure and ascend in the anterolateral column to the brainstem. In the brainstem, these fibers terminate in reticular formation structures, including the medullary and pontine reticular formations, and project to the intralaminar nuclei of the thalamus.

From the thalamus, relays distribute diffusely to widespread cortical areas, supporting a broad, diffuse perception of pain and its arousal and affective components. The tract thus contributes to the nonlocalized, sustained aspects of pain and to the overall state of arousal and attention that accompanies nociceptive stimuli.

Functionally, the spinoreticular tract complements the better-localized pain signals carried by the spinothalamic tract by conveying the emotional, cognitive, and autonomic dimensions of pain. It plays a role in sustained attention to pain, autonomic responses, and the mood-related and arousal aspects of nociception rather than precise localization.

Clinical relevance centers on its involvement in the diffuse perception of pain and in pain modulation. Alterations in spinoreticular signaling can influence how pain is perceived during sustained nociception and in states characterized by heightened arousal or affective response to pain.