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تسجيل

Ventrolateral Spinothalamic Tract

المؤلف:  Kim E. Barrett, Susan M. Barman, Heddwen L. Brooks, Jason X.-J. Yuan

المصدر:  Ganongs Review of Medical Physiology

الجزء والصفحة:  25th E, P170-171

2026-10-12

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Fibers from nociceptors and thermoreceptors synapse on neurons in the dorsal horn of the spinal cord. The axons from these dorsal horn neurons cross the midline and ascend in the ventrolateral quadrant of the spinal cord, where they form the ventrolateral spinothalamic pathway (Figure1). Fibers within this tract synapse in the VPL. Some dorsal horn neurons that receive nociceptive input synapse in the reticular formation of the brainstem (spinoreticular pathway) and then project to the centrolateral nucleus of the thalamus.

Fig1. Ascending tracts carrying sensory information from peripheral receptors to the cerebral cortex. A) Dorsal column pathway mediates touch, vibratory sense, and proprioception. Sensory fibers ascend ipsilaterally via the spinal dorsal columns to medullary gracilus and cuneate nuclei; from there the fibers cross the midline and ascend in the medial lemniscus to the contralateral thalamic ventral posterior lateral (VPL) and then to the primary somatosensory cortex. B) Ventrolateral spinothalamic tract mediates pain and temperature. These sensory fibers terminate in the dorsal horn and projections from there cross the midline and ascend in the ventrolateral quadrant of the spinal cord to the VPL and then to the primary somatosensory cortex.

Positron emission tomographic (PET) and functional magnetic resonance imaging (fMRI) studies in healthy humans indicate that pain activates the primary and secondary somatosensory cortex and the cingulate gyrus on the side opposite the stimulus. In addition, the amygdala, frontal lobe, and the insular cortex are activated. These technologies were important in distinguishing two components of pain path ways. Researchers found that noxious stimuli that did not induce a change in affect caused an increased metabolism in the primary somatosensory cortex, whereas stimuli that elicited motivational-affective responses activated a larger portion of the cortex. This showed that the pathway to the primary somatosensory cortex is responsible for the discriminative aspect of pain. In contrast, the pathway that includes syn apses in the brainstem reticular formation and centrolateral thalamic nucleus projects to the frontal lobe, limbic system, and insular cortex. This pathway mediates the motivational affective component of pain.

Visceral sensation travels along the same central pathways as somatic sensation in the spinothalamic tracts and thalamic radiations, and the cortical receiving areas for visceral sensation are intermixed with the somatic receiving areas.