The first-order nociceptive neurons from the head, face and intraoral structures have somata in the trigeminal ganglion (Figure 7.2). The VPL sends axons to the primary somatosensory cortex (SCI). The VPL is thought to mainly be concerned with discriminatory functions. Most of the pain fibers from the lower extremity and the body below the neck terminate in the ventroposterolateral (VPL) nucleus and ventroposteroinferior (VPI) nucleus of the thalamus, which serves as a relay station that sends the signals to the primary cortex. Axons from layer I neurons decussate in the anterior white commissure, at approximately the same level they enter the cord, and ascend in the contralateral anterolateral quadrant. The first-order nociceptive neurons (in the DRG) make synaptic connections in Rexed layer I neurons (marginal zone). The neospinothalamic tract has few synapses and constitutes the classical lateral spinothalamic tract (LST) (Figure 7.1). Each pain tract originates in different spinal cord regions and ascends to terminate in different areas in the CNS. The first-order neurons are located in the dorsal root ganglion (DRG) for all three pathways. The ascending pathways that mediate pain consist of three different tracts: the neospinothalamic tract, the paleospinothalamic tract and the archispinothalamic tract. Pain travels through “redundant” pathways, ensuring to inform the subject to "Get out of this situation immediately." ![]() Given the importance of pain sensation, it is not surprising that the central and peripheral neuronal pathways that subserve the transmission of nociceptive information and the pathway that transmits and modulates this somatosensory transmission are essential to understanding this somatosensory modality. Without these attributes, the organism has no means to prevent or minimize tissue injury. ![]() Sensitivity and reactivity to noxious stimuli are essential to the well-being and survival of an organism.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |