ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
The major ascending pathway for the senses of TOUCH and proprioception (see PROPRIOCEPTORS) for all parts of the body except the head. Primary sensory afferents from touch receptors and proprioceptors enter the spinal cord and ascend in the dorsal columns. Afferents from the feet and legs are medial to those from the hands and arms and synapse in the GRACILE NUCLEUS and CUNEATE NUCLEUS, respectively. These two nuclei are called the dorsal column nuclei. Axons from the second-order neurons in these nuclei cross to the opposite side of the BRAINSTEM and ascend to the THALAMUS in a fibre tract called the MEDIAL LEMNISCUS. Fibres in the medial lemniscus are joined by second-order axons from the trigeminal nuclei which carry similar information for the face and head. Damage to the neurons in the dorsal column- medial lemniscal system produces deficits in fine touch and proprioception.
The Physiology of Pain
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand in Pediatric Regional Anesthesia, 2019
The connections of afferent fibers with the interneurons and tracts of the spinal cord have been established from anatomical and electrophysiological studies, which have ascertained the spinal location of ascending nociceptive information. The spinocervical tract (from the spinal cord to the lateral cervical nucleus) and dorsal columns (from the spinal cord to ipsilateral dorsal column nuclei) would probably play an important role in the transmission of pain to supraspinal areas. In their review, Dennis and Melzack19 reported at least six ascending spinal pathways involved in the transmission of pain to the brain. These studies, however, remain incomplete and cannot explain the return of sensitivity to painful stimuli about 2 to 3 months after anterolateral spinal cordotomy. Some other tracts would probably be able to convey the relevant information after the usual paths have been destroyed.
Evidence for the Presence of a Visceral Pain Pathway in the Dorsal Column of the Spinal Cord
Mark J Rowe, Yoshiaki Iwamura in Somatosensory Processing: From Single Neuron to Brain Imaging, 2001
Anatomical studies in rats were initiated to establish which neurons in the spinal cord were the origins of the fibers traveling in the dorsal column that might be mediating the transmission of the visceral pain. The retrograde tracer, WGA-HRP, was injected into the dorsal column at the upper cervical spinal cord (Hirshberg et al., 1996). The retrograde tracer was absorbed into the axons and transported to cell bodies located in the central region throughout the length of the spinal cord and in particular at the level innervating the pelvic viscera (Fig. 4.2). The central region of the spinal cord is known to be involved in the processing of visceral information (Honda, 1985; Ness and Gebhart, 1987). The fiber projections of the cells located in central region of the L6-S1 spinal cord were then traced using an anterograde tracer (Hirshberg et al., 1996; Wang et al., 1996, 1999). Their fiber projections were followed throughout the length of the spinal cord to the gracile nucleus (Fig. 4.14). Thus, a direct anatomical projection was established arising from spinal visceral processing regions, traveling in the dorsal column and terminating in the dorsal column nuclei. This observation established the availability of a neuronal pathway in the dorsal column that could relay visceral information from neurons in the central region of the sacral spinal cord where visceral information is pro-cessed. Another component of the postsynaptic dorsal column pathway previously described has its cells of origin primarily in lamina III and IV (Bennett et al., 1983) and is believed not to carry information about pain in rats (Giesler and Cliffer, 1984). However, this view was based on the lack of responses of these neurons to cutaneous noxious heat stimuli. The neurons did respond to strong mechanical stimulation of the skin.
A population-based case–control study of the association between cervical spondylosis and tinnitus
Published in International Journal of Audiology, 2021
Yen-Fu Cheng, Sudha Xirasagar, Tzong-Hann Yang, Chuan-Song Wu, Nai-Wen Kuo, Herng-Ching Lin
The mechanism underlying the association is likely to be related to somatosensory pathway disruptions in cervical spondylosis. Although damage to the peripheral auditory system accounts for majority of tinnitus cases, our study affirms the potential for tinnitus to be evoked by disturbed inputs via the somatosensory pathways. Extensive studies with animal models have shown that neural stimuli originating in the auditory and somatosensory systems are integrated in the cochlea nucleus of the brainstem (CN) (Brozoski and Bauer 2005; Koehler and Shore 2013; Roberts et al. 2010; Zhang et al. 2019). In addition to the ascending auditory pathway from the auditory nerves and descending auditory pathways from the auditory centres in the midbrain and auditory cortex, the somatosensory projection of dorsal column nuclei, trigeminal and cervical ganglia also converge at this site. As a result, dysregulated synchrony across this neural ensemble along the auditory and related somatosensory pathway that converge in the cochlea nucleus can cause tinnitus-generating neural discharges, even in the absence of a permanent shift in the hearing threshold (Koehler and Shore 2013).
Related Knowledge Centers
- Brainstem
- Neuroanatomy
- Nucleus
- Proprioception
- Somatosensory System
- Medulla Oblongata
- Brain
- Thalamus
- Dorsal Column–Medial Lemniscus Pathway
- Neuron