Human Perspiration and Cutaneous Circulation
Flavia Meyer, Zbigniew Szygula, Boguslaw Wilk in Fluid Balance, Hydration, and Athletic Performance, 2016
The thermoregulatory center is located within the pre-optic hypothalamic regions of the brain, integrating thermal information detected in the central nervous system coupled with information transmitted from thermoreceptors of the skin and core (Aronsohn and Sachs 1885; Kahn 1904; Moorhouse 1911; Ott 1877). The identification of neural pathways responsible for sweating or cutaneous active vasodilation in humans is difficult and as such the exact neurological pathways are not entirely understood. Based on evidence from both animal studies and human anatomical data (Kuno 1956; Low 2004; Nakamura et al. 2004; Sato et al. 1989), the neural pathway from the brain to thermoregulatory organs is thought to be the following: efferent signals from the pre-optic area in the hypothalamus travel via the tegmentum of the pons and the medullary raphe regions to the intermediolateral cell column of the spinal cord. In the spinal cord, neurons emerge from the ventral horn, pass through the white ramus communicans, and then synapse in the sympathetic ganglia. Postganglionic non-myelinated C-fibers (i.e., skin sympathetic nerves) pass through the gray ramus communicans, combine with peripheral nerves, and travel to sweat glands and cutaneous vessels, with these nerve fibers entwined around the periglandular tissue of the target organs (Uno 1977).
Basic Thermal Physiology: What Processes Lead to the Temperature Distribution on the Skin Surface
Kurt Ammer, Francis Ring in The Thermal Human Body, 2019
In humans, the neural pathway from the brain to sweat gland is thought to be as follows; efferent signals from the pre-optic hypothalamus travel via the tegmentum of the pons and the medullary raphe regions to the intermediolateral cell column of the spinal cord. In the spinal cord, neurons emerge from the ventral horn, pass through the white ramus communicans and then synapse in the sympathetic ganglia. Postganglionic non-myelinated C-fibres pass through the grey ramus communicans, combine with peripheral nerves and travel to sweat glands [12].
The Spinal Cord and the Spinal Canal
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand in Pediatric Regional Anesthesia, 2019
Rami communicantes are bundles of bidirectional fibers which connect the ventral ramus of each spinal nerve to the sympathetic chain (Figure 1.38). They convey (1) efferent (myelinated) preganglionic fibers to the sympathetic chain (white ramus communicans), (2) efferent (unmyelinated) postganglionic fibers (gray ramus communicans) that reenter the ventral primary ramus and migrate with its (efferent) fibers, and (3) afferent fibers from viscera to spinal ganglia (white ramus communicans).
Selective block of grey communicantes in upper thoracic sympathectomy. A feasibility study on human cadaveric specimens
Published in British Journal of Neurosurgery, 2020
Vicente Vanaclocha, Nieves Sáiz Sapena, Marlon Rivera, Juan Manuel Herrera, José María Ortiz-Criado, Ana Monzó-Blasco, Ricardo Guijarro-Jorge, Leyre Vanaclocha
The parietal pleura was incised perpendicular to the ribs and 1cm lateral to the sympathetic chain. The grey rami communicantes could be found running between the intercostal nerve and their corresponding sympathetic ganglia. The intercostal veins crossed the sympathetic chain in 63.33% (19/30) of the sides, 12/19 of them being on the right side. These intercostal veins could be dissected free and coagulated with harmonic scissors. No clips were used to clip the veins to prevent them from impeding further surgical manoeuvres. Each level had at least one grey ramus communicans (Figure 4), occasionally two (Figure 5). In all of the dissected chains, all the levels had one grey and one white ramus communicans, shaped as described previously. The incidence of ascending grey rami communicantes was 30% (9/30) and that of the descending ones was 16.66% (5/30). Two grey rami communicantes could be seen at T2 in 26.66% (8/30 sides). One of the rami communicantes connected with the same level sympathetic ganglion, and the other with the ganglion above (five cases, 16.66%) or below (two cases, 6.66%), and in one case it connected both above and below (3.33%). At T3 two grey rami communicantes could be seen in 13.33% (4/30 sides). One of the ramus communicans connected with the same level sympathetic ganglion and the other with the ganglion above (3 cases, 10%) or below (1 side, 3.33%). At T4 two grey rami communicantes could be seen in three of the sides (10%); two were ascending (6.66%) and one descending (3.33%) (Tables 1 and 2). We did not dissect any lower than T4 because this it is not done in real life surgery. The number of accessory rami communicantes was higher at T2 than at lower levels. The number of cases was insufficient to draw any statistical conclusions about which side had more accessory grey rami communicantes. The diameter of the grey rami communicantes was 0.87 ± 0.76 SD.
Related Knowledge Centers
- Dorsal Root Ganglion
- Lumbar Nerves
- Synapse
- Sympathetic Nervous System
- Myelin
- Sympathetic Ganglia
- Gray Ramus Communicans
- Preganglionic Nerve Fibers
- General Visceral Efferent Fibers
- General Visceral Afferent Fiber