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The Spinal Cord and the Spinal Canal
Published in Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand, Pediatric Regional Anesthesia, 2019
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand
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).
Basic Thermal Physiology: What Processes Lead to the Temperature Distribution on the Skin Surface
Published in Kurt Ammer, Francis Ring, 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].
Back and central nervous system
Published in Aida Lai, Essential Concepts in Anatomy and Pathology for Undergraduate Revision, 2018
White ramus communicans (WRC)– connects spinal nerve to sympathetic ganglion– carries preganglionic fibres
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.