Miscellaneous
Bobby Krishnachetty, Abdul Syed, Harriet Scott in Applied Anatomy for the FRCA, 2020
The ramus communicans is a communicating branch that connects two other nerves. With respect to the sympathetic nervous system, it is the branch that transmits signals between the spinal nerves and the sympathetic trunk. There are two types of rami communicantes – white and grey. The white rami communicantes appear white as they have more myelinated fibres than the grey. These only exist in the intermedio-lateral column, T1 to L2, and contain preganglionic fibres from the spinal cord to the paravertebral ganglia.The grey rami exist at every level throughout the spinal cord and contain postganglionic fibres, they connect from the sympathetic trunk to the spinal nerves.
Chapter Paper 1 Questions
James Day, Amy Thomson, Tamsin McAllister, Nawal Bahal in Get Through, 2014
Regarding the sympathetic nervous system:The sympathetic trunk runs bilaterally from the first thoracic vertebra to the second lumbar vertebraThe stellate ganglion is the name given to the fusion of the inferior cervical ganglion with the first thoracic ganglionCell bodies of the preganglionic neurones lie within the lateral horn of the spinal cordAll of the preganglionic neurones synapse within the sympathetic trunkThe preganglionic neurones synapse in the sympathetic trunk via the grey ramus communicans
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).
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
- Autonomic Nervous System
- Intermediolateral Nucleus
- Postganglionic Nerve Fibers
- Spinal Nerve
- Sympathetic Trunk
- White Ramus Communicans
- Sympathetic Nervous System
- Gray Ramus Communicans
- Preganglionic Nerve Fibers