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The sympathetic trunk is a fundamental part of the sympathetic nervous system, and part of the autonomic nervous system. It allows nerve fibres to travel to spinal nerves that are superior and inferior to the one in which they originated. Also, a number of nerves, such as most of the splanchnic nerves, arise directly from the trunks.
There are two kinds of neurons involved in the transmission of any signal through the sympathetic system: pre-ganglionic and post-ganglionic. The shorter preganglionic neurons originate in the thoracolumbar division of the spinal cord specifically at T1 to L2~L3, and travel to a ganglion, often one of the paravertebral ganglia, where they synapse with a postganglionic neuron.
Once they synapse in the sympathetic ganglion in the sympathetic trunk, they exit the trunk as gray rami to join the spinal nerve and innervate the appropriate structure. Even though the sympathetic trunk extends below L2, there are no more white rami communicantes below L2 because the intermediolateral cell column ends before this. The fibers ...
The sympathetic ganglia, or paravertebral ganglia, are autonomic ganglia of the sympathetic nervous system. Ganglia are 20,000 to 30,000 afferent and efferent nerve cell bodies that run along on either side of the spinal cord. Afferent nerve cell bodies bring information from the body to the brain and spinal cord, while efferent nerve cell ...
The upper two lumbar ganglia (L1 and L2) of the sympathetic chain also give rise to the lumbar splanchnic nerves. Splanchnic nerves are paired visceral nerves carrying preganglionic sympathetic and general visceral afferent fibers. The lumbar splanchnic nerves travel through the lumbar sympathetic ganglion but do not synapse there.
The thoracic portion of the sympathetic trunk typically has 12 thoracic ganglia. Emerging from the ganglia are thoracic splanchnic nerves (the cardiopulmonary, the greater, lesser, and least splanchnic nerves) that help provide sympathetic innervation to thoracic and abdominal structures. The thoracic part of sympathetic trunk lies posterior to ...
The grey and white rami communicantes are responsible for conveying autonomic signals, specifically for the sympathetic nervous system. Their difference in colouration is caused by differences in myelination of the nerve fibres contained within, i.e. there are more myelinated than unmyelinated fibres in the white rami communicantes while the ...
The sacral sympathetic nerves arise from the sacral part of the sympathetic trunk, emerging anteriorly from the ganglia.They travel to their corresponding side's inferior hypogastric plexus, where the preganglionic nerve fibers synapse with the postganglionic sympathetic neurons, whose fibers ascend to the superior hypogastric plexus, the aortic plexus and the inferior mesenteric plexus, where ...