Corpus: Greater splanchnic nerve

The greater splanchnic nerve is a nerve of the autonomic nervous system, originating from the thoracic part of the sympathetic trunk. It is classified as a visceral nerve (splanchnic nerve).

The greater splanchnic nerve contains sympathetic efferent and visceroafferent nerve fibers from the spinal cord segments Th5 to Th9, which pass through the thoracic ganglia without synapsing.

The greater splanchnic nerve runs parallel to the sympathetic trunk — on the right side alongside the azygos vein, and on the left side with the hemiazygos vein. It descends through the medial lumbar fissure of the diaphragm. Shortly after entering the abdominal cavity, the nerve reaches the celiac ganglion or the celiac plexus located around the coeliac trunk, where most fibers synapse with a second neuron. A thoracic splanchnic ganglion is often present along the course of the greater splanchnic nerve.

The greater splanchnic nerve provides preganglionic sympathetic fibers to the celiac ganglion and aorticorenal ganglia, and through these ganglia, it innervates much of the foregut. It also carries fibers to the adrenal medulla, where it controls the release of catecholamines.