The splanchnic nerves are a group of nerves that originate from the sympathetic nervous system and innervate the viscera (internal organs) of the body. These nerves are classified based on the region they innervate: the thoracic splanchnic nerves innervate the thoracic viscera (such as the heart and lungs), while the abdominal splanchnic nerves innervate the abdominal viscera (such as the stomach, intestines, liver, and kidneys).
The abdominal splanchnic nerves typically terminate in the prevertebral ganglia, which are located anterior to the vertebral column in the abdomen. These ganglia include the celiac ganglion, the superior mesenteric ganglion, and the inferior mesenteric ganglion. The preganglionic fibers from the splanchnic nerves synapse with the postganglionic fibers in these ganglia, which then innervate the target organs.
It is important to note that the exact termination points of the splanchnic nerves can vary depending on the individual and the specific anatomy of the nervous system.