Lesser thoracic splanchnic nerve carries preganglionic sympathetic fibers from T10–T11 ganglia to the aorticorenal plexus.
The lesser thoracic splanchnic nerve is one of the three major thoracic splanchnic nerves that carry preganglionic sympathetic fibers from the thorax into the abdominal cavity. It originates from the lower thoracic sympathetic ganglia and transmits fibers that primarily influence midgut structures by synapsing in the aorticorenal ganglion or renal plexus.
The lesser splanchnic nerve arises from the 10th and 11th thoracic sympathetic ganglia. These ganglia receive preganglionic fibers from the lateral horn of spinal cord segments T10 and T11. The nerve typically appears as a single bundle, though variations can include multiple small fascicles.
From its origin in the lower thoracic sympathetic chain, the lesser thoracic splanchnic nerve descends medially and slightly inferiorly through the posterior thoracic cavity. It travels along the vertebral column and passes through the diaphragm—either via the crus or through a separate small foramen—to reach the retroperitoneum of the upper abdomen.
After passing through the diaphragm, the lesser splanchnic nerve synapses in the aorticorenal ganglion, located near the origin of the renal arteries. Some fibers may also contribute directly to the renal plexus, supplying the kidneys and upper ureter.
The lesser splanchnic nerve is composed of: