Posterior Mediastinum LO 7
7. What are splanchnic nerves, and which splanchnic nerves originate from the thoracic sympathetic trunk?
The thoracic sympathetic trunks typically consist of 11 (but may consist of 10-13) ganglia. Usually, the T1 ganglion fuses with the inferior cervical ganglion to become the cervicothoracic (stellate) ganglion, and thoracic ganglia are successively numbered inferiorly from the cervicothoracic ganglion. In humans, each thoracic ganglion connects with two successive spinal nerves. Connections between ganglia and spinal nerves take the form of white rami communicantes (nerves → ganglia; pre-ganglionic; myelinated) and gray rami communicantes (ganglia → nerves; post-ganglionic; unmyelinated).
Splanchnic nn. are aggregations of pre-synaptic sympathetic fibers that pass through the trunk without synapsing. These fibers ultimately synapse in pre-vertebral (pre-aortic) ganglia of the abdominal region.
The thoracic splanchnic nn. include the: