True about Thoracic pa of sympathetic trunk:

Thoracic Pa of the Sympathetic Trunk is continuous above with the cervical and below with the lumbar pas of the sympathetic trunk.It is the most laterally placed structure in the mediastinum and runs downward on the heads of the ribs.It leaves the thorax on the side of the body of the 12th thoracic veebra by passing behind the medial arcuate ligament. The sympathetic trunk has 12 (often only 11) segmentally arranged ganglia, each with white and gray ramus communicans passing to the corresponding spinal nerve.The first ganglion is often fused with the inferior cervical ganglion to form the stellate ganglion.BranchesThe postganglionic fibers are distributed through the branches of the spinal nerves to the blood vessels, sweat glands, and erector pili muscles of the skin.The first five ganglia give postganglionic fibers to the hea, aoa, lungs, and esophagus.The lower eight ganglia mainly give preganglionic fibers, which are grouped together to form the splanchnic nerves and supply the abdominal viscera.