sympathetic nerves (lung)
Last reviewed 01/2018
The sympathetic supply to the lungs travel from central sympathetic nuclei inferiorly to the lateral horn cells of segments T2 to T6. From here, fibres pass out of the spinal cord to synapse in the second to fourth sympathetic trunk ganglia.
The rami from the paravertebral ganglia pass anteriorly to merge with vagal fibres within the pulmonary plexus, posterior to the carina. From the plexus on each side, sympathetic fibres accompany parasympathetic fibres as they pass into the lungs around pulmonary arteries; the ramification of the arteries is accompanied by a similar divergence of nerve fibres.
The sympathetic fibres innervate smooth muscle within the walls of bronchi and small pulmonary vessels. Activation causes bronchodilation and vasodilation.