The cervical sympathetic trunks are three ganglia that provide sympathetic innervation to the head, neck, and upper thoracic region, including the heart.
The three ganglia emerge from and are essentially an expansion of the thoracic paravertebral sympathetic trunk.
This is because the cervical spinal cord does not contain neurons that provide sympathetic innervation (lateral horn), therefore, it has to “pull it” from an external source — the thoracic lateral horns.
As we’ve discussed earlier, post-ganglionic fibers of the sympathetic trunk are