The cervical sympathetic nerve trunk is located in the common carotid artery, internal carotid artery, vagus nerve and deep surface of the prevertebral fascia, with three sympathetic ganglia: upper, middle and lower. The peripheral nerves still innervate vasomotor activity, and the sympathetic nerves are also located in the orbital sphincter of the iris, pupillary dilator, lacrimal gland, and cerebral vessels. The clinical manifestations of the sympathetic syndrome are ipsilateral pupil narrowing, ptosis, sunken eyeballs, and decreased sweat secretion on the hemifacial side.