Figure 2. Autonomic sympathetic innervation of the face. The preganglionic supply of the eye exit the spinal cord in the first thoracic root, whereas preganglionic sudomotor and vasomotor fibers leave below T1. The rostral superior cervical ganglion projects postganglionic fibers to the eyes, forehead, and cheeks via the internal carotid nerve, whereas the caudal part of the ganglion projects postganglionic fibers to the cheeks and other parts of the face via the external carotid nerve. Numbers 1, 2, and 3 represent sympathetic lesions that may produce hemifacial loss of flushing with ocular sparing. 1 = preganglionic fibers from T2 and T3; 2 = caudal superior cervical ganglion; 3 = postganglionic fibers of the external carotid nerve.