Fig. 14. Autonomic nerve supply of the orbit. A. Parasympathetic supply. Parasagittal view of the right orbit shows the position of the ciliary ganglion on the lateral aspect of the optic nerve. Parasympathetic fibers to the globe travel through the superior orbital fissure with the nerve to the inferior oblique muscle and synapse within this ganglion. Sympathetic and nasociliary fibers pass through the ciliary ganglion without synapse. Parasympathetic fibers to the lacrimal gland synapse outside the orbit in the pterygopalatine ganglion, which lies in the pterygopalatine fossa. Fibers then join the maxillary division of the trigeminal nerve to travel along the lateral orbit with the zygomaticotemporal nerve before finally joining the lacrimal nerve and entering the lacrimal gland. B. Sympathetic supply. First-order neurons travel from the hypothalamus inferiorly within the spinal cord to synapse at the ciliospinal center of Budge (C8 to T2). Second-order neurons travel over the apex of the lung and around the subclavian artery to enter the paravertebral sympathetic chain and then synapse at the superior ciliary ganglion. From there, a plexus of third-order neurons forms surrounding the external and internal carotid artery. The external carotid artery fibers are responsible for vasoconstriction and sweating of most of the face. Within the CS, internal carotid artery fibers destined for the globe travel for a short course with the abducens nerve, then join the nasociliary nerve and enter the orbit through the superior orbital fissure. Long posterior ciliary nerves synapse in the dilator muscle of the iris. A second group of fibers enters the orbit through the optic canal as a plexus around the ophthalmic artery. These fibers then travel diffusely through the orbital soft tissue to supply orbital vessels, the superior ( Müller's) and inferior tarsal muscles, the sweat glands of the forehead, and possibly the main lacrimal gland. (A modified from Doxanas MT, Anderson RL: Clinical Orbital Anatomy, p 149. Baltimore, Williams & Wilkins, 1984. B modified from Weinstein JM, Zweifel TJ, Thompson HS: Congenital Horner's syndrome, p 1076. Arch Ophthalmol 98:1074, 1980)