Sympathetic Innervation
- Contains postganglionic sympathetic fibers
- Cell bodies located in the superior cervical ganglion
- Axons ascend with the internal carotid artery as a plexus of nerves
- Sympathetic fibers supplying the eye separate from the carotid plexus within the cavernous sinus
- Sympathetic fibers in the short ciliary nerves pass through the ciliary ganglion without forming synapses
- Originate from neurons in the intermediolateral column of the thoracic spinal cord
- Synapse in the superior cervical ganglion
- Convergence ratio in the ganglion is approximately 100:1
- Controlled by supranuclear pathways descending through the brainstem and spinal cord
- Interruption of the sympathetic chain produces pupillary constriction and eyelid droop
- Innervate blood vessels, sweat glands, and 4 eye muscles
- Dilator pupillae muscle dilates the pupil
- Superior tarsal muscle elevates the upper eyelid
- Inferior tarsal muscle and orbitalis muscle are vestigial in humans
- Pupil size is controlled by both sympathetic and parasympathetic nerves

Sensory Innervation
- Sensory fibers from the eyeball run through the short ciliary nerves
- Pass through the ciliary ganglion without forming synapses
- Join the nasociliary nerve and travel back through the ophthalmic nerve
- Relay to specific nuclei in the thalamus and cerebral cortex
- Distribution of sensory fibers is anatomically variable

Parasympathetic Innervation
- Provides parasympathetic supply to the ciliary ganglion
- Ciliary ganglion is a parasympathetic ganglion
- Roughly twice as many incoming parasympathetic fibers as outgoing fibers
- Presynaptic parasympathetic fibers originate in the Edinger-Westphal nucleus
- Postsynaptic parasympathetic fibers leave the ciliary ganglion to supply the sphincter pupillae and ciliaris muscles.

Sympathetic Root
- Contains postganglionic sympathetic fibers
- Cell bodies located in the superior cervical ganglion
- Axons ascend with the internal carotid artery as a plexus of nerves
- Sympathetic fibers supplying the eye separate from the carotid plexus within the cavernous sinus
- Sympathetic fibers in the short ciliary nerves pass through the ciliary ganglion without forming synapses
- Originate from neurons in the intermediolateral column of the thoracic spinal cord
- Synapse in the superior cervical ganglion
- Convergence ratio in the ganglion is approximately 100:1
- Controlled by supranuclear pathways descending through the brainstem and spinal cord
- Interruption of the sympathetic chain produces pupillary constriction and eyelid droop

Preganglionic Sympathetic Fibers
- Originate from neurons in the intermediolateral column of the thoracic spinal cord
- Synapse in the superior cervical ganglion
- Convergence ratio in the ganglion is approximately 100:1
- Controlled by supranuclear pathways descending through the brainstem and spinal cord
- Interruption of the sympathetic chain produces pupillary constriction and eyelid droop