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
The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit. Three types of axons enter the ciliary ganglion but only the preganglionic parasympathetic axons synapse there. The entering axons are arranged into three roots of the ciliary ganglion, which join enter the posterior surface of the ganglion.
| Ciliary ganglion | |
|---|---|
 Pathways in the Ciliary Ganglion. Green = parasympathetic; Red = sympathetic; Blue = sensory | |
| Anatomical terms of neuroanatomy |
