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Ciliary ganglion

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Nerve: Ciliary ganglion
Ciliary ganglion
Latin g. ciliare
Gray's subject #200 888
MeSH [1]

The ciliary ganglion is a parasympathetic ganglion located in the posterior orbit. It measures 1- 2 millimeters in diameter and contains approximately 2,500 neurons[1]. Preganglionic axons from the Edinger-Westphal nucleus form synapses with these cells. The postganglionic axons innervate two eye muscles:



Ciliary ganglion pathways


Three types of nerve fibers run through the ciliary ganglion: parasympathetic fibers, sympathetic fibers and sensory fibers. Only parasympathetic fibers form synapses in the ganglion. The other two types of nerve fibers simply pass through. In classical anatomy, the ciliary ganglion is said to have three “roots:” a parasympathetic motor root, a sympathetic root and a sensory root.

Motor rootEdit

The ciliary ganglion is a parasympathetic ganglion. Incoming parasympathetic nerve fibers form synapses with the dendrites of nerve cells within the ganglion. However, the ciliary ganglion is not simply a relay station connecting preganglionic to postganglionic nerve fibers. There are roughly twice as many incoming parasympathetic fibers as outgoing parasympathetic fibers. Neural processing occurs as incoming signals converge onto target neurons.

Presynaptic parasympathetic fibers originate in the Edinger-Westphal nucleus, the parasympathetic motor nucleus associated with the oculomotor nucleus in the brainstem. Axons from the Edinger-Westphal nucleus and the oculomotor nucleus run together in the brainstem and exit together as the oculomotor nerve (cranial nerve III). The oculomotor nerve passes through the cavernous sinus and enters the orbit through the superior orbital fissure. It divides into branches that innervate the levator palpebrae superioris and four of the six extraocular muscles. Parasympathetic fibers initially run in the inferior division of the oculomotor nerve. They exit as one or two short “motor roots” that synapse in the ciliary ganglion.

Postsynaptic parasympathetic fibers leave the ciliary ganglion in multiple (six to ten) short ciliary nerves. These nerves enter the posterior aspect of the eyeball to innervate the sphincter pupillae and ciliaris muscles. The sphincter pupillae constricts the iris. The ciliaris muscle changes the shape of the lens, allowing the eye to focus on nearby objects (accommodation). Neither of these muscles is under voluntary control.

Sympathetic rootEdit


Preganglionic sympathetic fibers originate from neurons in the intermediolateral column of the thoracic spinal cord, at the level of T1 and T2. They form synapses in the superior cervical ganglion. The ratio of incoming to outgoing fibers (the “convergence”) in this ganglion is approximately100:1. Sympathetic motor neurons in the spinal cord are controlled by supranuclear pathways that descend through the brainstem and spinal cord. Interruption of the sympathetic chain at any level (from the brainstem to the ciliary ganglion) will produce pupillary constriction (miosis) and eyelid droop (ptosis) – the classic Horner syndrome.





Sensory rootEdit

Sensory fibers from the eyeball (the cornea, iris and ciliary body) run posteriorly through the short ciliary nerves and pass through the ciliary ganglion without forming synapses. They leave the ciliary ganglion in the “sensory root”, which joins the nasociliary nerve. The nasociliary nerve is a branch of the ophthalmic nerve, one of the three branches (V1) of the trigeminal nerve. The trigeminal nerve is the main sensory nerve of the face.

Sensory fibers from other parts of the eye run through the long ciliary nerves and other peripheral branches of the ophthalmic nerve. The exact distribution of sensory fibers, like the distribution of sympathetic fibers, is anatomically variable. There are alternate pathways to the eye for both sympathetic and sensory fibers, and the precise anatomy varies from person to person. Since the result is the same regardless of how the fibers reach the eye, the presence of sympathetic and sensory fibers in the ciliary ganglion (the contributions of the “sensory” and “sympathetic” roots) is of no functional significance.


Adie tonic pupilEdit

Diseases of the ciliary ganglion produce a tonic pupil[2]. This is a pupil that does not react to light (it is “fixed”) and has an abnormally slow and prolonged response to attempted near vision (accommodation).









Adie syndromeEdit





Light-near dissociationEdit




  1. Perez GM, Keyser RB. Cell Body Counts in Human Ciliary Ganglia. Investigative Ophthalmology & Visual Science 27:1428-1431, 1986
  2. Kawasaki A. Physiology, assessment, and disorders of the pupil. Curr Opin Ophthalmol 10:394-400, 1999
  3. Thompson HS, Kardon Rh. Irene Loewenfeld, PhD Physiologist of the Pupil. J Neuroophthalmol 26:139-148, 2006
  4. Thompson HS. Adie’s Syndrome: Some New Observations. Tr. Am. Ophth. Soc. LXXV:597-626, 1977



Additional imagesEdit

External linksEdit

Template:Trigeminal nerve

|}de:Ganglion ciliare


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