# Ciliary ganglion

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Bundle of nerves, parasympathetic ganglion

Ciliary ganglion Detailed view of nerves of lateral orbit showing the ciliary ganglion immediately behind the globe of the eye. Details From Sensory root of ciliary ganglion sympathetic root of ciliary ganglion parasympathetic root of ciliary ganglion To Short ciliary nerves Identifiers Latin ganglion ciliare TA98 A14.3.02.003 TA2 6663 FMA 6964 Anatomical terms of neuroanatomy [edit on Wikidata]

The **ciliary ganglion** is a [parasympathetic](/source/Parasympathetic_nervous_system) [ganglion](/source/Ganglion) located just behind the eye in the posterior [orbit](/source/Orbit_(anatomy)). It is 1–2 mm in diameter and in humans contains approximately 2,500 [neurons](/source/Neuron).[1] The ganglion contains [postganglionic](/source/Postganglionic) parasympathetic neurons. These neurons supply the [pupillary sphincter muscle](/source/Iris_sphincter_muscle), which constricts the pupil, and the [ciliary muscle](/source/Ciliary_muscle) which contracts to make the [lens](/source/Lens) more convex. Both of these muscles are involuntary since they are controlled by the parasympathetic division of the [autonomic nervous system](/source/Autonomic_nervous_system).

The ciliary ganglion is one of four parasympathetic ganglia of the head. The others are the [submandibular ganglion](/source/Submandibular_ganglion), [pterygopalatine ganglion](/source/Pterygopalatine_ganglion), and [otic ganglion](/source/Otic_ganglion).

## Structure

Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of lesion in a Horner's syndrome.

Pathways in the Ciliary Ganglion. Green = parasympathetic; Red = sympathetic; Blue = sensory

The ciliary ganglion contains postganglionic parasympathetic neurons that supply the ciliary muscle and the pupillary sphincter muscle. Because of the much larger size of the ciliary muscle, 95% of the neurons in the ciliary ganglion innervate it compared to the pupillary sphincter.

### Roots

Main article: [Roots of the ciliary ganglion](/source/Roots_of_the_ciliary_ganglion)

Three types of axons enter the ciliary ganglion but only the preganglionic parasympathetic axons synapse there. The entering axons are arranged into three roots which join enter the posterior surface of the ganglion:

- The sensory root branches from the [nasociliary nerve](/source/Nasociliary_nerve) and travels through the ganglion forming part of the short ciliary nerves. These sensory axons supply the cornea, ciliary body and iris.

- The sympathetic root originates from the [internal carotid plexus](/source/Internal_carotid_plexus) with cell bodies in the [superior cervical ganglion](/source/Superior_cervical_ganglion). The axons pass through the ganglion and enter the eye without synapsing into the short ciliary nerves. The sympathetic root contains the postganglionic sympathetic axons that provide sympathetic supply to the blood vessels of the eye. Sometimes, they also supply the [pupillary dilator muscle](/source/Iris_dilator_muscle), however these axons usually travel from the [nasociliary nerve](/source/Nasociliary_nerve) to the [long ciliary nerves](/source/Long_ciliary_nerves) to enter the eye.

- The parasympathetic root branches from the inferior division of the [oculomotor nerve](/source/Oculomotor_nerve) and carries the preganglionic parasympathetic axons from the [Edinger-Westphal nucleus](/source/Edinger%E2%80%93Westphal_nucleus) to the ciliary ganglion. Within the ganglion the axons synapse onto the postganglionic parasympathetic neurons. These neurons project axons through the [short ciliary nerves](/source/Short_ciliary_nerves) to innervate the [ciliary muscle](/source/Ciliary_muscle) and [pupillary sphincter muscle](/source/Iris_sphincter_muscle).

### Short ciliary nerves

Exiting from the anterior surface of the ciliary ganglion are the [short ciliary nerves](/source/Short_ciliary_nerves) which contain the sensory, postganglionic sympathetic and postganglionic parasympathetic axons to the eye.

## Clinical significance

### Adie tonic pupil

Main article: [Adie syndrome](/source/Adie_syndrome)

Diseases of the ciliary ganglion produce a "tonic pupil",[2] which 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](/source/Accommodation_(eye))).

When a person with an Adie pupil attempts to focus on a nearby object, the pupil (which would normally constrict rapidly) constricts slowly. On close inspection, the constricted pupil is not perfectly round. When the person focuses on a more distant object (say the far side of the room), the pupil (which would normally dilate immediately) remains constricted for several minutes, and then slowly dilates back to the expected size.

Tonic pupils are fairly common – they are seen in roughly 1 out of every 500 people. A person with anisocoria (one pupil bigger than the other) whose pupil does not react to light (does not constrict when exposed to bright light) most likely has Adie syndrome – idiopathic degeneration of the ciliary ganglion.

#### Physiology

The strange behavior of tonic pupils was first explained by Irene Loewenfeld in 1979. The ciliary ganglion contain many more nerve fibers directed to the ciliary muscle than nerve fibers directed to the constrictor pupillae – roughly twenty times more. The ciliary muscle is also more massive than the constrictor pupillae, again by a factor of twenty. Based on these observations, Loewenfeld proposed an explanation of the tonic pupil. She noted that pathological destruction of nerve cells in the ciliary ganglion that is found in all cases of Adie pupil. In her own words:[3]

- Let’s say that in a given fresh Adie’s pupil, a random 70% of the cells in the ciliary ganglion stop working; and that, in a couple of months, these neurons re-grow and randomly re-innervate both intraocular sphincters (the ciliary muscle and the iris sphincter). Some parasympathetic light-reaction neurons that were originally destined for the iris sphincter will end up innervating the ciliary muscle. But there will not be enough of them to budge that big muscle, so there will be no detectable accommodation with exposure to light. The other way around, it is a different story. There will be plenty of accommodative neurons re-growing into the iris sphincter, and it won’t take very many of them to make a little muscle like the iris sphincter contract. This means that every time the patient accommodates her gaze to a near object, some of the innervation to the ciliary muscle will spill over into the iris and constrict the pupil.

Loewenfeld’s theory is now generally accepted. It explains the defining features of a **tonic pupil**:

- (1) The pupil does not react to light. The original light-reaction neurons have been destroyed.

- (2) Tonic constriction with attempted near vision. Aberrant regeneration of nerve fibers intended for the ciliary muscle causes abnormal, tonic contraction of the pupil with accommodation.

- (3) Segmental iris constriction. When carefully examined under magnification, the iris does not constrict uniformly with attempted near vision. Only the re-innervated segments contract, producing a slightly irregular contour to the pupil.

- (4) [Denervation supersensitivity](/source/Denervation_supersensitivity). Like any denervated muscle, the iris becomes supersensitive to its normal neurotransmitter (in this case, acetylcholine). Very weak solutions of cholinergic substances such as pilocarpine (that have no effect on the normal iris) cause the denervated iris to constrict.

Tonic pupils are usually due to *Adie syndrome*, but other diseases can denervate the ciliary ganglion. Peripheral neuropathies (such as diabetic neuropathy) occasionally produce tonic pupils. Herpes zoster virus can attack the ciliary ganglion. Trauma to the orbit can damage the short ciliary nerves. Anything that denervates the ciliary ganglion will produce a tonic pupil due to aberrant nerve regeneration.

### Adie syndrome

**Adie syndrome**[4] is tonic pupil plus absent deep tendon reflexes. Adie syndrome is a fairly common, benign, idiopathic neuropathy that selectively affects the ciliary ganglion and the spinal cord neurons involved in deep tendon reflex arcs. It usually develops in middle age, although it can occur in children. A variant of Adie syndrome, **Ross syndrome**, affects sweating as well.

Early in the course of Adie syndrome (when the cells of the ciliary ganglion have been destroyed, but before regeneration has occurred) the pupil will be fixed and dilated. The *sphincter pupillae* will be paralyzed. There will be no response to accommodation – the *ciliary muscle* is also paralyzed.

With aberrant nerve regeneration, the pupil will remain fixed, but it will constrict with attempted near vision. The constriction will be abnormal (“tonic”).

Late in the course of Adie syndrome, the pupil becomes small (as all pupils do with old age). It will still be “fixed” (it will not constrict to bright light) and it will continue to show abnormal, tonic constriction with attempted near vision.

### Light-near dissociation

In some neurological disorders, the pupil does not react to light, but it does react to accommodation. This is called **“light-near dissociation”**.

In [Adie syndrome](/source/Adie_syndrome), damage involving the ciliary ganglion manifests light-near dissociation and a tonically dilated pupil (usually on the same side).

Other causes of light-near dissociation involve damage to the brainstem,[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] where a tonic pupil is not produced. Brainstem causes of light-near dissociation include [Argyll Robertson pupil](/source/Argyll_Robertson_pupil) and [Parinaud syndrome](/source/Parinaud_syndrome).

Irene Loewenfeld is generally credited for being the first physiologist to make this distinction.

## Additional images

		- Plan of [oculomotor nerve](/source/Oculomotor_nerve).

		- The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.

		- Diagram of efferent sympathetic nervous system.

## References

1. **[^](#cite_ref-1)** Perez, GM; Keyser, RB (September 1986). "Cell body counts in human ciliary ganglia". *Investigative Ophthalmology & Visual Science*. **27** (9): 1428–31. [PMID](/source/PMID_(identifier)) [3744735](https://pubmed.ncbi.nlm.nih.gov/3744735).

1. **[^](#cite_ref-2)** Kawasaki, A (December 1999). "Physiology, assessment, and disorders of the pupil". *Current Opinion in Ophthalmology*. **10** (6): 394–400. [doi](/source/Doi_(identifier)):[10.1097/00055735-199912000-00005](https://doi.org/10.1097%2F00055735-199912000-00005). [PMID](/source/PMID_(identifier)) [10662243](https://pubmed.ncbi.nlm.nih.gov/10662243).

1. **[^](#cite_ref-3)** Thompson, HS; Kardon, RH (June 2006). ["Irene E. Loewenfeld, PhD Physiologist of the pupil"](https://doi.org/10.1097%2F01.wno.0000222970.02122.a0). *Journal of Neuro-Ophthalmology*. **26** (2): 139–48. [doi](/source/Doi_(identifier)):[10.1097/01.wno.0000222970.02122.a0](https://doi.org/10.1097%2F01.wno.0000222970.02122.a0). [PMID](/source/PMID_(identifier)) [16845317](https://pubmed.ncbi.nlm.nih.gov/16845317).

1. **[^](#cite_ref-4)** Thompson, HS (1977). ["Adie's syndrome: some new observations"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1311565). *Transactions of the American Ophthalmological Society*. **75**: 587–626. [PMC](/source/PMC_(identifier)) [1311565](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1311565). [PMID](/source/PMID_(identifier)) [613531](https://pubmed.ncbi.nlm.nih.gov/613531).

## External links

- [Anatomy figure: 29:03-04](https://web.archive.org/web/20100101010101/http://ect.downstate.edu/courseware/haonline/figs/l29/290304.htm) at Human Anatomy Online, SUNY Downstate Medical Center - "A deeper dissection of the right orbit from a superior approach."

- [Atlas image: n2a4p2](https://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/atlas/n2a4p2.html) at the University of Michigan Health System - "Branches of Trigeminal Nerve, Lateral View"

- [Cell Centered Database - Ciliary ganglion](http://ccdb.ucsd.edu/sand/main?stype=lite&keyword=ciliary%20ganglion&Submit=Go&event=display&start=1)

- [lesson3](http://www.wesnorman.com/lesson3.htm) at The Anatomy Lesson by Wesley Norman (Georgetown University) (*[orbit5](http://www.wesnorman.com/Images/orbit5.jpg)*)

- [cranialnerves](http://www.wesnorman.com/cranialnerves.htm) at The Anatomy Lesson by Wesley Norman (Georgetown University) (*[III](http://www.wesnorman.com/Images/III.jpg)*, *[V](http://www.wesnorman.com/Images/V.jpg)*)

v t e The trigeminal nerve ophthalmic (V1) frontal supratrochlear supraorbital nasociliary long ciliary infratrochlear posterior ethmoidal anterior ethmoidal external nasal sensory root of ciliary ganglion ciliary ganglion lacrimal maxillary (V2) in middle cranial fossa middle meningeal in pterygopalatine fossa zygomatic zygomaticotemporal zygomaticofacial infraorbital posterior superior alveolar middle superior alveolar anterior superior alveolar mandibular (V3) in middle cranial fossa meningeal anterior division to muscles of mastication medial pterygoid/to tensor veli palatini lateral pterygoid masseteric deep temporal buccal posterior division auriculotemporal otic ganglion lingual submandibular ganglion inferior alveolar mylohyoid mental

v t e Anatomy of the autonomic nervous system Head Sympathetic Cervical ganglia: roots long ciliary Deep petrosal Parasympathetic Ciliary ganglion Roots Short ciliary Pterygopalatine ganglion deep petrosal nerve of pterygoid canal branches of distribution: greater palatine inferior posterior nasal branches lesser palatine nasopalatine medial superior posterior nasal branches pharyngeal Submandibular ganglion Otic ganglion Neck Sympathetic paravertebral ganglia: Cervical ganglia Superior Middle Inferior Stellate ganglion prevertebral plexus: Cavernous plexus Internal carotid Thorax Sympathetic paravertebral ganglia: Thoracic ganglia prevertebral plexus: Cardiac plexus Esophageal plexus Pulmonary plexus Thoracic aortic plexus splanchnic nerves: cardiopulmonary thoracic cardiac nerves: Superior Middle Inferior Abdomen Sympathetic paravertebral ganglia: Lumbar ganglia prevertebral ganglia: Celiac ganglia Aorticorenal Superior mesenteric ganglion Inferior mesenteric ganglion prevertebral plexus: Celiac plexus Hepatic Splenic Pancreatic aorticorenal Abdominal aortic plexus Renal/Suprarenal Iliac plexus Superior mesenteric Gastric Inferior mesenteric Spermatic Ovarian Superior hypogastric hypogastric nerve Superior rectal Inferior hypogastric Vesical Prostatic / Cavernous nerves of penis Uterovaginal Middle rectal splanchnic nerves: Lumbar splanchnic nerves Enteric Submucous plexus Myenteric plexus Pelvis Sympathetic paravertebral ganglia: Sacral ganglia Ganglion impar splanchnic nerves: Sacral splanchnic nerves Parasympathetic splanchnic nerves: Pelvic splanchnic nerves Category Commons

v t e The cranial nerves Terminal (CN 0) Nuclei septal nuclei Course no significant branches Olfactory (CN I) Nuclei anterior olfactory nucleus Course olfactory bulb olfactory tract Optic (CN II) Nuclei lateral geniculate nucleus Course optic chiasm optic tract Oculomotor (CN III) Nuclei oculomotor nucleus Edinger–Westphal nucleus Branches superior parasympathetic root of ciliary ganglion inferior Trochlear (CN IV) Nucleus Branches no significant branches Trigeminal (CN V) Nuclei PSN spinal trigeminal nucleus MN TMN Course trigeminal ganglion Branches ophthalmic maxillary mandibular Abducens (CN VI) Nucleus Branches no significant branches Facial (CN VII) Near origin Intermediate nerve Geniculate Inside facial canal Greater petrosal pterygopalatine ganglion Nerve to the stapedius Chorda tympani lingual nerve submandibular ganglion At stylomastoid foramen Posterior auricular Suprahyoid digastric stylohyoid Parotid plexus temporal zygomatic buccal mandibular cervical Nuclei Facial motor nucleus Solitary nucleus Superior salivary nucleus Vestibulocochlear (CN VIII) Nuclei vestibular nuclei cochlear nuclei Cochlear nerve striae medullares lateral lemniscus Vestibular Scarpa's ganglion Glossopharyngeal (CN IX) Before jugular fossa Ganglia superior inferior After jugular fossa Tympanic tympanic plexus lesser petrosal otic ganglion Stylopharyngeal branch Pharyngeal branches Tonsillar branches Lingual branches Carotid sinus Nuclei Nucleus ambiguus Inferior salivatory nucleus Solitary nucleus Vagus (CN X) Before jugular fossa Ganglia superior inferior After jugular fossa Meningeal branch Auricular branch Neck Pharyngeal branch Pharyngeal plexus Superior laryngeal external internal Recurrent laryngeal Superior cervical cardiac Thorax Inferior cardiac Pulmonary Vagal trunks anterior posterior Abdomen Celiac Renal Hepatic Anterior gastric Posterior gastric Nuclei Nucleus ambiguus Dorsal nucleus of vagus nerve Solitary nucleus Accessory (CN XI) Nuclei nucleus ambiguus spinal accessory nucleus Cranial Spinal Hypoglossal (CN XII) Nucleus Branches lingual

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Adapted from the Wikipedia article [Ciliary ganglion](https://en.wikipedia.org/wiki/Ciliary_ganglion) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Ciliary_ganglion?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.