View source for Edinger–Westphal nucleus

{{Not to be confused with|Accessory oculomotor nuclei}}{{Short description|One of two nuclei of the oculomotor nerve}}
{{Infobox brain
| Name            = Edinger–Westphal nucleus
| Latin           = nuclei accessorii nervi oculomotorii
| Image           = cn3nucleus-en.svg
| Caption         = Section through superior colliculus (unlabeled) showing path of [[oculomotor nerve]].
| Image2          = Gray762.png
| Caption2        = Figure showing the different groups of cells, which constitute, according to Perlia, the nucleus of origin of the oculomotor nerve.<br>1. Posterior dorsal nucleus.<br>1’. Posterior ventral nucleus.<br>2. Anterior dorsal nucleus.<br>2’. Anterior ventral nucleus.<br>3. Central nucleus.<br>4. '''Nucleus of Edinger and Westphal'''.<br>5. Antero-internal nucleus.<br>6. Antero-external nucleus.<br>8. Crossed fibers.<br>9. [[Trochlear nerve]], with 9’, its nucleus of origin, and 9", its [[decussation]].<br>10. [[Third ventricle]].<br>M, M. Median line.
| IsPartOf        =
| Components      = Provides input to [[parasympathetic root of ciliary ganglion]]
| Artery          =
| Vein            =
}}
The '''Edinger–Westphal nucleus''' also called the '''accessory''' or '''visceral oculomotor nerve''', is one of the two [[Oculomotor nerve#Nuclei|nuclei of the oculomotor nerve]] (CN III) located in the [[midbrain]].<ref name="Joyce-2022">{{Citation |last1=Joyce |first1=Christopher |title=Neuroanatomy, Cranial Nerve 3 (Oculomotor) |date=2022 |url=http://www.ncbi.nlm.nih.gov/books/NBK537126/ |work=StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30725811 |access-date=2022-08-08 |last2=Le |first2=Patrick H. |last3=Peterson |first3=Diana C.}}</ref><ref name="Sonne-2022">{{Citation |last1=Sonne |first1=James |title=Neuroanatomy, Cranial Nerve |date=2022 |url=http://www.ncbi.nlm.nih.gov/books/NBK470353/ |work=StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29261885 |access-date=2022-08-08 |last2=Lopez-Ojeda |first2=Wilfredo}}</ref><ref name="Heiland Hogan-2022">{{Citation |last1=Heiland Hogan |first1=Madeline B. |title=Neuroanatomy, Edinger–Westphal Nucleus (Accessory Oculomotor Nucleus) |date=2022 |url=http://www.ncbi.nlm.nih.gov/books/NBK554555/ |work=StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32119442 |access-date=2022-08-08 |last2=Subramanian |first2=Suriya |last3=M Das |first3=Joe}}</ref> It receives afferents from both [[Pretectal area|pretectal nuclei]] (which have in turn received afferents from the [[optic tract]]).<ref name="Yoo-2023">{{Citation |last=Yoo |first=Hannah |title=Neuroanatomy, Pupillary Light Reflexes and Pathway |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK553169/ |work=StatPearls |access-date=2023-08-15 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31985962 |last2=Mihaila |first2=Dana M.}}</ref> It contains [[parasympathetic nervous system|parasympathetic]] pre-ganglionic neuron cell bodies that synapse in the [[ciliary ganglion]].<ref name="Heiland Hogan-2022" /><ref name="Sonne-2022" /> It contributes the autonomic, parasympathetic component to the oculomotor nerve (CN III),<ref name="Yoo-2023" /> ultimately providing innervation to the [[iris sphincter muscle]] and [[ciliary muscle]] to mediate the [[pupillary light reflex]] and [[Accommodation (eye)|accommodation]], respectively.<ref name="Sonne-2022" /><ref name="Heiland Hogan-2022" /> 

The Edinger–Westphal nucleus has two parts. The first is of preganglionic fibers (EWpg) that terminate in the ciliary ganglion. The second is of centrally projecting cells (EWcp) that project to a number of [[brainstem]] structures.<ref name="Haines 2018">{{cite book |last1=Haines |first1=Duane |title=Fundamental neuroscience for basic and clinical applications |date=2018 |publisher=Elsevier |location=Philadelphia, PA |isbn=9780323396325 |page=188 |edition=Fifth}}</ref><ref name="Heiland Hogan-2022" /><ref name="pmid21452224">{{cite journal |vauthors=Kozicz T, Bittencourt JC, May PJ, Reiner A, Gamlin PD, Palkovits M, Horn AK, Toledo CA, Ryabinin AE |year=2011 |title=The Edinger–Westphal nucleus: A historical, structural and functional perspective on a dichotomous terminology |journal=J. Comp. Neurol. |volume=519 |issue=8 |pages=1413–34 |doi=10.1002/cne.22580 |pmc=3675228 |pmid=21452224}}</ref>

==Structure==

The Edinger–Westphal nucleus refers to the adjacent population of non-preganglionic neurons that do not project to the [[ciliary ganglion]], but rather project to the [[spinal cord]], [[dorsal raphe nucleus]], lateral [[septal nuclei]], [[lateral hypothalamic area]] and the [[central nucleus of the amygdala]], among other regions.<ref name="pmid21452224" /><ref name="Dos Santos 2015">{{cite journal |author=Dos Santos Junior, ED, Da Silva AV, Da Silva KR, Haemmerle CA, Batagello DS, Da Silva JM, Lima LB, Da Silva RJ, Diniz GB, Sita LV, Elias CF, Bittencourt JC |year=2015 |title=The centrally projecting Edinger-Westphal nucleus-I: Efferents in the rat brain |url=https://repositorio.unesp.br/bitstream/11449/160880/1/WOS000362309000003.pdf |journal=J. Chem. Neuroanat. |volume=68 |pages=22–38 |doi=10.1016/j.jchemneu.2015.07.002 |pmid=26206178 |hdl-access=free |hdl=11449/160880|s2cid=205769513 }}.</ref>

Unlike the classical preganglionic neurons that contain [[choline acetyltransferase]], neurons of the Edinger–Westphal nucleus contain various [[neuropeptide]]s such as [[urocortin]] and [[cocaine- and amphetamine-regulated transcript]].<ref>{{cite journal |last1=Kozicz |first1=T. |year=2003 |title=Neurons colocalizing urocortin and cocaine and amphetamine-regulated transcript immunoreactivities are induced by acute lipopolysaccharide stress in the Edinger–Westphal nucleus in the rat |journal=Neuroscience |volume=116 |issue=2 |pages=315–20 |doi=10.1016/S0306-4522(02)00772-8 |pmid=12559087|s2cid=11251849 }}</ref>

Previously, it has been proposed to rename this group of non-preganglionic, neuropeptide-containing neurons to ''perioculomotor subgriseal neuronal stream'' (''pIII<sub>SG</sub>'').<ref name="pmid18186029">{{cite journal |vauthors=May PJ, Reiner AJ, Ryabinin AE |date=March 2008 |title=Comparison of the Distributions of Urocortin Containing and Cholinergic Neurons in the Perioculomotor Midbrain of the Cat and Macaque |journal=J. Comp. Neurol. |volume=507 |issue=3 |pages=1300–16 |doi=10.1002/cne.21514 |pmc=2863095 |pmid=18186029}}</ref> It has also been suggested that the preganglionic oculomotor neurons within the Edinger–Westphal nucleus be referred to as the ''EWpg'', and the neuropeptide-containing neurons be known as the centrally-projecting Edinger Westphal nucleus, or ''EWcp''.<ref name="pmid21452224" />

=== Anatomical relations ===
The paired nuclei are [[Posterior (anatomy)|posterior]] to the main motor nucleus ([[oculomotor nucleus]]) and anterolateral to the [[cerebral aqueduct]] in the [[Anatomical terms of location#Directional terms|rostral]] [[midbrain]] at the level of the [[superior colliculus]].

It is the most rostral of the parasympathetic nuclei in the [[brain stem]].

==Function==
The Edinger–Westphal nucleus supplies [[preganglionic]] parasympathetic fibers to the [[human eye|eye]], [[Pupillary response|constricting the pupil]], [[accommodation reflex|accommodating]] the [[Lens (anatomy)|lens]], and convergence of the eyes.<ref name="KaufmanLevin2011">{{cite book|last1=Kaufman|first1=Paul L.|last2=Levin|first2=Leonard A.|last3=Alm|first3=Albert|title=Adler's Physiology of the Eye|url=https://books.google.com/books?id=1oIlvnXnJvEC&pg=PA508|year=2011|publisher=Elsevier Health Sciences|isbn=978-0-323-05714-1|pages=508}}</ref>

=== Neurophysiology ===

==== Pupillary light reflex ====
{{Expand section|date=August 2022}}
The EWN is located in the midbrain, adjacent to the oculomotor nucleus. It consists of preganglionic parasympathetic neurons that send axons through the oculomotor nerve (CN III) to synapse in the ciliary ganglion. The postganglionic fibers from the ciliary ganglion then innervate the iris sphincter muscle, leading to pupillary constriction (miosis) in response to light.

The EWN also receives modulatory feedback from the locus coeruleus (LC), a noradrenergic center in the pons. The LC integrates information about ambient illumination and cognitive states, adjusting EWN activity accordingly. This interplay allows for dynamic pupil size regulation, balancing light adaptation with cognitive demands such as attention and arousal.

The role of the EWN in the pupillary light reflex is crucial for maintaining visual acuity and protecting retinal photoreceptors from excessive light exposure. Dysfunction of the EWN can lead to neurological deficits, including impaired pupillary reflexes seen in conditions such as diabetic autonomic neuropathy, oculomotor nerve palsy, and neurodegenerative disorders.<ref name="Heiland Hogan-2022" />

== Research ==
It has also been implicated in the [[Mirror neuron|mirroring]] of pupil size in sad facial expressions. When seeing a sad face, participants' pupils dilated or constricted to mirror the face they saw, which predicted both how sad they perceived the face to be, as well as activity within this region.<ref>{{cite journal | last1 = Harrison | first1 = NA | last2 = Wilson | first2 = CE | last3 = Critchley | first3 = HD | title = Processing of observed pupil size modulates perception of sadness and predicts empathy | journal = Emotion | volume = 7 | issue = 4 | pages = 724–9 | year = 2007 | pmid = 18039039 | doi = 10.1037/1528-3542.7.4.724 }}</ref><ref>{{cite journal | last1 = Harrison | first1 = NA | last2 = Singer | first2 = T | last3 = Rotshtein | first3 = P | last4 = Dolan | first4 = RJ | last5 = Critchley | first5 = HD | title = Pupillary contagion: central mechanisms engaged in sadness processing | journal = Social Cognitive and Affective Neuroscience | volume = 1 | issue = 1 | pages = 5–17 | year = 2006 | pmid = 17186063 | pmc = 1716019 | doi = 10.1093/scan/nsl006 }}</ref>

==Eponym==
The nucleus is named for both [[Ludwig Edinger]], from [[Frankfurt]], who demonstrated it in the [[fetus]] in 1885, and for [[Karl Friedrich Otto Westphal]], from [[Berlin]], who demonstrated it in the [[adult]] in 1887.<ref>{{WhoNamedIt|synd|893}}</ref>

==Additional images==
<gallery>
 File:Gray696.png|The cranial nerve nuclei schematically represented; dorsal view. Motor nuclei in red; sensory in blue.
 File:Gray697.png|Nuclei of origin of cranial motor nerves schematically represented; lateral view.
 File:Gray698.png|Primary terminal nuclei of the afferent (sensory) cranial nerves schematically represented; lateral view. 
</gallery>

==See also==
*[[Perlia's nucleus]]

==References==
<references/>

==External links==
* [https://www1.columbia.edu/sec/itc/hs/medical/anatomy_resources/anatomy/lecture6/lecture6_files/Slide0009.gif Diagram at Columbia]
* {{BrainMaps|Edinger-Westphal%20nucleus|Edinger–Westphal nucleus}}
* {{LoyolaMedEd|Neuro/frames/nlBSs/nl18fr.htm}}
* {{cite web|url=http://www.yale.edu/cnerves/cn3/cn3_12.html|title=3-12|publisher=[[Yale School of Medicine]]|work=Cranial Nerves|archive-url=https://web.archive.org/web/20160303222022/http://www.yale.edu/cnerves/cn3/cn3_12.html|archive-date=2016-03-03|url-status=dead}}

{{Mesencephalon}}
{{Cranial nerves}}
{{Visual system}}

{{DEFAULTSORT:Edinger-Westphal nucleus}}
[[Category:Cranial nerve nuclei]]
[[Category:Oculomotor nerve]]
[[Category:Midbrain]]