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Edinger–Westphal nucleus
Edinger–Westphal nucleus
	Section through superior colliculus (unlabeled) showing path of oculomotor nerve.
	Figure showing the different groups of cells, which constitute, according to Perlia, the nucleus of origin of the oculomotor nerve.; 1. Posterior dorsal nucleus.; 1’. Posterior ventral nucleus.; 2. Anterior dorsal nucleus.; 2’. Anterior ventral nucleus.; 3. Central nucleus.; 4. Nucleus of Edinger and Westphal.; 5. Antero-internal nucleus.; 6. Antero-external nucleus.; 8. Crossed fibers.; 9. Trochlear nerve, with 9’, its nucleus of origin, and 9", its decussation.; 10. Third ventricle.; M, M. Median line.
Details
Parts	Provides input to parasympathetic root of ciliary ganglion
Identifiers
Latin	nuclei accessorii nervi oculomotorii
MeSH	D065839
NeuroNames	498
NeuroLex ID	birnlex_822
	Anatomical terms of neuroanatomy [edit on Wikidata]

The Edinger–Westphal nucleus also called the accessory or visceral oculomotor nerve, is one of the two nuclei of the oculomotor nerve (CN III) located in the midbrain.^[1]^[2]^[3] It receives afferents from both pretectal nuclei (which have in turn received afferents from the optic tract).^[4] It contains parasympathetic pre-ganglionic neuron cell bodies that synapse in the ciliary ganglion.^[3]^[2] It contributes the autonomic, parasympathetic component to the oculomotor nerve (CN III),^[4] ultimately providing innervation to the iris sphincter muscle and ciliary muscle to mediate the pupillary light reflex and accommodation, respectively.^[2]^[3]

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.^[5]^[3]^[6]

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.^[6]^[7]

Unlike the classical preganglionic neurons that contain choline acetyltransferase, neurons of the Edinger–Westphal nucleus contain various neuropeptides such as urocortin and cocaine- and amphetamine-regulated transcript.^[8]

Previously, it has been proposed to rename this group of non-preganglionic, neuropeptide-containing neurons to perioculomotor subgriseal neuronal stream (pIII_SG).^[9] 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.^[6]

Anatomical relations

The paired nuclei are posterior to the main motor nucleus (oculomotor nucleus) and anterolateral to the cerebral aqueduct in the 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 eye, constricting the pupil, accommodating the lens, and convergence of the eyes.^[10]

Neurophysiology

Pupillary light reflex

The EWN receives feedback from the locus coeruleus about illumination of the retina in order for the EWN to adjust the size of the pupil in response to varying ambient brightness.^[3]

Research

It has also been implicated in the 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.^[11]^[12]

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.^[13]

Additional images

The cranial nerve nuclei schematically represented; dorsal view. Motor nuclei in red; sensory in blue.
Nuclei of origin of cranial motor nerves schematically represented; lateral view.
Primary terminal nuclei of the afferent (sensory) cranial nerves schematically represented; lateral view.

References

^ Joyce, Christopher; Le, Patrick H.; Peterson, Diana C. (2022), "Neuroanatomy, Cranial Nerve 3 (Oculomotor)", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30725811, retrieved 2022-08-08
^ ^a ^b ^c Sonne, James; Lopez-Ojeda, Wilfredo (2022), "Neuroanatomy, Cranial Nerve", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 29261885, retrieved 2022-08-08
^ ^a ^b ^c ^d ^e Heiland Hogan, Madeline B.; Subramanian, Suriya; M Das, Joe (2022), "Neuroanatomy, Edinger–Westphal Nucleus (Accessory Oculomotor Nucleus)", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 32119442, retrieved 2022-08-08
^ ^a ^b Yoo, Hannah; Mihaila, Dana M. (2023), "Neuroanatomy, Pupillary Light Reflexes and Pathway", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 31985962, retrieved 2023-08-15
^ Haines, Duane (2018). Fundamental neuroscience for basic and clinical applications (Fifth ed.). Philadelphia, PA: Elsevier. p. 188. ISBN 9780323396325.
^ ^a ^b ^c Kozicz T, Bittencourt JC, May PJ, Reiner A, Gamlin PD, Palkovits M, Horn AK, Toledo CA, Ryabinin AE (2011). "The Edinger–Westphal nucleus: A historical, structural and functional perspective on a dichotomous terminology". J. Comp. Neurol. 519 (8): 1413–34. doi:10.1002/cne.22580. PMC 3675228. PMID 21452224.
^ 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 (2015). "The centrally projecting Edinger-Westphal nucleus-I: Efferents in the rat brain" (PDF). J. Chem. Neuroanat. 68: 22–38. doi:10.1016/j.jchemneu.2015.07.002. hdl:11449/160880. PMID 26206178. S2CID 205769513.{{cite journal}}: CS1 maint: multiple names: authors list (link).
^ Kozicz, T. (2003). "Neurons colocalizing urocortin and cocaine and amphetamine-regulated transcript immunoreactivities are induced by acute lipopolysaccharide stress in the Edinger–Westphal nucleus in the rat". Neuroscience. 116 (2): 315–20. doi:10.1016/S0306-4522(02)00772-8. PMID 12559087. S2CID 11251849.
^ May PJ, Reiner AJ, Ryabinin AE (March 2008). "Comparison of the Distributions of Urocortin Containing and Cholinergic Neurons in the Perioculomotor Midbrain of the Cat and Macaque". J. Comp. Neurol. 507 (3): 1300–16. doi:10.1002/cne.21514. PMC 2863095. PMID 18186029.
^ Kaufman, Paul L.; Levin, Leonard A.; Alm, Albert (2011). Adler's Physiology of the Eye. Elsevier Health Sciences. p. 508. ISBN 978-0-323-05714-1.
^ Harrison, NA; Wilson, CE; Critchley, HD (2007). "Processing of observed pupil size modulates perception of sadness and predicts empathy". Emotion. 7 (4): 724–9. doi:10.1037/1528-3542.7.4.724. PMID 18039039.
^ Harrison, NA; Singer, T; Rotshtein, P; Dolan, RJ; Critchley, HD (2006). "Pupillary contagion: central mechanisms engaged in sadness processing". Social Cognitive and Affective Neuroscience. 1 (1): 5–17. doi:10.1093/scan/nsl006. PMC 1716019. PMID 17186063.
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