Ciliary muscle 1425466 212984862 2008-05-17T05:00:35Z Arcadian 104523 nav {{Infobox Muscle | Name = {{PAGENAME}} | Latin = musculus ciliaris | GraySubject = 225 | GrayPage = 1011 | Image = Gray872.png | Caption = The [[choroid]] and [[Iris (anatomy)|iris]]. (Ciliary muscle is labeled near top.) | Image2 = | Caption2 = | Precursor = | System = | Origin = | Insertion = | Blood = [[Long ciliary arteries]] | Vein = [[Vorticose vein]] | Nerve = [[Oculomotor nerve]] ([[parasympathetic]]s) | Lymph = | Action = [[Accommodation reflex|accommodation]] | MeshName = | MeshNumber = | DorlandsPre = m_22 | DorlandsSuf = 12548589 | }} The Ciliary Muscle is a muscle in the eye that controls the eye's accommodation for viewing objects at varying distances. ==Mode of action== The ciliary muscle affects [[zonule of Zinn|zonular fibers]] in the [[eye]] (fibers that suspend the [[Lens (anatomy)|lens]] in position during [[accommodation of the eye|accommodation]]), enabling changes in lens shape for light focusing. When the ciliary muscle contracts, it releases the tension on the lens caused by the zonular fibers (fibers that hold or flatten the lens). This release of tension of the zonular fibers causes the lens to become more spherical, adapting to short range focus. The other way around, relaxation of the ciliary muscle causes the zonular fibers to become taut, flattening the lens, increasing long range focus. ==Innervation== Contraction of the lens happens when there is [[parasympathetic]] activation of the M3 [[muscarinic receptors]] on the ciliary muscles. The parasympathetic signal is carried by cranial nerve III (the [[oculomotor nerve]]) synapsing on the [[ciliary ganglion]]. This leads to contraction of the ciliary muscles, a consequent reduction in the size of the ciliary body, and a lessening of the tension on the lens, hence allowing the lens to spring back into a more spherical shape to accommodate for close vision. Unlike the muscles of the iris (which receives both types of autonomic innervation--the [[iris sphincter]] is exclusively innervated by parasympathetics and the [[iris dilator]] exclusively by sympathetics), the ciliary muscle receives only parasympathetic innervation. ==See also== *[[accommodation reflex]] *[[Ciliary body]] *[[Cycloplegia]] *[[Presbyopia]] *[[Edinger-Westphal nucleus]] ==Additional images== <gallery> <Image:Gray840.png|Sympathetic connections of the ciliary and superior cervical ganglia.> Image:Gray873.png|The arteries of the choroid and iris. The greater part of the sclera has been removed. Image:Gray878.png|Iris, front view. </gallery> ==External links== * {{eMedicineDictionary|Ciliary+muscle}} {{Eye}} {{Visual system}} {{muscle-stub}} [[Category:Muscles of the head and neck]] [[Category:Eye]] [[hu:Musculus ciliaris]] [[pl:Mięsień rzęskowy]] [[sk:Vráskovec]] [[sr:Цилијарни мишић]] [[sh:Cilijarni mišić]]