Ciliary muscle

Source: Wikipedia, the free encyclopedia.
Ciliary muscle
Vorticose vein
Nerveshort ciliary
Parasympathetic fibers in the oculomotor nerve (CN-III) synapse in the ciliary ganglion. Parasympathetic postganglionic fibers from the ciliary ganglion travel through short ciliary nerves into the ocular globe.
Actions1) accommodation, 2) regulation of trabecular meshwork pore sizes
Identifiers
Latinmusculus ciliaris
TA98A15.2.03.014
TA26770
FMA49151
Anatomical terms of muscle]

The ciliary muscle is an

dilator pupillae
.

Structure

Development

The ciliary muscle develops from mesenchyme within the choroid and is considered a cranial neural crest derivative.[6]

Nerve supply

Ciliary ganglion with parasympathetic fibers of ciliary nerves.

The ciliary muscle receives parasympathetic fibers from the short ciliary nerves that arise from the ciliary ganglion. The parasympathetic postganglionic fibers are part of cranial nerve V1 (Nasociliary nerve of the trigeminal), while presynaptic parasympathetic fibers to the ciliary ganglia travel with the oculomotor nerve.[7] The postganglionic parasympathetic innervation arises from the ciliary ganglion.[8]

Presynaptic parasympathetic signals that originate in the

muscarinic receptors causes ciliary muscle contraction. The effect of contraction is to decrease the diameter of the ring of ciliary muscle causing relaxation of the zonule fibers, the lens becomes more spherical, increasing its power to refract light for near vision.[citation needed
]

The parasympathetic tone is dominant when a higher degree of accommodation of the lens is required, such as reading a book.[9]

Function

Accommodation

Main article:
accommodation of the eye

The ciliary fibers have circular (Ivanoff),

meridional) and radial orientations.[11]

According to

focal distance,[12] increasing long range focus. Although Helmholtz's theory has been widely accepted since 1855, its mechanism still remains controversial. Alternative theories of accommodation have been proposed by others, including L. Johnson, M. Tscherning, and especially Ronald A. Schachar.[3]

Trabecular meshwork pore size

Contraction and relaxation of the longitudinal fibers, which insert into the

canal of Schlemm.[13]

Clinical significance

Glaucoma

Open-angle glaucoma (OAG) and closed-angle glaucoma (CAG) may be treated by muscarinic receptor agonists (e.g., pilocarpine), which cause rapid miosis and contraction of the ciliary muscles, opening the trabecular meshwork, facilitating drainage of the aqueous humour into the canal of Schlemm and ultimately decreasing intraocular pressure.[14]

History

Etymology

The word ciliary had its origins around 1685–1695.

lens of the eye.[17]

Additional images

  • The arteries of the choroid and iris. The greater part of the sclera has been removed.
    The arteries of the choroid and iris. The greater part of the sclera has been removed.
  • Iris, front view.
    Iris, front view.

See also

This article uses anatomical terminology.

References

  1. ^ a b Gest, Thomas R; Burkel, William E. "Anatomy Tables - Eye." Medical Gross Anatomy. 2000. University of Michigan Medical School. January 5, 2010 Umich.edu Archived 2010-05-26 at the Wayback Machine
  2. ISBN 978-1-4058-8118-0
    .
  3. ^
    S2CID 45247729
    .
  4. ISBN 978-9-062-99233-1
    .
  5. PMID 25750232
    .
  6. ISBN 978-1-60547-901-9
    .
  7. ISBN 0-7817-3639-0
    .
  8. PMID 25589275
    .
  9. ISBN 978-0-07-162442-8
    .
  10. ISBN 978-3-540-69144-0
    .
  11. ^ Riordan-Eva Paul, "Chapter 1. Anatomy & Embryology of the Eye" (Chapter). Riordan-Eva P, Whitcher JP (2008). Vaughan & Asbury's General Ophthalmology (17th ed.). McGraw-Hill. AccessMedicine.com Archived 2009-07-06 at the Wayback Machine
  12. ISBN 978-0-07-162442-8
    .
  13. ^ Salmon John F, "Chapter 11. Glaucoma" (Chapter). Riordan-Eva P, Whitcher JP (2008). Vaughan & Asbury's General Ophthalmology (17th ed.). McGraw-Hill. AccessMedicine.com Archived 2009-07-06 at the Wayback Machine
  14. ^ Le, Tao T.; Cai, Xumei; Waples-Trefil, Flora. "QID: 22067". USMLERx. MedIQ Learning, LLC. 2006–2010. 13 January 2010 Usmlerx.com Archived 2012-10-26 at the Wayback Machine
  15. ^ "cilia", Unabridged. Source location: Random House, Inc. Reference.com. Retrieved on 2010-01-16 from http://dictionary.reference.com/browse/cilia.
  16. ^ Dictionary.com, "-ary", in The American Heritage Dictionary of the English Language, Fourth Edition. Source location: Houghton Mifflin Company, 2004. Reference.com. Retrieved on 2010-01-16 from http://dictionary.reference.com/browse/-ary.
  17. ^ "ciliary," in Dictionary.com Unabridged. Source location: Random House, Inc. Reference.com. Retrieved on 2010-01-16 from http://dictionary.reference.com/browse/ciliary.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Ciliary_muscle&oldid=1189814271"