Zonule of Zinn
| Zonule of Zinn | |
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| Schematic diagram of the human eye. (Zonular fibers labeled at upper left.) | |
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| The upper half of a sagittal section through the front of the eyeball. (Zonule of Zinn visible near center.) | |
| Latin | zonula ciliaris |
| Gray's | subject #226 1018 |
The zonule of Zinn (Zinn's membrane, ciliary zonule) (after Johann Gottfried Zinn) is a ring of fibrous strands connecting the ciliary body with the crystalline lens of the eye.
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Development [edit]
The ciliary epithelial cells of the eye probably synthesize portions of the zonules.[1]
Anatomy [edit]
The zonule of Zinn is split into two layers: a thin layer, which lines the hyaloid fossa, and a thicker layer, which is a collection of zonular fibers. Together, the fibers are known as the suspensory ligament of the lens.[2] The zonules are about 1–2 μ in diameter.[3]
When colour granules are displaced from the Zonules of Zinn (by friction against the lens), the irises slowly fade. In some cases those colour granules clog the channels and lead to Glaucoma Pigmentosa.
The zonules are primary made of fibrillin, a connective tissue protein.[1] Mutations in the fibrillin gene lead to the condition Marfans Syndrome, and consequences include an increased risk of lens dislocation.[1]
Clinical appearance [edit]
The zonules of Zinn are difficult to visualize using a slit lamp, but may be seen with exceptional dilation of the pupil, or if a coloboma of the iris or a suluxation of the lens is present.[4] The number of zonules present in a person appears to decrease with age.[3] The zonules insert around the outer margin of the lens (equator), both anteriorly and posteriorly.[5]
Additional Images [edit]
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Structures of the eye labeled
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This image shows another labeled view of the structures of the eye
References [edit]
- ^ a b c Kaufman, Paul L.; Alm, Albert (2010). Adler's physiology of the eye (11th ed. ed.). St. Louis, Mo: Mosby. pp. 145–146. ISBN 978-0-323-05714-1.
- ^ http://www.etsu.edu/cpah/hsci/forsman/WebVision.htm
- ^ a b Bornfeld, Norbert; Spitznas, Manfred; Breipohl, Winrich; Bijvank, Gerhard J. (1974). "Scanning electron microscopy of the zonule of Zinn". Albrecht von Graefes Archiv for Klinische und Experimentelle Ophthalmologie 192 (2): 117–129. doi:10.1007/BF00410698.
- ^ McCulloch, C (1954-1955). "The Zonule of Zinn: its Origin, Course, and Insertion, and its Relation to Neighboring Structures.". Transactions of the American Ophthalmological Society 52: 525–85. PMID 13274438. Retrieved 15 December 2012.
- ^ Farnsworth, PN; Mauriello, JA; Burke-Gadomski, P; Kulyk, T; Cinotti, AA (1976 Jan). "Surface ultrastructure of the human lens capsule and zonular attachments.". Investigative ophthalmology 15 (1): 36–40. PMID 1245377.
External links [edit]
- Diagram at unmc.edu
- Diagram at eye-surgery-uk.com
- Diagram and overview at webschoolsolutions.com
- ciliary+zonule at eMedicine Dictionary
- BU Histology Learning System: 08011loa
This article incorporates text from a public domain edition of Gray's Anatomy.
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