| Zonule of Zinn | |
|---|---|
 Anatomy of the anterior part of thehuman eye. "Suspensory ligaments" are labeled at left. | |
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| Details | |
| Identifiers | |
| Latin | zonula ciliaris |
| TA98 | A15.2.05.015 |
| TA2 | 6795 |
| FMA | 58838 |
| Anatomical terminology | |
Thezonule of Zinn (/ˈtsɪn/) (Zinn's membrane,ciliary zonule) (afterJohann Gottfried Zinn) is a ring of fibrous strands forming azonule (little band) that connects theciliary body with the crystallinelens of theeye.[1] The Zonular fibers are viscoelastic cables, although their component microfibrils are stiff structures. These fibers are sometimes collectively referred to as thesuspensory ligaments of the lens, as they act like suspensoryligaments.
The non-pigmented ciliary epithelial cells of the eye synthesize portions of the zonules.[2][3]
The zonule of Zinn is split into two layers: a thin layer, which lies near thehyaloid fossa, and a thicker layer, which is a collection of zonular fibers. Together, the fibers are known as the suspensory ligament of the lens.[4] The zonules are about 1–2 μm in diameter.[5]
The zonules attach to the lens capsule 2 mm anterior and 1 mm posterior to the equator, and arise of the ciliary epithelium from the pars plana region as well as from the valleys between the ciliary processes in the pars plicata.[6][7]
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 toglaucoma pigmentosa.
The zonules are primarily made offibrillin, a connective tissue protein.[2] Mutations in the fibrillin gene lead to the conditionMarfan syndrome, and consequences include an increased risk of lens dislocation.[2]
The zonules of Zinn are difficult to visualize using a slit lamp, but may be seen with exceptional dilation of the pupil, or if acoloboma of the iris or asubluxation of the lens is present.[8] The number of zonules present in a person appears to decrease with age.[5] The zonules insert around the outer margin of the lens (equator), both anteriorly and posteriorly.[9]
Securing the lens to the optical axis and transferring forces from the ciliary muscle in accommodation. When colour granules are displaced from the zonules of Zinn, caused by friction of the lens, the iris can slowly fade. These colour granules can clog the channels and lead to glaucoma pigmentosa.
This article incorporates text in thepublic domain frompage 1018 of the 20th edition ofGray's Anatomy(1918)
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