zonule of Zinn
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a small zone.
ciliary zonule (zonule of Zinn) a series of fibers connecting the ciliary body and lens of the eye, holding the lens in place.
zonule of Zinn
a ligament composed of straight fibrils radiating from the ciliary body of the eye to the crystalline lens, holding the lens in place and relaxing by the contraction of the ciliary muscle. Relaxation of the ligament allows the lens to become more convex. Also called zonula ciliaris.
Zinn, Johann(zin, tsin)
Johann Gottfried Zinn, Ger. anatomist and botanist, 1727–1759.
annulus of Zinn
A ring of fibrous tissue behind the eye that surrounds the optic nerve and the ophthalmic artery and vein. It consists of the origins of five of the extraocular muscles: the superior oblique, and the inferior, lateral, medial, and superior rectus muscles.Synonym: annular tendon
tendon of Zinn
The portion of the fibrous ring (annulus tendineus communis) from which the inferior rectus muscle of the eye originates.
zonule of ZinnCiliary zonule.
zonule(zon'ul?) [ zonula]
1. A small band or area. Synonym: zonula
2. The ciliary zonule.
zonule of ZinnSee: Zinn, Johann
Zinn, zonule of
A series of fibres passing from the ciliary body to the capsule of the lens at or near its equator, holding the lens in position and enabling the ciliary muscles to act upon it. The lens and zonule form a diaphragm that divides the eye into a small anterior area, which contains aqueous humour, and a larger posterior area, which contains vitreous humour. The zonule forms a ring that is roughly triangular in a meridional section. It is made up of fibres that are transparent and straight for the most part. The tension of these fibres varies with the state of contraction of the ciliary muscle and thus affects the convexity of the lens. The zonule of Zinn is made up of many non-cellular fibres, the fibrils of which consist of a cysteine-rich microfibrillar component of the elastic system, fibrillin. The fibres have been classified as follows: (1) The hyaloid zonule (orbiculo-posterior capsular fibres) which originate from the pars plana of the ciliary body and insert into the capsule just posterior to the equator at the edge of the patellar fossa. (2) The anterior zonule (orbiculo-anterior capsular fibres or anterior zonular sheet), which originate from the pars plana of the ciliary body and insert into the capsule just anterior to the equator. These are the strongest and thickest of the zonular fibres. (3) The posterior zonule (cilio-posterior capsular fibres or posterior zonular sheet), which originate from the pars plicata of the ciliary body and insert into the lens capsule posterior to the equator. These are the most numerous. (4) The equatorial zonule (cilio-equatorial fibres) which originate from the pars plicata of the ciliary body and insert into the lens capsule at the equator. Syn. suspensory apparatus of the lens; suspensory ligament; zonular fibres. See Hannover's canal; canal of Petit; ciliary processes; ora serrata.