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|The choroid and iris. (Ciliary muscle is labeled near top.)|
|Gray's||subject #225 1011|
The ciliary muscle is a smooth muscle that affects zonular fibers in the eye (fibers that suspend the lens in position during 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). The release of tension of the zonular fibers causes the lens to become more spherical. Therefore, relaxation of the ciliary muscle causes the zonular fibers to become taught, flattening the lens, increasing long range focus.
Contraction of the lens happens when there is parasympathetic activation of the M3 muscarinic receptors on the ciliary muscles (contraction of the ciliary muscles reduces the size of the ciliary body, lessening the tension on the lens and allowing it to assume a more sperical shape for close vision).
Unlike the muscles of the iris (which receives both types of autonomic innervation), the ciliary muscle receives only parasympathetic innervation. totally
- hu:Musculus ciliaris
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