The ciliary muscle (within the ciliary body) is a mass of smooth muscle, which runs circumfer-entially inside the globe and is attached to the scleral spur anteriorly. It consists of two main parts:
1. Longitudinal (meridional) fibres - form the outer layers and arise from the scleral spur and insert into the choroid. Contraction of this part of the muscle exerts traction on the trabecular meshwork and also the choroid and retina.
2. Circular fibres - form the inner part and run circumferentially. Contraction moves the ciliary processing inwards towards the center of the pupil leading to relaxation of the zonules.
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