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The ciliary ganglion contain many more nerve fibers directed to the ciliary muscle than nerve fibers directed to the constrictor pupillae – roughly twenty times more. The ciliary muscle is also more massive than the constrictor pupillae, again by a factor of twenty. Based on these observations, Loewenfeld proposed an explanation of the tonic ...
The ciliary muscle controls accommodation by altering the shape of the lens to be able to see an object from near to far. [ 2 ] The pupillary sphincter muscle and pupillary dilator muscle control the iris to adjust the size of the pupil to adjust how much light enters into the eye.
The ciliary muscle is an intrinsic muscle of the eye formed as a ring of smooth muscle [3] [4] in the eye's middle layer, the uvea (vascular layer). It controls accommodation for viewing objects at varying distances and regulates the flow of aqueous humor into Schlemm's canal .
Light from a single point of a distant object and light from a single point of a near object being brought to a focus. The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at a distant object (and vice versa), comprising coordinated changes in vergence, lens shape (accommodation) and pupil size.
Ciliary body. The anterior segment or anterior cavity [1] is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. [2] [3] Within the anterior segment are two fluid-filled spaces:
The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit. Three types of axons enter the ciliary ganglion but only the preganglionic parasympathetic axons synapse there. The entering axons are arranged into three roots of the ciliary ganglion, which join enter the posterior surface of the ganglion.
Each has three roots entering the ganglion and a variable number of exiting branches. The motor root carries presynaptic parasympathetic nerve fibers ( GVE ) that terminate in the ganglion and synapse with the postsynaptic fibers that, in turn, project to target organs.
The reflex is mediated by nerve connections between the ophthalmic branch of the trigeminal cranial nerve via the ciliary ganglion, and the vagus nerve of the parasympathetic nervous system. Nerve fibres from the maxillary and mandibular divisions of the trigeminal nerve have also been documented. [ 2 ]