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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 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 .
The parasympathetic innervation of the ciliary body is the most clearly understood. Presynaptic parasympathetic signals that originate in the Edinger-Westphal nucleus are carried by cranial nerve III (the oculomotor nerve) and travel through the ciliary ganglion. Postsynaptic fibers from the ciliary ganglion form the short ciliary nerves.
The ophthalmic nerve (CN V 1) is a sensory nerve of the head. It is one of three divisions of the trigeminal nerve (CN V) , a cranial nerve . It has three major branches which provide sensory innervation to the eye , and the skin of the upper face and anterior scalp , as well as other structures of the head.
[1] These neurons show roughly circular receptive fields with antagonistic center and surround; this property is known as spatial opponency and these neurons are typically divided into ON- or OFF-center, depending on whether they are excited or inhibited by photons falling on the center of their receptive fields. [ 2 ]
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.
Postganglionic sympathetic fibres ascend from the superior cervical ganglion, along the walls of the internal carotid artery, to enter the internal carotid plexus. These fibres are then distributed to deep structures, including the superior tarsal muscle and pupillary dilator muscle. [2]
In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus. [1] [2]