Nerve Supply Of Iris

Nerve supply The iris receives its sensory and autonomic nerve supply from the long and short ciliary nerves. Motor NS -- Cranial nerve 3rd 4th6th for ocular movements.

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Cranial nerve 7th for eyelid closure.

Nerve supply of iris. This double membrane is often considered continuous with the retina and a rudiment of the embryological correspondent to the retina. The inner layer is unpigmented until it reaches the iris where it takes on pigment. The short ciliary nerves then run forward and pierce the sclera at the back of the eye traveling between the sclera and the choroid to innervate the iris sphincter muscle.

The third nerve also supplies the levator palpebra. Sphincter pupillae is a circular muscle about 1 millimeter wide. Many fish have neither and as a result their irides.

Pigmented cells melanocytes clump cells Non-pigmented cells fibroblasts lymphocytes macrophages mast cells. Olfactory Nerve CN I Optic Nerve CN II Oculomotor Nerve CN III Trochlear Nerve CN IV Trigeminal Nerve CN V Abducens Nerve CN VI Facial Nerve CN VII Vestibulocochlear Nerve CN VIII Glossopharyngeal Nerve CN IX Vagus Nerve CN X Accessory Nerve CN XI Hypoglossal Nerve CN XII Blood Vessels CSF. The nerve supply of the iris deserves special attention.

It runs with the lacrimal nerve to supply the lacrimal gland. The dilator pupillae innervated by sympathetic nerves from the superior cervical ganglion cause the pupil to dilate when they contract. These postganglionic fibers will then pass anteriorly to supply two intrinsic muscles of the eye.

The retina ends at the ora serrata. Together with the sphincter pupillae the ciliary muscle functions are mainly instructed by the parasympathetic nerve fibers of oculomotor nerve CN III. The pupillary dilator consists of a spokelike arrangement of modified contractile cells called myoepithelial cells.

Nerve supply of the ciliary body Sensory fibres run from the nasociliary branch of the ophthalmic division of the trigeminal nerve as the long ciliary nerve These fibres enter the ciliary body and terminate in iris cornea and ciliary muscle Sensory Nerves. These muscles dilate and constrict the pupil in response to sympathetic and parasympathetic nerve impulses from the long ciliary nerve and oculomotor nerve III respectively. The circular muscle fibres are supplied by the short ciliary nerve branch of the motor oculi or third cranial nerve coming directly from the brain.

These may be inherited or acquired but either shows that the individual has some degree of nerve tension or anxiety. Nerve rings are depressions in the iris stroma and also are referred to as neurovascular cramp rings cramp rings contraction rings or nerve rings. Superioris and indirectly the iris and ciliary muscle of the eyeball through the ciliary ganglion.

All these muscles are supplied by the third nerve except the superior oblique which is supplied by the fourth and the external rectus which is supplied by the sixth. These fibers innervate the dilator pupillae. It is located in the pupillary zone of stromal layer of the iris attaching to and encircling the pupillary margin of iris.

They can also indicate mineral deficiencies especially calcium. When stimulated the cells contract widening the pupil and allowing more light to enter the eye. These cells are stimulated by the sympathetic nervous system.

Iris stroma Iris stroma forms the main bulk of iris tissue and contains sphincter pupillae dilator pupillae muscles vessels and nerves Cells in iris stroma. NERVE SUPPLY Sensory NS Trigeminal nerve Mixed nerve V Ophthalmic V1 MaxillaryV2 divison play main role of eye sensation. The muscle itself consists of six to eight circles of smooth muscle fibers between of which are found the nerves and blood vessels that supply each fiber.

The muscle cells of the iris are smooth muscle in mammals and amphibians but are striated muscle in reptiles including birds. Radial ridges extend from the periphery to the pupillary zone to supply the iris with blood vessels. Intraocular part optic nerve head Cilioretinal artery Peripapillary choroidal vessels Vessels from zinn and heller Surface nerve fiber layer and Prelaminar part Short Posterior Ciliary Arteries Lamina cribrosa region Central retinal artery Pial vessels Retrolaminar 27.

The iris dilator muscle is a smooth muscle of the eye running radially in the iris and therefore fit as a dilator. The iris has radially-arranged dilator pupillae muscles and concentrically-arranged sphincter pupillae muscles. The root of the iris is the thinnest and most peripheral.

The preganglionic branch carries parasympathetic nerve fibers that will synapse with parasympathetic postganglionic fibers within the ganglion. The contraction of the ciliary muscle loosens the zonular fibers increasing the convexity of the lens which induces accommodation for near vision. These muscles are sometimes referred to as intrinsic eye muscles.

The long ciliary nerves are branches of the nasociliary branch of the ophthalmic division of the trigeminal nerve. The terminal branches of the artery pass through the lacrimal gland and supply the eyelids and conjunctiva as the lateral palpebral arteries and pass medially to supply the upper and lower eyelids respectively. When the sphincter pupillae contract the iris decreases or constricts the size of the pupil.

Blood supply of Optic Nerve.

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