NERVE SUPPLY TO EYE.pptx NERVE SUPPLY TO EYE

NERVE SUPPLY TO EYE

1. Nerve Supply to Eye G K K M. Optom Asst. Prof MRU

2. Sensory nerves: Ophthalmic nerve: Ophthalmic nerve, smallest of the three divisions of trigeminal (5th cranial) nerve, supplies the various ocular structures through its three branches : Lacrimal nerve: It lies in the lateral part of the orbit and supplies lacrimal gland, conjunctiva and lateral part of upper eyelid . 2. Frontal nerve: It divides into two branches in the middle of orbit : ■ Supratrochlear nerve supplies the conjunctiva, middle part of upper eyelid, and skin of the forehead above the root of nose . ■ Supraorbital nerve supplies the conjunctiva , central part of upper eyelid , and part of the skin of forehead and scalp.

3. 3. Nasociliary nerve . ■ Long ciliary nerves , two in number, pierce the sclera on either side of optic nerve, run forward between sclera and choroid and supply sensory nerves to the ciliary body, iris and cornea . ■ Ciliary ganglion form its sensory root and their fibres pass along the short ciliary nerves , to supply the ciliary body, iris and cornea . ■ Posterior ethmoidal nerve supplies the ethmoidal and sphenoidal air sinuses . ■ Anterior ethmoidal nerve is a terminal branch of nasociliary nerve which leaves the orbit through the anterior ethmoidal foramen . ■ Infratrochlear nerve is the other terminal branch of nasociliary nerve . It runs forward and supplies the conjunctiva , lacrimal sac, caruncle , and medial part of the eyelids.

4. Motor nerves Extra-Ocular M uscles: • 3 rd Cranial Nerve Supply to: Medial rectus Inferior rectus Superior rectus Inferior Oblique 4 th Cranial Nerve Supply to Superior Oblique 6th cranial nerves supply to Lateral rectus . • 7th cranial nerve supply the orbicularis oculi muscle of the eyelids .

5. Autonomic nerves Parasympathetic nerves Edinger-Westphal nucleus: L ocated in midbrain , sends preganglionic fibres through the third cranial nerve to ciliary ganglion and accessory ganglion. Postganglionic nerve fibres from ciliary ganglion travel along the short ciliary nerves to supply the sphincter pupillae muscle and postganglionic fibres from the accessory ganglion supply the ciliary muscle . Salivatory nucleus : L ocated in pons , sends preganglionic fibres through facial nerve to the sphenopalatine ganglion . Postganglionic secretomotor fibres finally reach the lacrimal gland through the lacrimal nerve.

6. Course of parasympathetic nerve supply from Edinger-Westphal nucleus to ciliary muscle and sphincter pupillae muscle

7. Ciliary ganglion Ciliary ganglion is a peripheral parasympathetic ganglion placed in the course of oculomotor nerve near the apex of orbit. Roots of ciliary ganglion include : ■ Sensory root, as described above, comes from the nasociliary nerve . ■ Sympathetic root of ciliary ganglion comes from internal carotid plexus. These fibres also do not relay here and pass along the short ciliary nerves to supply the blood vessels of the eyeball . ■ Parasympathetic root of ciliary ganglion arises from the nerve to inferior oblique muscle and carries the preganglionic fibres from the Edinger–Westphal nucleus . These fibres relay here and postganglionic fibres pass through the short ciliary nerves and supply the sphincter pupillae and ciliary muscle . Short ciliary nerves, branches of ciliary ganglion, about 10 in number, pierce the sclera around the optic nerve and run forward between the sclera and choroid and reach the ciliary muscles where the sensory fibres form a plexus and supply it.

8. Course of parasympathetic nerve supply from lacrimatory nucleus to the lacrimal gland

9. Sympathetic nerves Preganglionic fibres arise from the ciliospinal center of Budge (located in inferio mediolateral cell column of spinal cord at C8, T1 and T2 level) and go to cervical sympathetic chain to relay in the superior cervical ganglion . Postganglionic fibres from the superior cervical ganglion enter the skull with the internal carotid plexuses and supply following structures : Orbital arteries receive vasomotor fibres through the plexuses around ophthalmic artery . Dilator pupillae muscle is supplied by the sympathetic fibres from the carotid plexuses which enter the Gasserian ganglion of 5th cranial nerve and ultimately reach the dilator pupillae muscle along with long ciliary branches of nasociliary nerve (branch of ophthalmic division of 5th nerve ). ■ ■

10. Blood vessels inside the eyeball are supplied by the fibres from the internal carotid plexuses which join the ciliary ganglion as its sympathetic root and without relaying here these fibres enter inside the eyeball along the short ciliary nerves. These fibres may also supply the dilator pupillae muscle when it is not supplied by the usual course via the nasociliary nerve. Palpebral (Muller’s) muscle of the eyelid is supplied by the postganglionic fibres forming cavernous plexuses reaching the muscle through the branches of oculomotor (3rd cranial) nerve.

11. Course of ocular sympathetic nerves