Head & Neck VIII: Eye & Orbit

cornea: significance

innervated with sensory nerves from trigeminal (ophthalmic) nerves & provides most of the refractive power of the eye

middle vascular layer: components

choroid, ciliary body, iris

choroid: location + function

between sclera and retina; supplies the retina

ciliary body: function + innervation

secrete aqueous humor and allows for near-sight; innervated by parasympathetic nerve fibers in oculomotor nerve

iris: general function

regulates the amount of light entering the pupil and affects focusing depth by altering the size of the pupil

dilator pupillae: action + innervation

dilates the pupil; innervated by sympathetic nerve fibers from superior cervival ganglion

sphincter pupillae: action + innervation

constricts the pupil; innervated by parasympathetic fibers in oculomotor nerve

optic disc: function

where optic nerves leaves eyeball

macula lutea: function

crucial for high resolution central vision (reading, driving, recognizing faces)

what structure contains a high concentration of cone photoreceptors?

macula lutea

what structure has the highest visual acuity?

fovea centralis

true or false: ciliary and iridial retina are light sensitive

false

cornea: function

provides refraction; fixed focal length

aqueous humor: location

posterior to anterior chamber, drains into venous system. no focusing power

lens: actions

less focusing power than cornea, but able to change focal length

vitreous body: function

fill space between lens and retina; no focusing power

blood supply of eye & orbit

branches of ophthalmic artery from the internal carotid artery

venous drainage is via the ophthalmic veins, which can also drain into what?

facial vein or into cavernous sinus (bad)

when looking forward at objects an infinite distance away, the () corresponds to an anteriorposterior line passed through the center of the eyeball

visual axis

the () deviates () to the visual axis

orbital axis; lateral (away)

levator palpebrae superioris: actions

elevates upper eyelid

lateral rectus: actions

ABduct eyes

medial rectus: actions

ADduct eye

superior rectus: actions

elevate and ADduct eye

inferior rectus: actions

depress and ADduct

superior oblique: actions

depress and ABduct eye

inferior oblique: actions

elevate and ABduct eye

what eye muscles are most effective when the eye is ABducted?

superior and inferior recti muscles

which eye muscles are most effective when the eye is ADducted?

superior and inferior obliques

lateral rectus: innervation

abducens nerve

superior oblique: innervation

trochlear nerve