Eye

Purpose of optic chiasm

where nerve fibers cross over to be processed in brain

Tears drain into…

nasolacrimal duct into nasal cavity

Lacrimal gland innervation

Parasympathetic: CN 7 (pterygopalatine ganglion)

Sympathetic: superior cervical ganglion

What gives eyelids their shape?

tarsal plates

What muscle raises eyelid?

levator palpebrae superioris

Thin, transparent membrane that covers eyeball and lines eyelids

conjunctiva

6 eye muscles

superior oblique, inferior oblique, superior rectus, inferior rectus, lateral rectus, medial rectus

Fibrocartilaginous pulley for superior oblique

Trochlea

Strabismus

muscle weakness in one eye

H test

test function of individual muscles

Ophthalmic artery

branch of internal carotid, through optic canal

Ophthalmic veins

drain into facial vein & cavernous sinus, through superior orbital fissure

Outer sclera

tough protective layer, becomes cornea

Middle choroid

vascular

Inner retina

photoreceptive sensory cells, continuous with optic nerve

Transparent, flexible structure that focuses light onto retina

Lens

Clear gel, fills posterior eyeball

Vitreous humor

Clear fluid, circulates through anterior eyeball

Aqueous humor

Choroid layer forms what…

iris and ciliary bodyI

Iris function

controls amount of light let into eyeC

Ciliary body function

controls shape of lens

Function of zonular fibers

attach ciliary body to lens

Dilation of iris

widen pupil to let light in (sympathetic)

Constriction of iris

narrow pupil to block light (parasympathetic)

Dilation of ciliary body

pulls zonular fibers taught, flattens lens, distance vision (sympathetic)

Constriction of ciliary body

zonular fibers relax, lens becomes round, near vision (parasympathetic)

Rods

sensory cells for dim light, no color

Cones

sensory cells for bright light, high-resolution color

Where optic nerves enter retina

optic disc

Area of greatest visual acuity, mostly cones

macula lutea

Supplies and drains blood from retina

Central artery and vein

All nerves involved in the orbit

2, 3, 4, 5, 6, 7