13-1: Eye Anatomy Flashcards
Only the ___ 1/6 of the eye is visible; the rest is protected by a ___.
anterior; bony orbit in the skull
What are the three tunics of the eyeball?
Fibrous tunic (outer) Vascular tunic (middle) Sensory tunic (retina
fibrous tunic
outer coat of eyeball - has two regions (sclera and cornea)
sclera
white coat of hard, dense fibrous connective tissue that covers the eyeball except for the most anterior part (“the white of the eye”). Gives the eyeball shape and protects the inner parts
cornea
nonvascular, transparent fibrous coat in very front of eye; iris can be seen through it. Well supplied with nerve endings, touch results in reflexive blink
vascular tunic
middle coat of the eyeball, has three parts (choroid, ciliary body, iris)
choroid
thin, dark reddish brown lining inside sclera at back 2/3 of eye; contains many blood vessels and a lot of brown pigment. This pigment absorbs light rays to prevent reflection within eye; blood vessels nourish the retina
ciliary body
thick, vascular ring of tissue that encircles the lens; joins to the choroid at a saw-toothed edge called the ora serrata. Made of ciliary muscles that alter shape of lens
ora serrata
saw-tooth edge joining the ciliary body to the choroid
ciliary processes
folds on the inner surface of the ciliary body that secrete aqueous humor
iris
colored ring seen through the cornea; made of smooth muscle that contracts to regulate the amount of light hitting the retina. Located between the cornea and the lens, attached to ciliary body posteriorly
pupil
hole in the middle of iris
sensory tunic
retina; delicate inner coat; only in posterior of the eye. Responsible for image formation; made of 3 types of neurons (photoreceptors, bipolar neurons; ganglion)
photoreceptors
sensory neurons that are stimulated by light; located next to the choroid. Called rods or cones based on shape.
rods
used for dim light and peripheral vision. They are more sensitive to light than the cones, but do not provide sharp image or color vision
cones
specialized for color vision and visual acuity/sharpness in bright light.
The ___ of the ___ is the area of sharpest vision because of the high number of ___.
fovea centralis; macula lutea; cones
bipolar neurons
impulse from rods and cones is conducted next to these, which in turn conduct it to the third inner layer of neurons called ganglion cells
ganglion cells
neurons that generate a nerve impulse that is conducted down their axons which leave the eye through the optic disc
The axons of ganglion cells leave the eye through the ___, aka the ___, which is part of the __ nerve.
optic disc; blind spot; optic nerve
lens
biconvex, transparent, flexible structure made of proteins; located behind the pupil and iris. Focuses light rays on the retina
The lens is held in place by the ___, which attach it to the ___.
suspensory ligaments; ciliary muscle
cataract
clouding of the lens that often results in blindness
Internal cavities
anterior cavity: space in front of the lens
posterior cavity: space between lens and retina
The anterior cavity is divided into:
anterior chamber: behind cornea and in front of iris
posterior chamber: between iris and lens
aqueous humor
clear, watery fluid filling anterior cavity
Continuously secreted into posterior chamber by ciliary processes
flows through pupils into anterior chamber
Drains into canal of schlemm
back into blood
Aqueous humor drains into the Canal of ___
Schlemm
glaucoma
if drainage of aqueous humor is blocked, pressure within eye may increase to dangerous levels, damaging the retina and optic nerve, often causing blindess
vitreous humor
clear gel filling posterior cavity; maintains shape of eyeball and keeps the retina against the choroid. Not continously replaced
lacrimal apparatus
group of structures that make and drain tears
lacrimal gland
lies within orbit above lateral end of eyeball. Continously secretes lacrimal secretion (watery solution containing salts and mucus) which cleans, lubricates, and moistens the eye; is spread over the surface by blinking the eyeball
What structures drain the lacrimal secretion into the nasal cavity?
lacrimal canal > lacrimal sac > nasolacrimal duct
watery eyes
over-secretion of lacrimal glands; accumulate faster than can drain into the nose; excess tears spill over edges of eyelids
superior rectus
top and straight back
inferior rectus
bottom and straight back
lateral rectus
lateral side, straight back
medial rectus
medial side, straight back
superior oblique
top, at an angle
inferior oblique
bottom, at an angle
extrinsic eye muscles controled by cranial nerve VI
lateral rectus
extrensic eye muscles controlled by cranial nerve IV
superior oblique
extrenisc eye muscles controlled by cranial nerve III
superior rectus, inferior rectus, medial rectus, inferior oblique
