13-1: Eye Anatomy

Question 1

Only the ___ 1/6 of the eye is visible; the rest is protected by a ___.

Answer 1

anterior; bony orbit in the skull

Question 2

What are the three tunics of the eyeball?

Answer 2

Fibrous tunic (outer)
Vascular tunic (middle)
Sensory tunic (retina

Question 3

fibrous tunic

Answer 3

outer coat of eyeball - has two regions (sclera and cornea)

Question 4

sclera

Answer 4

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

Question 5

cornea

Answer 5

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

Question 6

vascular tunic

Answer 6

middle coat of the eyeball, has three parts (choroid, ciliary body, iris)

Question 7

choroid

Answer 7

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

Question 8

ciliary body

Answer 8

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

Question 9

ora serrata

Answer 9

saw-tooth edge joining the ciliary body to the choroid

Question 10

ciliary processes

Answer 10

folds on the inner surface of the ciliary body that secrete aqueous humor

Question 11

iris

Answer 11

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

Question 12

pupil

Answer 12

hole in the middle of iris

Question 13

sensory tunic

Answer 13

retina; delicate inner coat; only in posterior of the eye. Responsible for image formation; made of 3 types of neurons (photoreceptors, bipolar neurons; ganglion)

Question 14

photoreceptors

Answer 14

sensory neurons that are stimulated by light; located next to the choroid. Called rods or cones based on shape.

Question 15

rods

Answer 15

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

Question 16

cones

Answer 16

specialized for color vision and visual acuity/sharpness in bright light.

Question 17

The ___ of the ___ is the area of sharpest vision because of the high number of ___.

Answer 17

fovea centralis; macula lutea; cones

Question 18

bipolar neurons

Answer 18

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

Question 19

ganglion cells

Answer 19

neurons that generate a nerve impulse that is conducted down their axons which leave the eye through the optic disc

Question 20

The axons of ganglion cells leave the eye through the ___, aka the ___, which is part of the __ nerve.

Answer 20

optic disc; blind spot; optic nerve

Question 21

lens

Answer 21

biconvex, transparent, flexible structure made of proteins; located behind the pupil and iris. Focuses light rays on the retina

Question 22

The lens is held in place by the ___, which attach it to the ___.

Answer 22

suspensory ligaments; ciliary muscle

Question 23

cataract

Answer 23

clouding of the lens that often results in blindness

Question 24

Internal cavities

Answer 24

anterior cavity: space in front of the lens

posterior cavity: space between lens and retina

Question 25

The anterior cavity is divided into:

Answer 25

anterior chamber: behind cornea and in front of iris

posterior chamber: between iris and lens

Question 26

aqueous humor

Answer 26

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

Question 27

Aqueous humor drains into the Canal of ___

Answer 27

Schlemm

Question 28

glaucoma

Answer 28

if drainage of aqueous humor is blocked, pressure within eye may increase to dangerous levels, damaging the retina and optic nerve, often causing blindess

Question 29

vitreous humor

Answer 29

clear gel filling posterior cavity; maintains shape of eyeball and keeps the retina against the choroid. Not continously replaced

Question 30

lacrimal apparatus

Answer 30

group of structures that make and drain tears

Question 31

lacrimal gland

Answer 31

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

Question 32

What structures drain the lacrimal secretion into the nasal cavity?

Answer 32

lacrimal canal > lacrimal sac > nasolacrimal duct

Question 33

watery eyes

Answer 33

over-secretion of lacrimal glands; accumulate faster than can drain into the nose; excess tears spill over edges of eyelids

Question 34

superior rectus

Answer 34

top and straight back

Question 35

inferior rectus

Answer 35

bottom and straight back

Question 36

lateral rectus

Answer 36

lateral side, straight back

Question 37

medial rectus

Answer 37

medial side, straight back

Question 38

superior oblique

Answer 38

top, at an angle

Question 39

inferior oblique

Answer 39

bottom, at an angle

Question 40

extrinsic eye muscles controled by cranial nerve VI

Answer 40

lateral rectus

Question 41

extrensic eye muscles controlled by cranial nerve IV

Answer 41

superior oblique

Question 42

extrenisc eye muscles controlled by cranial nerve III

Answer 42

superior rectus, inferior rectus, medial rectus, inferior oblique