EYE
The eye is an
extension of
the brain
It helps us take
in light
information
from our
surroundings.
This is how!
Eye brain
proximity
• Can you see :
• the optic
nerve bundle?
• Spinal cord?
What are the parts of the eye?
• Let’s use a diagram to help us get familiar with
the parts and pronounce them correctly!
Cornea
Cornea- transparent membrane that covers iris and
pupil. Focuses light on the retina.
Pupil, Iris, Sclera
Pupil- hole passes different amounts of light
Iris- colored part of the eye that controls the size of
the pupil
Sclera- “whites” of the eye that forms outer covering
Aqueous Humor, Ciliary Muscle, Lens
Aqueous Humor- nutritious fluid between the iris and
the cornea. As we age, it breaks down and we begin
to see “floaters”
Ciliary Muscles- produces aqueous humor and
controls lens shape
Lens- Bends light rays to the back of the eye –retina.
Elastic so change in shape allows for focus on
objects close up or far away
Retina
• Full of light
receptors
which are
Blind Spot- site of
optic nerve
sensitive
connection to:
• Cones-
Colour
• Rods- Light
levels
• Massive
blood
supply is
also
This is Ms. Vikingson’s retina!! needed
Vitreous Humor, Blind Spot, Optic Nerve,
Vitreous Humor- transparent jelly-like fluid that fills
the eye and refracts light
Optic Nerve- sends messages
picked up by retina to the brain
Blind Spot- area where optic
nerve attaches. No retina is
located there so information
cannot be picked up; “Blind”
Choroid Layer, Tapetum lucidum
Choroid Layer- lies between the
sclera and the retina it provides
the blood supply to the eye.
Tapetum lucidum- iridescent film
under the retina that provides
animals with “night vision”
Cross Sclera
section Choroid Layer
You must know: Taptem lucidum
1. Lens
2. Cornea
3. Aqueous humor
4. Pupil
Blind
5. Iris Spot
6. Ciliary Muscle
7. Sclera
8. Vitreous Humor
9. Retina
10. Blind Spot
11. Choroid Layer Ciliary
12. Optic Nerve
13. Tapetum Lucidum
Eye Dissection
• Before we go over the dissection, let’s review
the parts of the eye and their function
TIME TO BEGIN THE DISSECTION!!!
Cow-Eye Interactive Dissection
Cut away fat using scissors
Anterior External Eye Structure
Posterior External Eye Structures
• Select a place to make an incision of the sclera midway
between the cornea and optic nerve. Use the point of a
surgical scissors to make a small cut through the sclera.
Fluid should ooze out of the eyeball when you have cut
deeply enough.
• Arrange the two hemispheres of the eye as you see in the
photograph.
• Observe the semi-fluid vitreous humor that fills the central
cavity of the eye. It is transparent in the living eye but might
be cloudy in the preserved specimen
• The retina lines the the posterior cavity of the eye and
extends forward to the ciliary body. Use your probe to lift and
pull the retina back from the underlying choroid layer.
• Notice that the retina is only firmly attached to the choroid at
one place. This region is the optic disc or blind spot.
Internal Eye Structure – Posterior Section
Internal Eye Structures – Anterior Section
Remove the lens and place against
newspaper to see that it is a magnifier!
• When the lens is removed, an opening, allowing light to enter
the eye is seen. This opening, the pupil is located in the
center of the iris. Note the oblong shape of the sheep pupil,
in humans the pupil is circular.
• The back side of the iris can be seen just above the pointer in
the photograph.
Can you identify the parts? You will
need to to get credit during the lab
1. Cornea 7. Ciliary Body
2. Sclera 8. Choroid
3. Optic Nerve 9. Tapetum Lucidum
4. Iris 10. Retina
5. Pupil 11. Lens
6. Ora Serrata (you do not 12. Vitreous Humor
have to know this
structure!)
Clean up!
• Once all eye parts have been located and signed off
by your teacher, it is time to clean up!
• Clean off all instruments on your paper towel and
put them away
• Wrap up eye and all eye parts inside your paper
towel
• Remove gloves around paper towel for easy
disposal
• Place items into garbage can
Review before your quiz!
Let’s take a peek at this interactive eye and see
how many you can get correct!
Feeling comfortable? Time to take your quiz!
Top scorers will be dissection group leaders