Eye Anatomy and Physiology

Question 1

What muscle supplies movement of upper eyelid?

Answer 1

Levator palpebrae superioris muscle

Question 2

What is the gap between upper and lower eyelids called?

Answer 2

Palpebral fissure

Question 3

From superficial to deep what are the layers of the eyelid?

Answer 3

Epidermis
Dermis
Subcutaenous tissue
Obicularis oculi muscle
Tarsal plate
Tarsal glands
Conjunctiva

Question 4

What keeps the eyelids from sticking together?

Infection of said structure is called what?

Answer 4

Sebaceous fluid produced by the tarsal gland

Chalazion

Question 5

What structure covers the inner aspect of the eyelids?

Answer 5

Palpebral conjunctiva

Question 6

What structure covers the sclera from the eyelids?

Answer 6

Bulbar conjunctiva - it is vascular. Irritation of this is the cause of bloodshot eyes

Question 7

Infection of the sebaceous ciliary glands of the eyelashes can lead to what?

Answer 7

A stye

Question 8

1. Which extraocular muscle does eye abduction?
2. Which muscle does eye adduction?
3. Which muscle moves eye upwards?
4. Which muscle moves eye downwards?
5. Which muscle moves eye up and out?
6. Which muscle moves eye down and out?

Answer 8

1. Lateral rectus
2. Medial rectus
3. Superior rectus
4. Inferior rectus
5. Superior oblique
6. Inferior oblique

Question 9

What is the coloured part of the eye called?

Whats the function?

Answer 9

iris

To regulate the amount of light entering eyeball via the pupil

Question 10

What two types of muscles does the iris contain?

What else does the iris contain?

Answer 10

Circular muscle
Radial muscle

Melanocytes

Question 11

What determines eye colour?

Answer 11

Iris melanocyte conc high = brown eyes
Melanocyte conc moderate = green eyes
Melanocyte conc low = blue eyes

Question 12

Why is the pupil black?

Answer 12

Because you are visualising the heavily pigmented retina and choroid through the pupil and lens

Question 13

The Parasympathetic NS causes the pupil to what? Which muscle causes this?

The Sympathetic NS causes the pupil to what?

Answer 13

Constrict; circular muscle of iris

Dilate; radial muscle of iris

Question 14

What covers the eyeball except the cornea, gives the eyeball shape, protects the eye’s inner parts and serves as an attachment for the extraocular muscles?

Answer 14

Sclera - dense connective tissue

Question 15

What is the transparent curved part of the eye that covers the iris?

Answer 15

Cornea

Question 16

What are the 3 outer layers of the eyeball wall (superficial to deep)

Answer 16

Sclera (superficial)
Choroid
Retina (deep)

Question 17

What is the structure that is…
Attached to the inner surface of sclera, provides blood vessels to the retina, and has melanocytes to absorb stray light rays to avoid glare in the eyeball?

Answer 17

Choroid

Question 18

Why do albinos need to wear sunglasses or have trouble seeing?

Answer 18

Their choroid lacks melanin, so less stray light is absorbed in the choroid meaning they experience lots of glare in normal light

Question 19

What are the three layers of the eyeball?

Answer 19

1. Fibrous tunic - anterior cornea, posterior sclera
2. Vascular tunic (aka uvea)- iris, ciliary body, choroid
3. Retina (inner tunic)

Question 20

In the anterior portion of the vascular tunic the choroid becomes the…

Answer 20

Ciliary body

Question 21

Ciliary body is where ___ is formed

Answer 21

Ciliary body is where aqueous humour is formed

Question 22

Which cranial nerves supply which of the extraocular muscles?

Answer 22

CN III (superior/inferior/medial rectus, inferior oblique)
CN IV (superior oblique)
CN VI (lateral rectus)

Question 23

What is the structure that is the innermost layer of the eyeball, and is the beginning of the visual pathway?

Answer 23

Retina

Question 24

How does the lens adapt to near and far vision?

Answer 24

Lens is attached to cilliary muscles which contract or relax, altering the shape of the lens to adjust to near/far vision

Question 25

The optic (CN II) nerve exits the eyeball at the...

Answer 25

Optic disc

Question 26

What 3 structures pass through the optic disc?

Answer 26

CN II Central retinal artery Central retinal vein

Question 27

The 2 layers of the retina and their functions are...

Answer 27

Pigmented disc - deeper layer, contains melanin to absorb stray light rays to reduce glare Neural disc - more superficial, contains photoreceptors to process visual data -> sends nerve impulses across axons of CN II

Question 28

2 types of photoreceptors are called...

Answer 28

Rods (120 million) Cones (6 million)

Question 29

Function of rods and cones?

Answer 29

Rods - stimulated by dim light, do not process colour vision (therefore can only see in black/grey/white in the dark) Cones - stimulated by bright light, produce colour vision, 3 types of cones (blue, green and red depending on which colour of light they process)

Question 30

Loss of cones function can lead to...

Answer 30

Legal blindness

Question 31

What is the blind spot, and why is it called a blind spot?

Answer 31

Optic disc is the blind spot as it contains no photoreceptors Therefore cannot see any images that strike the blind spot

Question 32

The centre of the posterior portion of the retina is called the...

Answer 32

Macula

Question 33

The central depression of the macula, which contains only cones is called the.. Why is this structure significant?

Answer 33

Fovea It is the area of highest visual acuity (Reason why you move your eyes to see something, in order to make the image land non the fovea)

Question 34

The structure that helps focus images on the retina is called...

Answer 34

Lens

Question 35

The lens divides the inside of the eyeball into what 2 areas?

Answer 35

Anterior cavity (consists of anterior chamber and posterior chamber) Vitreous chamber

Question 36

1. Anterior chamber is between what two structures? 2. Posterior chamber is between what two structures?

Answer 36

1. Between cornea and the iris 2. Behind the iris and in front of lens

Question 37

What is the name of the fluid that is in the anterior cavity, nourishes the lens + cornea and is continually flowing?

Answer 37

Aqueous humour

Question 38

Describe the path of flow of aqueous humour?

Answer 38

Secreted out of ciliary body Enters posterior chamber Flows through pupil into anterior chamber Drains into trabecular meshwork and into canal of Schlemm Goes into blood

Question 39

The fluid inside the vitreous chamber that holds the retina flush against the choroid, and removes debris is called...

Answer 39

Vitreous body

Question 40

Debris in the vitreous body that casts shadows over the retina create...

Answer 40

Floaters

Question 41

Intraocular pressure is mainly formed by...

Answer 41

Aqueous humour (and vitreous body to a lesser extent)

Question 42

Normal IOP is what?

Answer 42

16mmHg