Special Senses Part 2 - The eye

Question 1

What are the 4 walls of the bony orbit?

Answer 1

Superior
Inferior
Lateral
Medial

Question 2

Label the parts of the bony orbit?

Answer 2

Question 3

What are the accessory structures of the eye?

Answer 3

Eyebrows
Eyelashes
Eyelids
Extrinsic muscles that move the eyeballs
Lacrimal apparatus

Question 4

Label the basic eye features?

Answer 4

Question 5

What is the process of the ‘tear system’ (lacrimal apparatus)?

Answer 5

Question 6

Identify the extraocular muscles?

Answer 6

Question 7

Identify the layers of the eyeball?

Answer 7

Question 8

What is the fibrous layer (fibrous tunic) of the eye & what does it contain?

Answer 8

–> Is the outer coat of the eyeball.
–> Contains anterior cornea & the posterior sclera.

Question 9

What is the function of the cornea and the sclera?

Answer 9

Cornea:
Transmits and refracts incoming light.

Sclera:
Supports eye shape and protects it.

Question 10

What is ‘conjunctiva’ and what surface does it cover?

Answer 10

It is an epithelial layer which covers the sclera.

Question 11

What is the vascular tunic?

Answer 11

–> The middle layer of the eyeball.
–> Composed of the choroid, ciliary body, and iris.

Question 12

What is the choroid?

Answer 12

A thin membrane that lines most of the internal surface of the sclera.

Question 13

What is the function of the choroid?

Answer 13

Supplies nourishment to the retina.

Question 14

What does the ciliary body consist of?

Answer 14

–> Consists of the ciliary processes (folds on the inner surface of the body whose capillaries secrete a aqueous humor fluid).
–> Consists the ciliary muscle (a smooth muscle that alters the shape of the lens for viewing objects close up or at a distance).

Question 15

What are the 2 functions of the lens?

Answer 15

1. A transparent structure that focuses light rays onto the retina.
2. Contains zonular fibers or suspensory ligaments which attach the lens to the ciliary muscle and hold the lens in position.

Question 16

What is the iris?

Answer 16

The coloured part of the eyeball.

Question 17

What does the iris contain?

Answer 17

It includes both sphincter circular smooth muscle fibers and dilator pupillae radial smooth muscle fibers.

Question 18

What is the function of the sphincter and dilator pupillae muscles?

Answer 18

They regulate the amount of light entering the pupil by decreasing or increasing the size of the pupil.

1. The sphincter pupillae reduces the pupil size.
2. The dilator pupillae increases the pupil size

Question 19

What happens to the pupil when there is bright versus low light?

Answer 19

Bright light -> pupillary constriction
Sphincter pupillae contracts (parasympathetic innervation).

Low light -> pupillary dilation
Dilator pupillae contracts (sympathetic innervation).

Question 20

What is the retina and its 2 layers?

Answer 20

–> Is the third and inner coat of the eyeball.
–> The neural layer and pigmented layer.

Question 21

What is the function of the retina?

Answer 21

Converts light that enters into your eye into electrical signals your optic nerve sends to your brain which creates the images you see.

Question 22

What is the function of the pigmented layer of the retina?

Answer 22

–> Absorbs extraneous light.
–> Provides vitamin A for photoreceptor cells.

Question 23

What is the function of the neural layer of the retina?

Answer 23

Detects incoming light rays, where the light rays are converted to nerve impulses and transmitted to the brain.

Question 24

Where are the fovea centralis of the retina located?

Answer 24

A small depression in the centre of the macula lutea (or yellow spot) in the exact centre of the retina.

Question 25

What is special about the fovea centralis of the retina?

Answer 25

It is the area of highest visual acuity or resolution (sharpness of vision) because of its high concentration of cones.

Question 26

How does information move from photoreceptors?

Answer 26

From photoreceptors, information flows to bipolar cells and then from bipolar cells to the ganglion cells.

Question 27

Why is the optic disc known as the blind spot of the eye?

Answer 27

Because the optic disc contains no rods or cones, we cannot see an image that strikes the blind spot.

Question 28

What does Ophthalmoscopy involve?

Answer 28

It visualises the posterior part or the fundus of the eye, which includes the retina, optic disc, choroid and blood vessels.

Question 29

What are the 2 segments of the eye?

Answer 29

The lens divides the interior of the eyeball into two cavities or segments:
1. Anterior segment (located anterior to the lens).
2. Posterior segment (located posterior to the lens).

Question 30

What is the fluid found in the anterior segment of the eye and what is its function?

Answer 30

Aqueous humor:
Helps maintain the shape of the eye and nourishes the lens and cornea, neither of which has blood vessels.

Question 31

What is the fluid/body found in the posterior segment of the eye and what is its function?

Answer 31

Vitreous body:
Helps prevent the eyeball from collapsing and holds the retina flush against the choroid.

Question 32

What is intraocular pressure and what is it produced by?

Answer 32

–> The pressure in the eye.
–> Produced mainly by the production and drainage of the aqueous humor.

Question 33

What is the function of intraocular pressure?

Answer 33

Maintains the shape of the eyeball and keeps the retina smoothly pressed against the choroid.

Question 34

Identify the order of the visual pathway?

Answer 34

Retina –> Optic nerve –> Optic chiasm –> Optic tract –> Thalamus –> Midbrain –> Projection fibres (optic radiation) –> Primary visual cortex of the occipital lobe.

Question 35

Label the structure of the eyeball?

Answer 35

Question 36

Label the structure of the eyeball?

Answer 36