the visual system

Question 1

Accessory structures of the eye

Answer 1

• eyelids
• eyelashes
• eyebrows
• lacrimal apparatus - tears
• extrinsic eye muscles

Question 2

Extrinsic eye muscles

Answer 2

• superior rectus
• interior rectus
• lateral rectus
• medial rectus
• superior oblique
• inferior rectus
  move the eyeball laterally, medially, superior and inferiorly.

Question 3

layers of the eyeball

Answer 3

• fibrous tunic
• vascular tunic
• retina

Question 4

fibrous tunic

Answer 4

• the sclera

- the cornea

Question 5

The sclera

Answer 5

• dense connective tissue
• gives shape and rigidity to the eyeball
• protects inner parts
• provides an attachment point for extrinsic muscles

Question 6

the function of the cornea

Answer 6

• curved and helps focus light onto the retina.

Question 7

Vascular tunic - middle layer

Answer 7

• the choroid
• ciliary body
• the iris

Question 8

the choroid

Answer 8

• the vascular tunic and lines the internal surface of the sclera
• provides nutrients for the retina and absorb stray light

Question 9

ciliary body

Answer 9

• capillaries that secrete aqueous humour (provide nutrients for the lens and cornea).

Question 10

ciliary muscle

Answer 10

alters the shape of the lens for near and far vision

Question 11

the function of the iris?

Answer 11

• between the cornea and the lens
• regulates the amount of light entering the eye through the pupil
  bright light = circular muscles contract
  dim light = radial muscles contact

Question 12

Layers of the retina

Answer 12

• The pigmented layer

- The neural layer

Question 13

the pigmented layer

Answer 13

• between the choroid and neural layer

- prevents reflection and scattering of light within the eyeball

Question 14

the neural layer

Answer 14

• an outgrowth of the brain
• processes visual information before sending it down the optic nerve.
  has 3 cell types
• photoreceptors, bipolar cell layer, the ganglion cell layer
  It’s layered so that light passes through the ganglion and the bipolar layer before reaching the photoreceptors

Question 15

Photoreceptors

Answer 15

Rods: allows to see a dim light
Cones: activated during bright light conditions (colour receptors).

Question 16

pathway of visual information

Answer 16

photoreceptors = bipolar cells = ganglion cells

- axons exit the eyeball through the optic disk and form the optic nerve.

Question 17

optic disk

Answer 17

no photoreceptors = blind spot

Question 18

central fovea

Answer 18

• has a small depression on the retina
• contains only cones
• contains bipolar cells and ganglion but doesn’t cover the cones
• highest visual activity

Question 19

the function of the lens

Answer 19

• helps focus on images onto the retina = accommodation
• far = flatter
• close = round

Question 20

optic chiasm

Answer 20

axons of the left and right optic nerve pass through it

Question 21

visual field

Answer 21

• help produce depth perception
• visual fields of both eyes overlap
• light rays from the nasal half of the visual field fall on the temporal the retina
• light rays on the temporal half of the visual field fall on the nasal half of the retina.

Question 22

pathway of visual information

Answer 22

optic nerve = optic chiasm = optic tract = thalamus = cerebral cortex