Vision

Question 1

Palpebrae

Answer 1

Eyelids
Separated by the palpebral fissure
Meet at the middle and lateral angles

Question 2

Annular ring in the orbit

Answer 2

Origin of the 4 rectus muscles

Question 3

6 extrinsic eye muscles

Answer 3

Lateral and medial rectus
Superior and inferior rectus
Superior and inferior oblique

Question 4

Inferior oblique

Answer 4

Elevates eye and turns it laterally

Question 5

Superior oblique

Answer 5

Depresses eye and turns it laterally

Question 6

Fibrous layer

Answer 6

Most external layer of eyeball

Composed of 2 regions of CT

Question 7

Limbus

Answer 7

Junction between sclera and cornea

Responsible for regeneration of the cornea

Question 8

Scleral venous sinus

Answer 8

Allows aqueous humor to drain

Question 9

Vascular layer

Answer 9

Middle coat of eyeball

Composed of choroid, ciliary body and iris

Question 10

Choroid

Answer 10

Vascular, darkly pigmented membrane
Forms posterios 5/6 of vascular tunic
Brown colour from melanocytes
Prevents scattering of light rays in eye

Question 11

Ciliary body

Answer 11

Thickened ring of tissue which encircles the lens
Composed of ciliary muscle
Ciliary processes (posterior surface) and ciliary zonule (suspensory ligament)

Question 12

Iris

Answer 12

Visible coloured part of the eye
Attached to the ciliary body
Composed of smooth muscle

Question 13

Iris pigmentation

Answer 13

The only pigments are brown pigments
Blue eyed people have brown on the inside of the iris, but none on the outside
NO BLUE PIGMENT
We see blue because of refraction

Question 14

Pupil

Answer 14

Round central opening in iris
Sphincter pupillae muscle
Dilator pupillae muscle

Question 15

Pupillary light reflex

Answer 15

Protective response of pupil constriction when a bright light is flashed in the eye

Question 16

Parasympathetic vs Sympathetic effects on the pupil

Answer 16

PS: sphincter pupillae muscle contracts (inner), pupil size decreases
S: Dilator pupillae muscle contracts (outer), pupil size increases

Question 17

Retina

2 layers

Answer 17

Deepest tunic
Pigmented layer: single layer of melanocytes
Neural layer: sheet of nervous tissue

Question 18

3 tunics of the external walls of the eye

Answer 18

Fibrous layer
Vascular layer
Retina

Question 19

3 main types of neurons in the neural layer of the retina

Answer 19

Photoreceptor cells - signal bipolar cells
Bipolar cells - signal ganglion cells
Ganglion cells - axons from here run along surface of the retina - converge to form optic nerve

Question 20

Photoreceptors

Answer 20

2 main types: rods and cones
Considered neurons
Light particles modify the visual pigment and generate a nerve impulse
Vulnerable to damage by light or heat
Cannot regenerate if destroyed
Continuously renew and replace their outer segments

Question 21

Rods vs Cones

Answer 21

Rods: more sensitive to light (vision in dim settings)
Cones: operate best in bright light (enable high-acuity, color vision
They have both inner and outer segments (outer segments are receptor regions where light absorbing pigments are present)

Question 22

Regions of the Retina:

1. Ora serrata
2. Macula lutea
3. Fovea centralis
4. Optic disk

Answer 22

1. Neural layer ends at the posterior margin of the ciliary body, pigmented layer covers ciliary body and posterior surface of iris
2. Contains mostly cones
3. Contains only cones (highest visual acuity)
4. Blind spot

Question 23

2 sources the retina gets its blood from

Answer 23

1. Outer third of the retina (supplied by capillaries in the choroid)
2. Inner two thirds of the retina (supplied by central artery and vein of the retina)

Question 24

Vitreous humor

Answer 24

Found in the posterior segment of the eye
Clear, jellylike substance
Transmits light, supports posterior surface of the lens, helps maintain intraocular pressure

Question 25

Aqueous humor

Answer 25

Found in anterior segment of the eye
Renewed continuously 
Formed as a blood filtrate
Supplies nutrients to the lens and cornea
Produced by the ciliary body

Question 26

Lens

Answer 26

Thick, transparent, biconvex disc
Held in place by its ciliary zonule
Lens epithelium covers anterior surface of the lens
Lens fibers form the bulk of the lens (new fibers are continously added, so lens enlarged throughout life)

Question 27

Myopic eye

Answer 27

Nearsighted (cannot see distance)

The eyeball is too long and the focal point is in front of the retina

Question 28

Hyperopic eye

Answer 28

Farsighted (cannot see close)

Eyeball is too short and the focal point is behind the retina

Question 29

Tarsal plates

Answer 29

Connective tissue within the eyelids

Question 30

Lacrimal caruncle

Answer 30

Reddish elevation and medial canthi

Question 31

2 eye muscles that aren’t controlled by oculomotor nerve 3

Answer 31

Lateral rectus: abducens nerve (6)

Superior oblique: trochelar nerve (4)