Eye and Vision Physiology Flashcards Preview

Neurology > Eye and Vision Physiology > Flashcards

Flashcards in Eye and Vision Physiology Deck (47)
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1
Q

What are the three coats of the eye, from superficial to deep?

A

The fibrous coat, vascular coat and the sensory coat

2
Q

What are the component parts of the fibrous coat of the eye?

A

The cornea and the sclera

3
Q

What are the component parts of the vascular coat of the eye?

A

The iris, ciliary body and the choroid

4
Q

What are the component parts of the sensory coat of the eye?

A

The retina

5
Q

Which coats of the eye are complete and incomplete?

A

Complete- fibrous

Incomplete- vascular and sensory

6
Q

What structure does the anterior segment of the eye lie anterior to, and what is it filled with?

A

The lens

Filled with aqueous humor

7
Q

What structure does the posterior segment of the eye lie posterior to, and what is it filled with?

A

The lens

Filled with vitreous humor

8
Q

In what segment of the eye are the anterior and posterior chambers found, and what structure divides them?

A

Both found in anterior segment

Divided by iris

9
Q

Describe the drainage of the aqueous humor

A

The aqueous humor first drains to the trabecular meshwork in the angle of the anterior chamber, which drains to Schlemm’s canal, which drains to veins

10
Q

Name the quadrants of the eye

A

The upper nasal, lower nasal, upper temporal and lower temporal quadrants

11
Q

What kind of epithelium is present in the cornea?

A

Stratified, squamous, non-keratinised epithelium

12
Q

What is the basement membrane of the corneal epithelium called?

A

Bowman’s membrane

13
Q

How is transparency of the cornea maintained, histologically?

A

Regular arrangement of collagen
No blood vessels
Endothelial layer has a pump that keeps the aqueous humor out

14
Q

What is the site of most visual acuity in the eye called?

A

The fovea centralis

15
Q

What are the functions of the tear film?

A

Keeps cornea moist
Prevents drying
Washes away any particulate foreign bodies
Has antibodies and lysozymes to kill microbes
Smooths outer surface of cornea providing smooth surface for refraction.

16
Q

What nerve controls secretion of tears into the conjuctival sac?

A

Parasympathetic fibres of the facial nerve

17
Q

What structures of the eye are responsible for refraction of light?

A

The cornea, aqueous humor and the lens

18
Q

What is the visual field?

A

Everything that you can see with one eye (including periphery)

19
Q

Where do the nasal fibres of the optic nerve cross over?

A

At the optic chiasma

20
Q

Which fibres of the optic nerve cross over at the optic chiasma?

A

The nasal fibres

21
Q

Where do fibres from the optic tract synapse?

A

The lateral geniculate body of the thalamus

22
Q

Which half of the visual cortex sees which half of the visual field?

A

The right half of the visual cortex sees the left half of the visual field and vice versa

23
Q

What damage would be expected if one of the optic nerves is damaged?

A

Blindness in the ipsilateral eye

24
Q

What damage would be expected if the optic chiasma is disrupted in the middle?

A

Bitemporal hemianopia

25
Q

What damage would be expected if one of the optic tracts is damaged?

A

Contralateral homonymous hemianopia

26
Q

What damage would be expected if optic radiation is damaged?

A

Contralateral homonymous hemianopia

27
Q

What is the action of the intrinsic muscles of the eye as a group?

A

Control pupil diameter and alter lens curvature

28
Q

What is the action of the extrinsic muscles of the eye as a group?

A

Movement of the eye

29
Q

What are the names of the six extrinsic occular muscles?

A
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus
Superior oblique
Inferior oblique
30
Q

Describe the innervation of the extrinsic muscles of the eye

A

Superior oblique- trochlear nerve
Lateral rectus- abducent nerve
All others- occulomotor nerve

31
Q

What are the names of the intrinsic muscles of the eye?

A

Ciliaris
Constrictor pupillae
Dilator pupillae

32
Q

Describe the transduction mechanism involved in vision

A

Trans-retinol is converted into cis-retinol in the retinal pigment epithelium, using up some vitamin A. Cis-retinol is then transported back to the rods and cones to form opsin. The cascade of reactions within the rods/cones causes a hyperpolarisation, which transmits an impulse and becomes an action potential in the optic nerve cell

33
Q

What is the conjuctiva?

A

A thin, vascular membrane that covers the inner surface of the eyelids and the sclera

34
Q

What is the cornea?

A

It is the anterior 1/6th of the fibrous coat of the eyeball, it is transparent and allows light rays to enter the eyeball

35
Q

What is the sclera?

A

The posterior 5/6s of fibrous coat, opaque and gives attachments to muscles but does not move the eye

36
Q

What is the function of the ciliary body?

A

Suspends the lens and produces aqueous humor

37
Q

What is the function of the choroid?

A

Supplies blood to out layers of retina

38
Q

What is the function of the iris?

A

Controls the diameter of the pupil

39
Q

Is the crystalline lens biconvex or biconcave?

A

Biconvex

40
Q

How is the crystalline lens connected to the ciliary body?

A

Through suspensory ligaments

41
Q

What is the function of the aqueous and vitreous humors?

A

Aqueous- helps maintain intraocular pressure

Vitreous- Cushions the retina

42
Q

How is the lacrimal gland innervated?

A

It receives parasympathetic innervation from the facial nerve

43
Q

Where do the lacrimal ducts open into?

A

The conjuctival sac

44
Q

How do tears drain from the eyes?

A

Through punctae on the medial sides of the eyelids, draining into the lacrimal sac, which drains to the nasolacrimal duct, which drains into the inferior meatus

45
Q

Describe the innervation of the intrinsic muslces of the eye

A

Ciliaris and constrictor pupillae- parasympathetic from third nerve
Dilator pupillae- sympathetic from plexus around blood vessels

46
Q

What artery supplies all the structures within the orbit?

A

The ophthalmic artery

47
Q

What veins drain the eye, and what do they drain into?

A

The superior and inferior ophthalmic veins, which drain into the cavernous sinus