Visual System Flashcards Preview

Medicine, Year 2, Block 12 (Neurological, Neuromuscular, and MSK Diseases) > Visual System > Flashcards

Flashcards in Visual System Deck (47):
1

How does sensory information from the eye travel to the Primary visual cortex? What is its route

Eye -> Optic nerve -> Optic chiasm -> Optic tract -> Lateral geniculate nucleus -> Optic radiation -> Primary visual cortex

2

Where is the primary visual cortex located? What Broadmann's area is it?

Occipital lobe, Brodmann's area 17, 18, 19

3

If a patient experiences a visual field loss which is homonymous (same side in both eyes), what does this suggest?

The lesion has occured posterior to the optic chiasm

4

Lesions occuring at the optic chiasm would lead to what type of partial blindness?

Heteronymous hemianopia (loss of vision in opposite fields of each eye)

5

Complete blindness in one visual field (left or right) would suggest a lesion were?

Optic nerve

6

What are the three main layers of the eye?

- Fibrous later (outermost)
- Vascular layer (middle)
- Neural layer (inner)

7

What two structures comprise the Fibrous layer (outer layer) of the eye?

Cornea and sclera

8

What three structures comprise the Vascular layer (middle layer) of the eye?

Iris, cilliary body and choroid

9

What one structure comprises the Neural layer (inner layer) of the eye?

Retina

10

What is the centre part of the retina called?

Fovea (highest resolution of vision, highest density of neurones)

11

What are the two main functions of eye movements?

Gaze stabilisation
Gaze shifting

12

Which muscle closes the eyelid?

Levator Palpebrae Superioris (LPS)

13

What are the 6 extrinsic muscles of the eye

Superior Oblique
Inferior Oblique
Medial Rectus
Lateral Rectus
Superior Rectus
Inferior Rectus

14

What is the main function of the Medial Rectus muscle?

Adduction of eye

15

What is the main function of the Lateral Rectus muscle?

Abduction of eye

16

What is the main function of the Inferior Rectus muscle?

Depression of eye

17

What is the main function of the Superior Rectus muscle?

Elevation of eye

18

What is the main function of the Superior Oblique muscle?

Intorsion of eye

19

What is the main function of the Inferior Oblique muscle?

Extortion of eye

20

Cranial Nerve III (Oculomotor) innervates what Extrinsic eye muscles?

Medial Rectus
Inferior Rectus
Superior Rectus
Inferior Oblique

21

Cranial Nerve IV (Trochlear) innervates what Extrinstic eye muscle?

Superior Oblique (SO4)

22

Cranial Nerve VI (Abducens) innervates what Extrinstic eye muscle?

Lateral Rectus (LR6)

23

Which part of the brain controls eye movements?

Frontal Eye Field (FEF)

24

Which part of the brain controls planning of eye movements?

Supplementary Eye Field (SEF)

25

Which part of the brain is involved in maintaining visual attention?

Posterior Parietal Cortex

26

What is the role of Supplementary Eye Field (SEF)?

Planning of eye movements

27

What is the role of Posterior Parietal Cortex?

Maintaining visual attention

28

What is the role of Superior Colliculus with respect to eyes?

Orientation to object in the visual field

29

What is Anisocoria?

Unequal size of pupils in eyes

30

Pupil constriction is also known as..? Is the iris sphincter active or relaxed?

Miosis, sphincter active

31

Pupil dilation is also known as..? Is the iris sphincter active or relaxed?

Mydriasis, sphincter relaxed

32

Miosis and Mydriasis is under sympathetic or parasympathic control?

Miosis = Parasympathetic
Mydriasis = Sympathetic

33

The accomodation reflex is under what control? Sympathetic or parasympthatic?

Parasympathetic control

34

What are Cataracts?

Clouding of lens caused by compaction and protein deposition

35

What are risk factors for Cataracts?

Aging, trauma, diabetes, smoking, UVB light, genetic (congenital cataracts)

36

What is the anterior chamber filled with?

Aqueous humour

37

What is the role of Cilliary epithelium of the Ciliary body in the eye?

Production of Aqueous humour for the Anterior and Posterior Chamber

38

How is the Aqueous humour drained from the eye?

Out of the lens, through pupil, into anterior chamber. The drain through trabecular meshwork and then Schlemm's canal and out of the eye

39

What are risk factors for Glaucoma's?

Raised intraocular pressure (normal = 12-22)
Hypertension
Long-term steroid use
Severe myopia (-6.00)

40

What is the most common type of Glaucoma? What is it caused by? Is it acute or chronic?

Open-angle Glaucoma, caused by blockage of Trabecular meshwork. It is chronic

41

What is closed-angle Glaucoma caused by?

Caused by raised intra-ocular pressure which bows the iris and closes the anterior chamber. It is an acute medical emergency

42

What are some treatment options for Glaucoma? 4 groups

- Beta blockers
- Alpha2 adrenoceptor agonists
- Carbonic anhydrase inhibitors
- Miotics (muscarinic agonists)

43

What is the mechanism of action for Acetazolamide?

Carbonic anhydrase inhibitor, preventing Sodium reabsorption and thus allowing water secretion and reduction of Intraocular pressure

44

What is the main blood supply to the eye?

Choroid and choriocapillaries (outer retina)
Central retinal artery and vein (inner retina)

45

Is the fovea vascular or avascular?

Avascular

46

Red/green colour blindness particularly affects which gender? Why?

Red-green colour blindness, because it is X-linked

47

What are the two cell types in the Lateral genicular nucleus? What do they detect?

Magnocellular (detects light / dark)
Parvocellular (detects colour)