Exam 3: Visual System

Question 1

What does CN 3 innervate? Where is the nucleus?

Answer 1

Dorsal, ventral, and medial recti, and ventral oblique

Midbrain

Question 2

What does CN 4 innervate? Where is the nucleus?

Answer 2

Dorsal oblique

Midbrain

Question 3

What does CN 6 innervate? Where is the nucleus?

Answer 3

Retractor bulbi and lateral rectus

Brainstem

Question 4

How are conjugate eye movements coordinated?

Answer 4

By the medial longitudinal fasciculus

Question 5

What is strabismus? What are some causes?

Answer 5

Abnormal position of eyes

Neurologic or mechanical issues

Question 6

What are some causes of upper eyelid drooping (CN and muscles)?

Answer 6

CN 7: frontalis, levator anguli
CN 3: Levator palpebrae superioris
Sympathetic: Muller’s muscles

Question 7

What is the grown up term for upper eyelid drooping?

Answer 7

Ptosis

Question 8

What is the sensory innervation to the eyelid?

Answer 8

CN 5: opthalmic branch to the medial side

CN 5: maxillary branch to the lateral side

Question 9

What is the motor innervation to close the eyelid? Through what muscle?

Answer 9

CN 7

Orbicularis oculi

Question 10

What causes neuroparalytic keratoconjunctivitis sicca (KCS)?

Answer 10

CN 7 paralysis

Question 11

What cause neurotrophic keratitis?

Answer 11

CN 5 issues

Question 12

What does the corneal reflex test?

Answer 12

CN 5 and 6

Question 13

What does the palpebral reflex test?

Answer 13

CN 5 and 7

Question 14

What does the menace response test?

Answer 14

CN 2 and 7

Question 15

What are the photoreceptors of the retina?

Answer 15

Rods and cones

Question 16

Which photoreceptor of the retina works best in low light?

Answer 16

Rods (motion)

Question 17

Which photoreceptor of the retina works best in light?

Answer 17

Cones (color)

Question 18

Is the optic nerve a nerve or tract?

Answer 18

Tract

Question 19

Axons from the right visual field hit the ______ retina of the right eye and the ______ retina of the left eye to course through the _______ nucleus and the left occipital lobe.

Answer 19

Medial
Lateral
Lateral geniculate

Question 20

How much decussation occurs at the chiasm of people?

Answer 20

50%

Question 21

How much decussation occurs at the chiasm of birds?

Answer 21

100%

Question 22

How much decussation occurs at the chiasm of dogs?

Answer 22

75%

Question 23

How much decussation occurs at the chiasm of cats?

Answer 23

65%

Question 24

How much decussation occurs at the chiasm of farm animals?

Answer 24

75-80%

Question 25

What percent of fibers branch off the optic tract to influence pupillary light reflexes? Where are they going?

Answer 25

20% | Pretectal nucleus

Question 26

Will a disease of the retina cause vision deficits? PLR deficits?

Answer 26

Yes | Yes

Question 27

Will a disease of CN 2 cause vision deficits? PLR deficits?

Answer 27

Yes | Yes

Question 28

Will a disease of the optic chiasm cause vision deficits? PLR deficits?

Answer 28

Yes | Yes

Question 29

Will a disease of the LGN cause vision deficits? PLR deficits?

Answer 29

Yes | No

Question 30

Will a disease of PSANS nucleus of CN 3 cause vision deficits? PLR deficits?

Answer 30

No | Yes

Question 31

Will a disease of the occipital lobe of the cerebrum cause vision deficits? PLR deficits?

Answer 31

Yes | No

Question 32

Will a disease of CN 3 cause vision deficits? PLR deficits?

Answer 32

No | Yes

Question 33

Will a disease of the ciliary ganglion cause vision deficits? PLR deficits?

Answer 33

No | Yes

Question 34

Which ANS causes miosis? Mydriasis?

Answer 34

PSANS | SANS

Question 35

If you have good PLRs, does it mean you are visual?

Answer 35

No

Question 36

What is it called if you are blind with good PLR?

Answer 36

Cortical blindness

Question 37

Which is stronger in vet patients, direct or consensual PLR?

Answer 37

Direct

Question 38

When you shine a light in an eye and the eyelid blinks, what is that called? Can you say that the dog saw this light?

Answer 38

Dazzle reflex | No, but it lets you know that the optic nerve is intact

Question 39

If a pupil only constricts when light is shown into the opposite eye and is otherwise dilated all the time, where is the lesion?

Answer 39

Optic nerve

Question 40

Are TV shows correct when they freak out over "fixed and dilated" or "blown" pupils because this means a worse prognosis?

Answer 40

Yes

Question 41

What ganglion does the PSANS and SANS synapse on when traveling to the eye?

Answer 41

Cranial cervical

Question 42

What are the 4 clinical signs of lack of sympathetic tone to the eye?

Answer 42

Ptosis, enopthalmos, 3rd eyelid elevation, and miosis

Question 43

What muscles are being affected when there is a lack of sympathetic tone to the eye?

Answer 43

Ptosis: Enopthalmos 3rd eyelid elevation: Muller's muscles Miosis: ciliary muscles

Question 44

What do horses do that is different from other species with Horner's syndrome?

Answer 44

Sweating

Question 45

If you dim the lights in a room with a patient with anisocoria and the anisocoria worsens, is it PSANS or SANS issues causing the problem?

Answer 45

PSANS

Question 46

What is the most common thing that you might call Horner's that has many of the same signs as Horner's, but is not Horner's? What area is affected with this disease?

Answer 46

Internal and external ophthalmoplegia (mydratic) | Cavernus sinus

Question 47

What other nerves can be affected with a lesion in the cavernus sinus?

Answer 47

3, 4 , 5o, 6

Question 48

What drug can you give to cause pupil dilation and pupil constriction in a denervated pupil showing hypersensitivity?

Answer 48

Phenylephrine- dilate- symphatomimetic Pilocarpine- constrict- parasympathomimetic Atropine dilates eye