Lesson 8: Vision (& Smell)

Question 1

What is the pathway of olfactory information?

Answer 1

Cells in the olfactory epithelium
Olfactory bulb’s mitral cells
Olfactory tract - may cross in the medial olfactory stria
Temporal lobes - primary olfactory cortex

Question 2

What is the pathway of reflex activity, compared to conscious information, for vision? Why is this important?

Answer 2

Conscious info: retina to optic chiasm to optic tract to LGB
Reflex: from optic tract to superior colliculus.
If damage occurs after the optic tract, reflexes may still be present

Question 3

What vision is present in a lesion to the optic nerve?

Answer 3

Monocular blindness

Question 4

What is present in optic chiasm damage?

Answer 4

Bitemporal hemianopia

Question 5

One half of the optic chiasm is injured before decussation - what happens

Answer 5

Nasal hemianopia

Question 6

Injury to the optic tract or the lateral geniculate body - how does vision seem?

Answer 6

Contralateral homonymous hemianopia

Question 7

Injury to upper/lower optic raditiation

Answer 7

contralateral homonymous superior/inferior (opposite) quadrantanopia

Question 8

What is macular sparing? Why does it occur?

Answer 8

A lesion in the PCA may occur, but the macula is spared due to irrigation from the MCA

Question 9

What is hypermetropia?

Answer 9

Far-sighted: focal point is behind the retina

Convex lens: puts focal point at the retina

Question 10

What is myopia?

Answer 10

Near-sighted: Focal point is in front of the retina

Concave lens: adds focal length

Question 11

What is astigmatism?

Answer 11

Refractive error due to irregular shape of cornea or lens

Combined cylindrical and spherical lens

Question 12

What are the 3 main types of color vision, and which cone is missing with each?

Answer 12

Protanomaly: no red
Deuteranomaly: no green
Tritanomaly: no blue

Question 13

What are the three ocular nerves?

Answer 13

Oculomotor, trochlear and abducens

Question 14

What are the three aspects of accomodation of distance in vision?

Answer 14

Ocular convergence
Pupillary constriction
Lens thickening

Question 15

What two structures are responsible for coordination of eye muscles?

Answer 15

The medial longitudinal fasciculus and the pontine paramedian reticular formation

Question 16

What disease targets MLF?

Answer 16

MS - it commonly dymyelinates

Question 17

What is the MLF connected to?

Answer 17

The vestibular nuclei

Question 18

What movement is the superior rectus responsible for?

Answer 18

Eyeball upward

Question 19

What movements is the medial rectus responsible for?

Answer 19

Eyeball inward

Question 20

Inferior rectus movements?

Answer 20

Eyeball down

Question 21

Inferior oblique movements?

Answer 21

Up and out

Question 22

Superior oblique movements?

Answer 22

Eye down and in

Question 23

Levator palpebrae superior muscle eye movements? What two aspects does it have?

Answer 23

Lifts upper eyelid
Voluntary muscles - via the oculomotor nerve
Smooth muscles - via the sympathic nerves

Question 24

What does sympathetic nerve loss result in, regarding the levator palpebrae superior muscle?

Answer 24

Horner’s syndrome - constricted pupil, ipsilaterally dry red face

Question 25

What does damage to the voluntary muscle result in, regarding the levator palpebrae superior muscle?

Answer 25

oculomotor nerve palsy

Question 26

Why is pupil constriction so vulnerable to compression?

Answer 26

It is the parasympathetic portion of the oculomotor nerve, and thus is on the outside and in between the PCA and the superior cerebellar artery

Question 27

What is the pathway to pupil constriction, from light to muscles?

Answer 27

Light to the optic nerve, to the prectal nucleus bilaterally To the Edinger-Westphal nucleus bilaterally To the oculomotor nerve To the ciliary ganglion, to the constrictor pupillae muscle

Question 28

What 3 nerve pathways are involved in pupil constriction?

Answer 28

Optic nerve for info in, oculomotor nerves (both) for info out

Question 29

What is the difference between and indirect and a direct response in pupil constriction?

Answer 29

Direct response: eye being tested constricts | Indirect: other eye constricts

Question 30

What's the difference between the accommodation reflex and pupil constriction?

Answer 30

Accommodation: conscious Pupil: automatic

Question 31

What is the pathway of the accommodation reflex (3 parts)?

Answer 31

Signal to the occipital cortex to the frontal eye fields, to the LGB, to the Edinger-Westphal nucleus, to the ciliary ganglion: for constrictor pupillae muscle (pupil constriction) and to the ciliary muscle (lens focusing) Fibers to the oculomotor nucleus - innervate the medial rectus muscles (eye convergence)

Question 32

Where is the nuclei for the oculomotor nerve? What is its pathway to the ventral brainstem?

Answer 32

in the upper tegmentum | Through the red nucleus and the basis pedunculi to the ventral brainstem

Question 33

What muscles does the oculomotor nerve innervate?

Answer 33

The superior, medial and inferior rectus The inferior oblique The levator palpebrae superior

Question 34

What are the two nuclei of the oculomotor nerve?

Answer 34

The somatic motor nucleus - extrinsic ocular muscles | The Edinger-Westphal nucleus: visceral motor nucleus

Question 35

What are the symptoms of trauma to the oculomotor nerve? (3)

Answer 35

Dilated pupils, eyes directed outward, diplopia

Question 36

Where does the trochlear nerve exit?

Answer 36

The posterior surface of the brainstem

Question 37

Where is the nucleus of the trochlear nerve?

Answer 37

In the periaqueductal gray matter in the midbrain

Question 38

What muscle does the trochlear nerve innervate?

Answer 38

The superior oblique

Question 39

What does trauma with the trochlear nerve ressemble (1)?

Answer 39

Diplopia when looking down

Question 40

Where is the nucleus of the abducens, and what does it pass through?

Answer 40

In the upper tegmentum of the pons Through the pontine tegmentum and the corticospinal tract To the pontomedullary junction

Question 41

What muscle does the abducens nerve innervate?

Answer 41

The lateral rectus

Question 42

What does a lesion in the abducens nerve ressemble?

Answer 42

The eye directed in

Question 43

How is the pupillary light reflex tested? What type of patient can be tested?

Answer 43

They must be conscious Optic nerve damage: no response in either eye Oculomotor nerve damage: no response in one eye - side of damage