Congugate Eye mvmts

Question 1

Afferent corticomesencephalic fibres to the motor nuceus of CN III (3)

Answer 1

1. Bilateral corticomesencephalic fibres from frontal eye field (area 8)
2. Tectobulbar fibres (from sup colliculus for auto mvmt)
3. MLF

Question 2

Efferent connection of corticomesencephalic fibres

Answer 2

CN III

Question 3

When will you see a CNIII palsy and what will it cause

Answer 3

LMN type lesion

-down and out orientation of affected eye

Question 4

What mvmts will be affected in a CNIII palsy (right eye affected)

Answer 4

look down- kinda works as inf rectus impaired but sup oblique still good

look right- fine

loof left- will not be able to as medial rectus affected

look up- less mvmt

Question 5

afferent input of corticomesencephalic fibres to CN IV(3)

Answer 5

1. bilateral Corticomesencephalic fibres from frontal eye field (8)
2. Tectobulbar fibres (from inf coliculi for reflexive type mvmt)
3. MLF

Question 6

Output of corticomesencephalic fibres to CNIV

Answer 6

CNIV (sup ob)- ex. left rochlear nucleus is the the right trochlear nerve and supplies R SO

Question 7

Effect of CNIV palsy (3)

Answer 7

Head tilted slightly to healthy side (side of eye affected slightly elevated)

Afftected eye shoots up and in when looking left (if right eye affected)

affected eye cant look fully down and in

Question 8

afferent of corticomesencephslic fibres to CNVI abducens (3)

Answer 8

1. Bilateral corticomesencephalic fibres from Frontal eye field
2. Tectobulbar fibres
3. MLF

Question 9

Affect of CNVI palsy

Answer 9

affected eye will be slightly inward normally

Will not be able to look laterally on affected eye

Question 10

Input of MLF (3)

Answer 10

1. IL + CL medial vestibular nucleus (helps keep target in sight
2. Axons from CL PPRF (horizontal mvmt)
3. axons from CL interneyrons of motor nucleus CNVI to motor nucleus of CNIII (conection bw lat rectus and med rectus)

Question 11

Where is the center for saccadic and smooth pursuit

Answer 11

Saccadic- frontal eye field (area 8)

Smooth pursuit- Post parietal eye field

Question 12

What is the PPRF and the input to it

Answer 12

• dispacher for coordination of horizontal mvmt

1. CL frontal eye field
2. CL sup colliculus
3. IL vestibular nucleus

Question 13

Output of PPRF

Answer 13

Fires into IL abducens nucleus which sends info to IL lat rectus
-Also fires into interneurons in IL abducens nucleus which connects to CL oculomotor nuc through MLF for medil rectus

Overall will look right horizontally

Question 14

What is the function of the nucleus prepositus hypoglosi

Answer 14

key for maintaining horizontal gaze

Question 15

What happens in a stroke to the Frontal eye field (ex on left)

Answer 15

• Deviation of both eyes toward side of lesion
• Voluntary saccadic movement away from lesion cant be made (but involuntary can because sup colliculus still good)

-likely will also have CL hemiplegia of body

Question 16

What happens in a stroke to post parietal eye field

Answer 16

• impaired smooth pursuit movements away from the side of lesion
• voluntary saccades is not affected though and will compensate

Question 17

What is the affect of MLF deficit

Answer 17

Will affect abducens so affected MLF will make that side eye not be able to move in

Question 18

What is the center of vertical saccades and two main dispachers (+ function)

Answer 18

CL frontal eye field

Verticle saccades - RIN of MLF

Maintaining gaze- Interstial nuc of Cajal

Question 19

Circuitory of downwards saccades

Answer 19

RIN MLF has unilateral conection to occulomotor + trochlear nucleus

oculomotor goes to iL inf rectus
trochlear nerve crosses over to CL side for sup oblique

Question 20

Circuitory of upwards saccades

Answer 20

RIN MLF has bilateral connection to elavtors

Crosses over midline thru post commisure to inf oblqie
crosses over midline to sup recutus

Question 21

if there was a tumor in rostral midbrain what would be affected

Answer 21

paralysis of downwards gaze

Question 22

If there was somethig compressing the post commisure what would be affected

Answer 22

bilateral paraylsis of upward gaze