visual motor systems

Question 1

frontal eye field is a

Answer 1

PRE-MOTOR area, and is brodman areas 6 and 8 (depends on textbook)

Question 2

frontal eye fields receive target location from__ and project to___

Answer 2

• visual association cortex

- project to horizontal and vertical gaze centers of superior colliculus

Question 3

3 types of eye movemtnts that direct targets to the fovea?

Answer 3

• SACCADES=> rapid mvmt toward new targets (conjugate)
• SMOOTH PURSUIT=>slower mvmts that follow moving targets (conjugate)
• VERGENCE=> mvmts that adjust the eyes toward near and far objects (disconjugate)

Question 4

vestibulo-ocular reflex fxn

Answer 4

compensate for ACCELLERATION

aka–to keep things on your fovea –“foveation”

Question 5

optokinetic reflex fxn

Answer 5

compensates for mvmt of the entire visual field

aka–holds images STEADY during sustained head rotation

Question 6

pupillary light reflex fxn

Answer 6

maintains retinal illumination (4 neuron chain with ciliary ganglion and SHORT ciliary nerves)

Question 7

blink reflex fxn

Answer 7

protects the eye

Question 8

M1 (area 4)

Answer 8

random mvmts

Question 9

SM (area 6)

Answer 9

planned mvmts

Question 10

nuclei in the pons that have to do with visual system

Answer 10

• PPRF,
• abducens,
• MLF

Question 11

nuclei in the midbrain that have to do with the visual system

Answer 11

• MLF,
• occulomotor nucleus,
• trochlear nucleus,
• nuclei of Cajal and riMLF (vertical eye mvmts)

Question 12

two kinds of eye movement pathways

Answer 12

• nuclear and infranuclear pathways ==> brainstem nuclei and peripheral parts of CNIII, IV, VI
• supranuclear pathways ==> brainstem and forebrain circuits

Question 13

what are frontal eye fields for in eye movements

Answer 13

• remembered movements,
• scanning for areas of interest
• suppressing uninteresting things

Question 14

superior colliculus involvement in eye movements

Answer 14

• reflexive ORIENTATING. this spot has a map of your visual field so that if you see something interesting, your eye can accurately direct the fovea to that location

Question 15

what are the only two muscles that do NOT pull the eye at a WEIRD angle

Answer 15

• lateral rectus

- medial rectus

Question 16

what muscles and CN do you use for STRAIGHT and UPWARD gaze

Answer 16

• superior oblique (CN IV)

- superior rectus (CN III)

Question 17

Hering’s law

Answer 17

during conjugate eye mvmts, the YOKED muscle pair receives EQUAL innervation so the eyes move TOGETHER

Question 18

course of CNIII

Answer 18

• lateral wall of cavernous sinus (topmost nerve)
• receives nn from carotid plexus and V1
• enters s. orbital fissure THRU annulus
• DIVIDES to sup. and inf.

Question 19

course of CNIV

Answer 19

• lateral wall of cavernous sinus below CNIII
• crosses III, enters s. orbital fissure THRU annulus
• has communications with CAVERNOUS plexus and V1

Question 20

course of abducens nerve

Answer 20

• WITHIN cavernous sinus, lateral and inferior to ICA
• enters s. orbital fissure THRU annulus
• has communications with CAVERNOUS plexus and V1

Question 21

horizontal gaze center

Answer 21

frontal eye fields and superior colliculus.

BUT. thats NOT the only function of these two things. they can do all the mvmts

Question 22

three kinds of neurons in PPRF

Answer 22

excitatory burst => to abducens nucleus
inhibitory burst => to other abducens nucleus
omnipause neurons => allow your eyes to pause

Question 23

visual deficit if you have demeylination in ventral pons

Answer 23

ipsilateral abducens nerve palsy

Question 24

superior tarsal muscle
Innervation?
syndrome?

Answer 24

sypathetic fibers
horners syndrome. if the lesion is in the spinal cord or the superiro cervical ganglion, its full blown. if its after the ganglion, you ususally don’t have anhydrosis

Question 25

internuclear neurons

Answer 25

for CONJUGATE eye movement for MLF

Question 26

lesion of R abducens NERVE

Answer 26

R abducens nerve palsy. (ONLY R eye can't look R)

Question 27

lesion of R abducens NUCLEAR lesion

Answer 27

R lateral gaze palsy (the nucleus projects to TWO places, so NEITHER eye can go R)

Question 28

lesion of R PPRF

Answer 28

PPRF is abducens nucleus. R lateral gaze palsy

Question 29

lesion of L MLF

Answer 29

L internuclear ophthalmoplegia (can look L, but when you look R, the R eye gets nystagmus, and L eye can't do it) affects VI and contralateral III

Question 30

lesion of L MLF plus the L abducens nucleus

Answer 30

you wipe out 1 and a half eye movements. "one and a half syndrome" (you can only look R in the R eye, but you get nystagmus in it)

Question 31

vertical gaze centers

Answer 31

midbrain, close to occulomotor nucleus (riMLF and Cajal)

Question 32

what parts of cerebellum are involved in these eye movements

Answer 32

fastigial nucleus, flocculus

Question 33

if you have a pineal tumor, it presses on DORSAL MIDBRAIN. what will you see? (haha or not see)

Answer 33

- impaired vertical gaze - large irregular pupils that don't respond to light - eyelid abnormalities - impaired convergence

Question 34

frontal eye fields project to?

Answer 34

- horizontal gaze center, - superior colliculus - vertical gaze center

Question 35

superior colliculus UPPER layer info

Answer 35

input from the visual system for visual space | aka "WHERE is the info coming from"

Question 36

superior colliculus LOWER layers

Answer 36

receive info FROM upper layers. the lower part does the MOTOR movements, and project to GAZE centers

Question 37

smooth pursuit firing pattern?

Answer 37

its GRADED. aka you do NOT have bursts. its GRADUAL

Question 38

smooth pursuit input from?

Answer 38

CBellum more than superior colliculus | **remember that vestibuloCBellum goes thru juxtarestofirm body to vestibular nuclei and then to the motor nuclei

Question 39

NEAR response triad?

Answer 39

- eyes CONVERGE via action of medial recti - lens ROUNDS UP increasing refractive power - pupil CONSTRICTS (meiosis)

Question 40

where does VERGENCE come from

Answer 40

MIDBRAIN!!! - supraoculomotor area (SOA) - not well known, but it obviously has to involve CNIII

Question 41

occulomotor channel

Answer 41

supplementary eye fields - VA, - MD

Question 42

lesion of parietal cortex affecting vision

Answer 42

related to SPATIAL information - problems with where stream... SUPRAMARGINAL and ANGULAR gyri - problems with saccades - problems reaching for things in space - "Simultagnosia" problems multitasking eye objects

Question 43

what do NBME exams like to do

Answer 43

put in stupid charts of nerve impulses for things like nystgmus

Question 44

always remember what about nystagmus

Answer 44

ALWAYS named for the FAST phase