8.04 eom part 2

Question 1

what can a nerve palsy be a sign of?

Answer 1

serious underlying health condition

Question 2

what sort of diseases present in the eom at first?

Answer 2

• myasthenia graves
• thyroid eye disease

Question 3

nystagmus

Answer 3

• involuntary eye movements
• can be result of ms/ vascular lesions in adults
• neurological conditions in children

Question 4

each eye is held in position and rotates under the influence of what?

Answer 4

the 6 extra ocular muscles
1. superior rectus
2. inferior rectus
3. medial rectus
4. lateral rectus
5. inferior oblique
6. superior oblique

Question 5

why are the 6 eom essential?

Answer 5

• only one part of retina has optimum visual acuity (fovea)
• need to be able to compensate for our head and body movements
• visual system is not good at processing moving images

Question 6

fick’s axes

Answer 6

1. vertical axis
2. transverse axis
3. sagittal axis

• these imaginary lines pass through the centre of rotation and they remain almost constant

Question 7

vertical axis of fick’s axes

Answer 7

• eyes rotate/turn in and out
• adduction
• abduction

Question 8

transverse axis of fick’s axes

Answer 8

• eyes turn up or down
• elevation
• depression

Question 9

saggital axis of fick’s axes

Answer 9

• intorsion: rotating the eye in towards the nose
• extorsion: rotates eyes away from nose

Question 10

one eye: ductions

Answer 10

1. ABduction: eye turns out
2. ADduction: eye turns in
3. SUPRAduction: elevation
4. INFRAduction: depression
5. INCYCLOduction: intorsion
6. EXCYCLOduction: extension

Question 11

two eyes: versions

Answer 11

• eyes move together in same direction (conjugate)
• to the left/right/ up/ down

Question 12

2 eyes: vergence

Answer 12

• eyes move together in opposite directions (disconjugate)
• CONvergence
• DIvergence

Question 13

tertiary gaze positions: oblique positions

Answer 13

1. up and out
2. up and in
3. down and out
4. down and in

Question 14

types of eye movements: gaze shifting

Answer 14

• major type of eye movement
• to keep the image of a visual target focused on the fovea when the target changes or moves
• use smooth pursuits of saccades for this

Question 15

types of eye movement: gaze stabilising

Answer 15

• used when the head moves or appears to move
• allows a reference point between you and the person, and your physical space
• use optokinetic, vestibular, visual fixation

Question 16

5 oculomotor subsystems

Answer 16

1. saccadic
2. smooth pursuit
3. vergence
4. vestibulo-ocular
5. optokinetic nystagmus

Question 17

saccadic oculomotor subsystems

Answer 17

• used to place an image on fovea (e.g when we read)
• reading is a series of saccades with a pause for fixation
• lateral / oblique/ vertical eye movements

Question 18

smooth pursuit oculomotor subsystems

Answer 18

• used to follow a moving object

Question 19

vergence oculomotor subsystem

Answer 19

gives bifocal fixation at different distances

Question 20

vestibule-ocular oculomotor subsystem

Answer 20

stabilises line of sight during head movement (by moving eyes in opposite direction to the way youre rotting you’re head)

Question 21

optokinetic nystagmus oculomotor subsystem

Answer 21

• eye movement response to large moving visual fields (head is still)
• e.g staring out of window in train

Question 22

ipsilateral

Answer 22

the same side

Question 23

contralateral

Answer 23

the opposite side

Question 24

agonist

Answer 24

muscle that produces the eye movement

Question 25

relaxation

Answer 25

muscle is relaxed and not under tension

Question 26

antagonist

Answer 26

muscle that opposes the agonist (one that produces the eye movement)

Question 27

contraction

Answer 27

muscle is actively pulling

Question 28

synergist

Answer 28

2 muscles in the same eye that cooperate to produce the same eye movement

Question 29

location of orbits

Answer 29

at an angle of 23 degrees

Question 29

yoked muscles

Answer 29

muscle in each eye that are responsible for turning eyes in a a given direction

Question 30

because orbits are at 23 degree angle what does this mean?

Answer 30

- only the medial and lateral rectus have got simple actions - medial rectus will adduct the eye - lateral rectus abducts the eye

Question 31

what doe the superior and inferior rectus have an angle of from the line of sight? what does this cause them to have?

Answer 31

- 23 degree angle from the line of sight - secondary and tertiary actions - not just elevation and depression

Question 32

what are the obliques at an angle of?

Answer 32

51 degrees giving secondary and tertiary actions

Question 33

if you want the superior rectus to act as an elevator where do you direct the eye?

Answer 33

ABDuct the eye by 23 degrees

Question 34

what to do if you want to isolate the inferior rectus to depress the eye?

Answer 34

abduct by 23 degrees and pull the eye down

Question 35

what to do if you want the inferior oblique to act as an elevator?

Answer 35

- adduct the eye by 51 degrees - if you wanted to depress the eye, its only the superior oblique that would be acting

Question 36

MUSCLE ACTIONS TABLE IN NTOES THAT YOU MUST MEMORISE

Answer 36

!!!!

Question 37

Sherrington's law of reciprocal innervation

Answer 37

- when a muscle contracts, its direct antagonist relaxes to an equal extend allowing smooth movement - so to abduct my eye, I have to contract my lateral rectus, but relax the medial rectus but the same amount

Question 38

elevation, what is working together?

Answer 38

- superior rectus and inferior oblique are contracting - so inferior rectus and super obliques need to relax

Question 39

depression, what's working together?

Answer 39

- inferior rectus and superior oblique contract - so the superior rectus and inferior obliques need to relax

Question 40

ABduction, what is happening? (eye turned out)

Answer 40

- lateral rectus is contractus - medial rectus is relaxing

Question 41

Adduction, what is happening? (eye turned in)

Answer 41

- medial rectus is contracting - lateral rectus is relaxing - superior and inferior rectus are working equally against each other to make sure eye doesn't shoot up or down

Question 42

how do the 2 eyes link together though?

Answer 42

- motor link for binocular vision to occur - Hering's law of equal innervation - states that when a nerve impulse is sent to a muscle causing it to contact, and equal impulse is sent to the contralateral synergist to maintain parallelism of the visual axis - contralateral = opposite eye - synergist = muscle that moves the eye in same direction

Question 43

for right eye to move to right what has to happen?

Answer 43

- right medial rectus relaxes - right lateral medial contracts

Question 44

if I want to move BOTH my eyes to the right?

Answer 44

- right lateral rectus contracts - right medial rectus relaxes - left medial rectus contracts - left lateral rectus relaxes

Question 45

if you want to look up and left?

Answer 45

use right inferior oblique and left superior rectus

Question 46

if you want to look down and right?

Answer 46

use right inferior rectus and left superior oblique

Question 47

if you are looking over to right what are you using?

Answer 47

- right lateral rectus - left medial rectus

Question 48

what are you using to look right and up?

Answer 48

-because the lateral rectus is abducted by 23 degrees - can only use right superior rectus and left inferior oblique

Question 48

if you look right and down what are you using?

Answer 48

- right inferior rectus - left superior oblique

Question 49

what do you use to look over to left with 2 eyes?

Answer 49

- left lateral rectus - right medial rectus

Question 50

what do you use to look left and up?

Answer 50

- because the right eye is now adducted by 51 degrees and left eye is abducted by 23 degrees - only using left superior rectus and right inferior oblique

Question 51

what do you use to look left and down?

Answer 51

- left inferior rectus - right superior oblique