EOMs and related topics Flashcards Preview

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Flashcards in EOMs and related topics Deck (44)
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1

How many EOMs are there?

Six EOMs per eye

2

How many cranial nerves have motor control of the EOMs?

Three cranial nerves per eye

3

Which cranial nerve innervates the medial rectus?

CN III Oculomotor Nerve

4

Which cranial nerve innervates the superior rectus?

CN III Oculomotor Nerve

5

Which cranial nerve innervates the inferior rectus?

CN III Oculomotor Nerve

6

Which cranial nerve innervates the inferior oblique?

CN III Oculomotor Nerve

7

Which cranial nerve innervates the levator palpebrae superioris?

CN III Oculomotor Nerve

8

Which cranial nerve innervates the superior oblique?

CN IV Trochlear Nerve

9

Which cranial nerve innervates the leteral rectus?

CN VI Abducens Nerve

10

Which eye muscles are controlled by CN III?

Medial, superior, and inferior rectus, inferior oblique, and levator palpebral superioris

11

What are the three types of eye movements?

Versions, vergences, and ductions.

12

Define versions

Rotations of the two eyes such that their lines of sight move in the SAME direction

13

Define vergences

Rotations of the two eyes such that their lines of sight move in the OPPOSITE directions

14

What are the two types of versions?

saccadic and pursuit (smooth)

15

Saccadic movements are ____ and ____.

a. fast or slow
b smooth or jerky

a. fast
b. jerky

16

Moving eyes from one object to another requires which type of version?

Saccadic

17

Which kind of version are voluntary or triggered by the appearance of an object in the peripheral field?

Saccadic

18

When voluntarily shifting fixation from one point to another, as in reading, which type of version must you use?

Saccadic

19

Which part of the brain controls saccades?

The frontal lobe

20

What is the function of pursuits (smooth) eye movements?

Function is to maintain fixation on the object of interest (once it has been located by the saccadic system).

21

Which kind of version is triggered by movement of an object near the fovea (central vision)?

Pursuits

22

Pusuits movements are ____ and ____.

a. fast or slow
b smooth or jerky

a. slow
b. smooth

23

Which part of the brain controls pursuits?

The occipital lobe

24

What are the two types of vergence?

Convergence and divergence

25

During convergence, which muscles are working and which way do the eyes turn?

Medial rectus contracts in both eyes, pulling the eyes to the nose.

26

During divergence, which muscles are working and which way do the eyes turn?

Medial rectus relaxes and/or lateral rectus contracts OU, pulling the eyes out and away from the nose

27

Define duction

Rotation of one eye under monocular conditions

28

What are the two main types of duction

Abduction and adduction

29

Define abduction

Lateral (temporal) rotation of an eye; movement of the eye away from the nose

30

Define adduction

Medail (nasal) rotation of an eye; movement of the eye toward the nose

31

Define supraduction

Movement of an eye upward

32

Define infraduction

Movement of an eye downward

33

Define levoduction

Movement of an eye to the left

34

Define dextroduction

Movement of an eye to the right

35

Define yoked muscle pairs

Muscles of two eyes which simultaneously contract to turn the eyes equally in the same direction.

ex. right medial rectus and left lateral rectus contract simultaneously to move the gaze to the left

36

Sherrington’s Law of Reciprocal
Innervation

The CONTRACTION of each ocular muscle is accompanied by a simultaneous and proportional RELAXATION of its antagonist.

37

Sherrington's Law describes the signal sent by the brain to coordinate _____ pairs.

antagonistic

38

The right medial rectus and the right lateral rectus are antagonists; as one contracts, the other must relax. This is an example of _____ Law.

Sherrington's

39

Simplified version of Sherrington's Law

contraction = relaxation

Amount of CONTRACTION innervation given to a muscle must equal the amount of RELAXATION innervation given to its antagonist

40

Hering’s Law of Equal Innervation

Innervation to the muscle of one eye is equal to that in the other eye, resulting in movement of the two eyes that is equal and symmetrical

41

Heting's Law describes brain signals that coordinate which type of eye movements?

versions

42

Looking to the right requires equal innervation to the right lateral rectus and the lefter medial rectus. This is an example of _____ Law.

Hering's

43

____ Law states that the innervation to the yoke muscle in the non-fixating eye must equal the innervation to the corresponding agonist muscle in the fixating eye.

Hering's

44

Which tests are used to screen for EOM dysfunction?

H-pattern and O-pattern