Cranial Nerve III, IV, and VI

Question 1

What happens to the eyes as you lateral flex head

Answer 1

The eyes rotate

Question 2

what cranial nerves control eye muscles involved in movment

Answer 2

Oculomotor III
Trochlear IV
Abducens VI

Question 3

What is the most common symptom of damage to these nerves

Answer 3

Double vision

Question 4

What nerve constricts the pupil

Answer 4

Oculomotor

Question 5

How many intrinsic ocular muscles are there

Answer 5

3

Question 6

How many extraocular muscles are there

Answer 6

6

Question 7

What is the only cranial nerve to exit the brainstem dorsally

Answer 7

Trochlear

Question 8

What component of the oculomotor nerve innervates the iris sphincter and ciliary muscle

Answer 8

Parasympathetic component

Question 9

What does the iris sphincter do

Answer 9

Contracts to constrict the pupil

Question 10

What does the ciliary muscle contracting do to the lens

Answer 10

Causes the lens to become convex or fat

Question 11

What does the ciliary muscle control

Answer 11

Accommodation of the lens

Question 12

What is the radial pupillary dilator muscle innervated by

Answer 12

The ascending cervical sympathetic system

Question 13

What does the radial pupillary dilator do

Answer 13

Dilates pupil

Question 14

What does the ciliary muscle relaxing do to the lens

Answer 14

Causes the lens to flatten out

Question 15

When viewing a distant object what does the lens look like

Answer 15

The lens is flat to allow the light to bend to the retina

Question 16

When viewing a near object what does the lens look like

Answer 16

The lens is convex or fat to allow the light to be bent even more to hit the retina

Question 17

How is light coming from far objects oriented

Answer 17

Parallel

Question 18

How is light coming from near objects oriented

Answer 18

Straight but diverging lines

Question 19

What are the 3 antagonistic pairs of extraocular muscles

Answer 19

1. Lateral and medial recti
2. Superior and inferior recti
3. Superior and inferior obliques

Question 20

What 3 axes does movement occur in

Answer 20

Horizontal, vertical, and torsional

Question 21

What is torsional movement

Answer 21

Twisting movements that bring the top of the eye toward the nose or away from the nose

Question 22

What extraocular muscles does the oculomotor nerve control (4)

Answer 22

1. Medial rectus
2. Inferior rectus
3. Superior rectus
4. Inferior oblique

Question 23

What extraocular muscle does the trochlear nerve control

Answer 23

Superior oblique

Question 24

What extraocular muscle does the abducens nerve control

Answer 24

Lateral rectus

Question 25

Where is the oculomotor nucleus

Answer 25

In the midbrain at the level of the mesencephalic reticular formation (superior colliculus and red nucleus)

Question 26

Where is the trochlear nucleus

Answer 26

Slightly caudal to the oculomotor nucleus

Question 27

Where is the abducens nucleus

Answer 27

In the pons at the level of the paramedian pontine reticular formation, adjacent to the fasciculus of the facial nerve

Question 28

Where is the oculomotor nerve at risk of damage

Answer 28

When it travels between the superior cerebellar artery and in posterior cerebral artery

Question 29

Why is the oculomotor nerve at risk of damage passing through these vessels

Answer 29

If hemorrhage occurs the nerve can become compressed

Question 30

What nuclei travel within the oculomotor nucleus (4)

Answer 30

1. Dorsal nucleus (inferior rectus) 2. Intermediate nucleus (inferior oblique) 3. Medial nuclei 4. Ventral nucleus (medial rectus)

Question 31

What are the 2 nuclei that are part of the oculomotor nuclear complex but aren't within the oculomotor nucleus

Answer 31

1. Edinger-Westphal nucleus (parasympathetics) | 2. Central caudal nucleus (levator palpebrae superioris)

Question 32

What are the characteristic deficits of CN III damage (3)

Answer 32

1. Impairment of eye movements 2. Drooping of eyelids (ptosis) 3. Pupillary dilation

Question 33

What is effected when there is impairment of eye movements

Answer 33

Extraocular muscles

Question 34

What is effected when there is drooping of the eyelids

Answer 34

Levator palpebrae superioris

Question 35

What is effected when there is pupillary dilation

Answer 35

Iris sphincter muscle

Question 36

What side deficits occur due to trochlear nuclei lesions

Answer 36

Contralateral

Question 37

What does the abducens nucleus and fibers of the facial nerve form

Answer 37

The facial colliculus on the floor of the 4th ventricle

Question 38

Where do fascicles of CN VI travel and exit the brain stem

Answer 38

Ventrally at the pontomedullary junction

Question 39

True or False: | Once the abducens nerve exits the brain stem it travels a long distance to the lateral rectus

Answer 39

True

Question 40

What muscles control left and right motions of the eye

Answer 40

Lateral and medial recti

Question 41

What muscles control up and down motions of the eye

Answer 41

Superior and inferior recti and obliques

Question 42

What is the primary position of the eye

Answer 42

Straight ahead, body and head erect

Question 43

What are the 4 secondary positions of the eye

Answer 43

1. Adducted 2. Abducted 3. Elevated 4. Depressed

Question 44

What are the 4 tertiary positions of the eye

Answer 44

1. Gaze up right 2. Gaze up left 3. Gaze down right 4. Gaze down left

Question 45

What is intorsion

Answer 45

Top of the eye rotating towards the nose (counter clockwise)

Question 46

What is extorsion

Answer 46

Top of the eye rotating away from the nose (clockwise)

Question 47

What are the primary, secondary, and tertiary motions of the inferior rectus

Answer 47

Primary: Depression Secondary: Extorsion Tertiary: Adduction

Question 48

What are the primary, secondary, and tertiary motions of the superior rectus

Answer 48

Primary: Elevation Secondary: Intorsion Tertiary: Adduction

Question 49

What are the primary, secondary, and tertiary motions of the superior oblique

Answer 49

Primary: Intorsion Secondary: Depression Tertiary: Abduction

Question 50

What are the primary, secondary, and tertiary motions of the inferior oblique

Answer 50

Primary: Extorsion Secondary: Elevation Tertiary: Abduction

Question 51

True or False: | Both eyes must move together

Answer 51

True

Question 52

True or False: | Muscles in both eyes are paired or yoked

Answer 52

True

Question 53

What does the muscles being paired or yoked cause

Answer 53

They both get similar stimulatory signals from the brain

Question 54

Whose law is both yoked muscles get similar stimulatory signals from the brain

Answer 54

Herring's Law

Question 55

True or False: | Muscles in one eye are in antagonist pairs

Answer 55

True

Question 56

Whose law is when one of a pair contracts the other must relax

Answer 56

Sherrington's Law

Question 57

What is supraduction also called

Answer 57

Elevation

Question 58

What is infraduction also called

Answer 58

Depression

Question 59

What is incycloduction also called

Answer 59

Incyclotorsion or intorsion

Question 60

What is excycloduction also called

Answer 60

Excyclotorsion or extorsion

Question 61

What are version movements

Answer 61

Movement of both eyes in the same direction

Question 62

What are the 6 version movements

Answer 62

1. Dextroversion 2. Levoversion 3. Supraversion 4. Infraversion 5. Dextrocycloversion 6. Levocycloversion

Question 63

What is dextroversion

Answer 63

Movement of both eyes to the right

Question 64

What is levoversion

Answer 64

Movement of both eyes to the left

Question 65

What is supraversion

Answer 65

Movement of both eyes upward

Question 66

What is infraversion

Answer 66

Movement of both eyes downward

Question 67

What is dextrocycloversion

Answer 67

Rotation of both upper cornea to the right

Question 68

What is levocycloversion

Answer 68

Rotation of both upper cornea to the left

Question 69

What are vergence movements

Answer 69

Movement of both eyes in opposite directions

Question 70

What are the 2 vergence movements

Answer 70

1. Convergence | 2. Divergence

Question 71

What is convergence

Answer 71

Adduction of both eyes towards midline

Question 72

What is divergence

Answer 72

Abduction of both eyes back to the primary position

Question 73

What muscles cause dextroversion and levoversion

Answer 73

Lateral and medial recti

Question 74

What muscles cause supraversion

Answer 74

Superior rectus and inferior oblique

Question 75

What muscles cause infraversion

Answer 75

Inferior rectus and superior oblique

Question 76

What muscles cause dextrocycloversion

Answer 76

Inferior oblique and inferior rectus of the right eye and superior oblique and superior rectus of the left eye

Question 77

What muscles cause levocycloversion

Answer 77

Superior oblique and superior rectus of the right eye and inferior oblique and inferior rectus of the left eye

Question 78

What does complete lesion to CN III cause (5)

Answer 78

1. Ptosis 2. External strabismus (exotropia or lazy eye) 3. Pupilo-dilation 4. Loss of accommodation and light reflex (constriction) 5. Diplopia (double vision)

Question 79

What causes the pupilo-dilation with complete lesion to CN III

Answer 79

Paralysis of pupillary sphincter

Question 80

What occurs with trochlear nerve palsy (2)

Answer 80

1. Hypertropia | 2. Extorsion

Question 81

What is hypertropia

Answer 81

Misalignment of the eyes superiorly (lazy eye)

Question 82

How can the hypertropia be compensated for

Answer 82

Tucking the chin and looking up slightly

Question 83

How can the extorsion be compensated for

Answer 83

Tilting the head away from the affected eye to the opposite shoulder

Question 84

True or False: | People with trochlear nerve palsy have difficulty descending stairs

Answer 84

True

Question 85

What does the abducens nerve send an interneuron to for innervation purposes

Answer 85

The contralateral medial rectus

Question 86

What does lesion to CN VI cause

Answer 86

Patient cannot turn ipsilateral eye laterally

Question 87

What deformity can be seen in a patient with CN VI damage

Answer 87

Internal strabismus

Question 88

Why does internal strabismus occur with CN VI damage

Answer 88

Because the lateral rectus is paralyzed and does not oppose the action of the medial rectus

Question 89

What pathway does the abducens nerve send information to the contralateral medial rectus

Answer 89

Medial Longitudinal Fasciculus pathway