Cranial Nerves 4 - Herring

Question 1

Only composed of special sensory fibers for vision

Answer 1

CN II

Question 2

1st order cell bodies for vision of CN II = ____________ of the inner layer of the eyeball

Answer 2

Retinal ganglion cells

Question 3

Right and left optic nerves unite in the cranial cavity to form the

Answer 3

optic chiasm

Question 4

Some central processes of CN II, cross to the other side (decussate); others do not = this forms the ___________

Answer 4

optic tracts

Question 5

Optic tracts of CN II continue to 2nd-order cell
bodies in the ___________ of
the thalamus (primary pathway) and SYNAPSE here as well

Answer 5

lateral geniculate nucleus

Question 6

Axons from the 2nd order cell bodies of CN II project to the _________ which is for getting visual stimulus back to the occipital lobe

Answer 6

occipital cortex

Question 7

Lesions of CN II present with a __________ of visual field defects

Answer 7

RANGE

We can have complete blindness from one or both eyes

Loss of only a portion of
the visual field in each eye
* Due to the mix of
some fibers crossing
and others not
crossing at the optic
chiasm

Question 8

Each cranial nerve reflex will have a ________ limb & a _________ limb

Answer 8

sensory ; motor

Question 9

For the most part, 2nd order sensory neurons of CN II project to the __________ limb

Answer 9

motor

Question 10

Regarding pupillary light reflex, sensory CN II senses

Answer 10

light

Question 11

Regarding pupillary light reflex, CN III is _______ and sends parasympathetic to the _________ muscle

Answer 11

motor ; constrictor pupillae muscle

Question 12

What is the smallest cranial nerve

Answer 12

CN IV

Question 13

Where are the somatic motor LMNs of CN IV located

Answer 13

trochlear nucleus

Question 14

Axons of LMNs of CN IV decussate within the

Answer 14

brainstem

Question 15

Axons of LMNs of CN IV decussate within the brainstem then exit on its ___________ surface which is the ONLY CN TO DO SO

Answer 15

dorsal

Question 16

Axons from the right trochlear nucleus form the ______ trochlear nerve

Answer 16

left

Question 17

What muscle is the peripheral target of CN IV

Answer 17

superior oblique muscle

Question 18

Regarding a lesion of CN IV, someone would be unable to look ________ when the pupil (eye) is adducted

Answer 18

down

Results in diplopia when both eyes (pupils) are looking down in the medial position (going
down stairs, reading)

Question 19

CN IV nerve lesion =

Answer 19

ipsilateral pupil presentation

Question 20

CN IV - Trochlear nucleus lesion =

Answer 20

contralateral pupil presentation

Question 21

Where are the LMNs of CN VI

Answer 21

Abducens nucleus

Question 22

What muscle is the peripheral target of CN VI

Answer 22

lateral rectus muscle

Question 23

Lesion of CN VI

Answer 23

Unable to ABDUCT the eye during clinical (“H-pattern”) testing

Results in diplopia when looking toward the affected side

Question 24

regarding a lesion to CN VI or left abducens nucleus, when a patient is asked to look to the left, what happens?

Answer 24

The patient’s left eye stays straight and the patient’s right eye looks left (double vision)

Question 25

regarding a lesion to CN VI or left abducens nucleus, when a patient is asked to look to the right, what happens?

Answer 25

both eyes look to the right (normal vision) because it's the left lateral rectus muscle that is damaged which is not used when looking to the right

Question 26

What is the primary cranial nerve for somatic motor innervation to the extra-ocular muscles & levator palpebrae superioris ****Except lateral rectus muscle (CN VI) and superior oblique (CN IV)****

Answer 26

CN III

Question 27

CN III has ____________ fibers to 2 of the 3 intrinsic muscles of the eye

Answer 27

Preganglionic parasympathetic

Question 28

Regarding somatic motor for CN III, where are the LMNs

Answer 28

oculomotor nucleus

Question 29

axons of LMNs of CN III form the _______ nerve

Answer 29

oculomotor nerve

Question 30

Where are the preGPS cell bodies of CN III located

Answer 30

Edinger-Westphal (accessory oculomotor) nucleus

Question 31

Where are the postganglionic parasympathetic cell bodies of CN III located

Answer 31

Ciliary ganglion

Question 32

Postganglionic parasympathetic fibers (axons) of CN III hitch a ride on a branch of CN V, which branch?

Answer 32

V1

Question 33

What are the 4 peripheral targets of CN III

Answer 33

Extraocular muscules Levator palpebrae superioris Sphincter pupillae ciliary muscles (lens)

Question 34

Lesion to CN III - the eye (pupil) has what 3 symptoms in the anatomical position (when patient attempts to look straight ahead):

Answer 34

Dilated pupil Ptosis (droopiness) of upper eyelid Pupil is directed “down & out” (resulting in diplopia) *** this is because we have lost 4 of the 6 muscles ***

Question 35

What is the primary cranial nerve for somatic sensory (pain, temperature, proprioception, & touch) innervation from the head

Answer 35

CN V

Question 36

CN V is somatic motor to what 2 muscles

Answer 36

muscles of mastication pharyngeal arch 1 muscles

Question 37

Regarding somatic sensory for CN V, the 1st order cell bodies for touch, pain, & temp are located in the

Answer 37

trigeminal ganglion

Question 38

The peripheral processes of CN V form 3 divisions, what are they

Answer 38

CN V1 CN V2 CN V3

Question 39

Which branch of CN V is somatic motor

Answer 39

CN V3 (mandibular)

Question 40

Central processes forming the trigeminal nerve project to different nuclei (2nd order cell bodies) - what are they?

Answer 40

Main / chief / principal nucleus Spinal trigeminal nucleus

Question 41

Discriminative touch of CN V goes to what nucleus

Answer 41

Main / chief / principal nucleus

Question 42

Pain and temperature for CN V goes to what nucleus

Answer 42

Spinal trigeminal nucleus

Question 43

For CN V, 2nd order cell bodies primarily send their axons to 3rd order cell bodies located in the

Answer 43

VPM of the thalamus

Question 44

For CN V, 3rd order cell bodies project to the inferolateral portion of the

Answer 44

postcentral gyrus

Question 45

For CN V, where are the 1st order cell bodies for proprioception

Answer 45

Mesencephalic nucleus

Question 46

For somatic motor of CN V, where are the UMNs located

Answer 46

Cell bodies located in the precentral gyrus

Question 47

For CN V somatic motor, UMNs axons project BILATERALLY through the _________ tract

Answer 47

corticonuclear / corticobulbar

Question 48

The somatic motor LMNs of CN V are located in what nucleus

Answer 48

trigeminal motor nucleus

Question 49

The axons of LMNs of CN V contribute to CN V and follow what branch of CN V

Answer 49

mandibular (CN V3)

Question 50

What are the sensory from (pain, temp, touch) peripheral targets of CN V1

Answer 50

Skin at & superior to the eyes Eyeball (including cornea) ** basically skin of the forehead and eyeball **

Question 51

Lesion of CN V1 =

Answer 51

Decreased (or abnormal) sensations of pain, temperature, & touch from area of distribution ** lose sensory from forehead and eyeball **

Question 52

Peripheral targets of V3 = Sensory (pain, temp, touch) from

Answer 52

Skin along the region of the mandible Anterior 2/3rd tongue External ear

Question 53

Peripheral targets of V3 = Somatic motor to what 2 muscles

Answer 53

muscles of mastication pharyngeal arch 1 muscles

Question 54

CN V3 passes through _________ to reach __________ ganglion

Answer 54

foramen ovale trigeminal

Question 55

Sensory lesion to CN V3

Answer 55

Decreased (or abnormal) sensations of pain, temperature, & touch from area of distribution ** mandible and anterior 2/3 tongue **

Question 56

Motor lesion to CN V3

Answer 56

Deviation of mandible to side of the lesion during mouth opening ** lose motor to ipsilateral muscles of mastication **

Question 57

Sensory corneal reflex is from what CN

Answer 57

V1 (somatic sensory from eyeball) ** this is to close eyelid/blink **

Question 58

Motor corneal reflex is from what CN

Answer 58

CN VII (somatic motor to orbicularis oculi & visceral motor parasympathetic to lacrimal gland for tear production)

Question 59

Signs & Symptoms of impacted CN V1 & CN V2 from Cavernous Sinus Thrombosis

Answer 59

sensory deficits for forehead, eyeball, and cheek

Question 60

Regarding Sympathetic Pathway to the Head - where are the preganglionic sympathetic cell bodies

Answer 60

T1 - T4

Question 61

Regarding Sympathetic Pathway to the Head - where are the postganglionic sympathetic cell bodies

Answer 61

Superior Cervical Ganglion

Question 62

Postganglionic sympathetic fibers from the superior cervical ganglion form

Answer 62

cephalic arterial rami

Question 63

After postGS fibers form cephalic arterial rami, they reach their target organs by forming a plexuses, but to now get to the EYE, they follow what artery

Answer 63

ophthalmic artery

Question 64

If we lost sympathetics in the head, what would we see

Answer 64

Flushed face due to vasodilation as we have lost VASOCONSTRICTION from the smooth muscle of arteries No more sweating because we have lost innervation to our sweat glands Dry mouth because we have lost innervation to our salivary glands Constricted pupil because we have lost innervation to the dilator pupillae muscle Ptosis because we have lost innervation the superior tarsal muscle BUT we still have the levator palpebrae muscle so it's only slight ptosis

Question 65

Signs/symptoms of Oculosympathetic Palsy / Horner’s Syndrome

Answer 65

Slight ptosis of the upper eyelid Constricted pupil Vasodilation Decreased sweating

Question 66

Central processes of what cell bodies form CN II (optic nerve)

Answer 66

retinal ganglion cells

Question 67

if sensory CN II is damaged, we will have no ____________

Answer 67

constriction

Question 68

if right side motor CN III is damaged, what will we see

Answer 68

nothing will happen on the right side but we will have the expected response on the left side

Question 69

what can we expect to see if we accidentally impair CN II during a dental injection

Answer 69

temporary complete or partial blindness

Question 70

the axons of the right abducens nucleus forms the _____ abducens nerve

Answer 70

right

Question 71

if you damage CN III as it travels between the brainstem and superior orbital fissure, you damage what 2 fibers?

Answer 71

preGPS fibers somatic motor fibers

Question 72

Cavernous Sinus Thrombosis can impact what CNs?

Answer 72

3, 4, 6, V1 and V2

Question 73

What 3 signs/symptoms can you expect to see with cavernous sinus thrombosis

Answer 73

Fixed pupil (can't move because we lost all the nerves innervating the muscles to move the eye) Pupil unresponsive to light changes (due to loss of both parasympathetic innervation (CN III) and sympathetic innervation (traveling on ICA) Ptosis of the upper eyelid (because lost innervation to it)

Question 74

What signs/symptoms can we expect to see from a misplaced dental injection to CN III?

Answer 74

Ptosis of upper eyelid (because we lost innervation to levator palpebrae superioris) Pupil in down and out position at rest (because we lost innervation to 4 out of the 6 muscles) Can't do H pattern

Question 75

Proprioception of CN V goes to what nucleus

Answer 75

Mesencephalic nucleus