Session 4- Cranial nerves I-VI

Question 1

role of cranial nerves

Answer 1

supply tissues and structures of head and neck region including special sense organs

Question 2

what is CN 1

Answer 2

olfactory special sense smell

Question 3

absence or reduced sense of smell

Answer 3

anosmia

hyposmia

Question 4

commonest cause of anosmia and other causes

Answer 4

upper resp tract infection
head/facial injury- impact
anterior cranial fossa tumours

Question 5

what is cranial nerve 2

Answer 5

optic special sense vision

Question 6

function of CN2

Answer 6

pupillary size and response to light
visual acuity - snellen chart and visual fields
opthalmoscopy

Question 7

describe the visual pathway

Answer 7

retinal ganglion cells

axons from optic nerve

exits back of orbit via optic canal

fibrres cross and merge at optic chiasm

Question 8

what communication is present to aid the visual reflexes

Answer 8

visual infor coming in from the optic nerve will have a communication into the brainstem from the optic tract and will help form part of the light reflex

Question 9

function of optic nerve

Answer 9

carries sensory fibres from the one eye

Question 10

optic chiasm

Answer 10

mixing of sensory fibres from right and left optic nerves

Question 11

optic tract

Answer 11

carries sensory information from part of the right eye and part of the left eye

Question 12

what is bilateral heminopia

Answer 12

pituitary tumours that compress teh optic chiasm cause bilateral visual symptoms

Question 13

cranial nerve topography

Answer 13

2 2 4 4 
2- brain-forebrain
2-midbrain
4-pons
4-medulla

Question 14

cranial nerve 3

Answer 14

oculomotor- motor and parasympathetic

Question 15

how do we determine if there any issues with cranial nerve 2

Answer 15

inspect the pupillary size and response to light

Question 16

what are the target tissues of the cranial nerve

3 from the midbrain

Answer 16

extra occular muscles (4 out of 6)
levator palpebrae superiosis
sphincter pupillae- in iris surrounds pupil

Question 17

how do we determine if there is something wrong with the third nerve

Answer 17

inspect the resting gaze 
could find
-ptosis
-abnormal positioning of eyes
-pupil may or may not be dilated

Question 18

what is teh main blood supply to the occulomotor nerve

Answer 18

vaso nervosum

Question 19

what are the secondary back up blood supply to the oculomotor nerve

Answer 19

pial blood vessels

Question 20

cranial nerve 4

Answer 20

trochlear - motor

Question 21

where does CN 1 orginate

Answer 21

forebrain

Question 22

CN 2 origination

Answer 22

extension of forebrain

Question 23

where does cranial nerve 3 come from

Answer 23

midbrain

Question 24

where does cranial nerve 4 orginate

Answer 24

midbrain

Question 25

target muscle of CN4

Answer 25

superior oblique muscle

Question 26

how do we determine if there is anything wrong with the 4th cranial nerve

Answer 26

inspect resting gaze and eye movements

Question 27

how would pathology of CN4 present

Answer 27

abnormal eye position | head tilt

Question 28

route of trochlear nerve

Answer 28

orginates from midbrain then travels through cavernous sinus then through superior orbital fissure into back of eye

Question 29

CN VI

Answer 29

ABDUCENS

Question 30

where does CN VI originate

Answer 30

pons

Question 31

target of CN VI

Answer 31

lateral rectus - moves eye laterally

Question 32

how do we determine if the abducens nerve is working

Answer 32

inspect resting gaze and eye movements

Question 33

route of abducens nerve

Answer 33

travel from pons and has a steep upwards route to the cavernous sinus and travels through the superior orbital fissure

Question 34

what is the consequence of the steep upwards route of the abducens nerve

Answer 34

makes it vulnerable when there is an increase in intracranial pressure it gets stretched

Question 35

route of the first cranial nerve

Answer 35

travels from nasal cavity through holes in ethmoid bone to the temporal lobe

Question 36

route of occulomotor nerve

Answer 36

travels from the midbrain in a spiral corkscrew way very closely to the tentorum cerebelli then through the cavernous sinus then enters the superior orbital fissure

Question 37

what is the common route of the cranial nerves supplying the eye muscles

Answer 37

exit brainstem- at slightly different levels pass through cavernous sinus enter into the orbit via the superior orbital fissure

Question 38

what are the cranial nerves that supply the eye muscles

Answer 38

occulomotor- 3rd abducens- 6th trochlear- 4th

Question 39

cranial nerve 5

Answer 39

trigeminal - motor and general sensory

Question 40

what does the 5th cranial nerve supply

Answer 40

branches have extensive distribution supplying skin of the face and scalp and deep structures of the face

Question 41

how do you determine if there is damage to the trigeminal nerve

Answer 41

light touch to the Va Vb and Vc dermatomes muscles of mastication corneal reflex- SENSORY (motor is by facial nerve through orbicularis oculi)

Question 42

route of the trigeminal nerve

Answer 42

the opthalmic and maxillary travel through the cavernous sinus however mandibular doesnt opthalmic-> cavernous sinus -> superior orbital fissure maxillary -> cavernous sinus -> foramen rotundum Mandibular -> foramen ovale

Question 43

what kind of nerve is CN I

Answer 43

special sense smell | sensory

Question 44

what kind of nerve is cranial nerve 2

Answer 44

special sense vision | optic

Question 45

what kind of nerve is the 3rd nerve

Answer 45

motor and parasympathetic | occulomotor

Question 46

what kind of nerve of CN 4

Answer 46

motor | trochlear

Question 47

what kind of nerve is the 6th nerve

Answer 47

motor abducens

Question 48

what kind of nerve is CNV

Answer 48

motor and general sensory | trigeminal