4/5 Cranial nerves

Question 1

why do colds cause anosmia?

Answer 1

swellings indie nose prevents chemicals reaching olfactory receptora

Question 2

which nerves pass through cribriform foramina?

Answer 2

olfactory

Question 3

which nerves pass through optic canal?

Answer 3

optic

Question 4

which nerves pass through superior orbital fissure?

Answer 4

oculomotor
trochlear
ophthalmic
abducens

Question 5

which nerves pass through foramen ovale?

Answer 5

maxillary

Question 6

which nerves pass through foramen rotundum?

Answer 6

mandibular

Question 7

which nerves pass through internal acoustic meatus?

Answer 7

facial
vesgtibulocochlear

Question 8

which nerves pass through jugular foramen?

Answer 8

glossopharyngeal
vagus
accessory

Question 9

which nerves pass through hypoglossal canal?

Answer 9

hypoglossal

Question 10

which lobe of cerebrum does olfactory that reach to perceive smell?

Answer 10

temporal

Question 11

explain how lesions in different areas of visual pathway would cause different patterns of visual loss

Answer 11

retina/optic nerve: symptoms in affects eye
optic chasm/optic tract: both eyes due to mixing of fibres

Question 12

pattern of visual loss in pituitary tumour

Answer 12

bitemporal hemianopia

Question 13

arrangement of fibres of oculomotor nerve in pupil

Answer 13

somatic- central
parasympathetic- peripheral

Question 14

which causes of oculomotor nerve lesions would spare the pupil?

Answer 14

microvascular ischaemia (i.e. blood supply issue)

Question 15

which causes of oculomotor nerve lesions would involve the pupil? why?

Answer 15

-anuerysm
-head injury
-uncul herniation

involves autonomic (para) fibres

Question 16

typical position of eye if trochlear nerve affected?

Answer 16

up and adducted

Question 17

muscle supplied by abducens, and function

Answer 17

lateral rectus, abducts eyeball

Question 18

test abducens nerve

Answer 18

inspect resting gaze

Question 19

why would raised ICP most likely affect abducens out of CN 3,4, and 6?

Answer 19

-its most susceptible to stretch as vertical route and fixed at brainstem exit, and fixed at entry to cavernous sinus
so downward displacement of brain from raised ICP stretches the anchored nerve

Question 20

nerves involved in corneal reflex

Answer 20

Va -sensory, afferent
facial (orbicularis oculi)- motor, efferent

Question 21

what is trigeminal neuralgia?

Answer 21

trigeminal nerve lesion die to aberrant blood vessel which compresses trigeminal nerve = sharp shooting pain in facial dermatome, headache

Question 22

main sensory branches of Va

Answer 22

-frontal
-nasociliary: sensory to eye and skin over nose tip

Question 23

Hutchinson’s sign

Answer 23

tip of nose vesicle affected by ophthalmic shingles = high risk of eye affected (nasociliary division) SITE THREATENING

Question 24

most likely nerve affected in orbital blow out fracture

Answer 24

infraoribtal nerve, as increased pressure in eye socket collapses floor of orbit and this nerve runs in floor

superior alveolar nerve affected too if there’s numbness of gums/upper teeth

Question 25

cause of dry mouth/eyes in facial nerve test

Answer 25

parasympathetic fibres affected

Question 26

presentation of facial nerve lesion

Answer 26

WHOLE SIDE unilateral facial droop maybe altered taste, dry mouth, can't cry

Question 27

causes of facial nerve issues

Answer 27

-internal acoustic meatus lesions -posterior cranial fossa tunours -basal skull fracture -middle ear disease -facial canal inflammation e.g. bells palsy, Ramsay hunt -parotid disease

Question 28

Ramsay hunt syndrome

Answer 28

shingles, painful vesicles around external ear and unilateral facial droop

Question 29

how does facial nerve emerge through skull base

Answer 29

stylomastoid foramen

Question 30

3 intra petrous branches of facial nerve

Answer 30

-nerve to stapedius (dampens vibration of stapes) -greater petrosal (para to lacrimal. nasal mucosal glands) -Chorda tympani (taste anterior 2/3, para to salivary except parotid))

Question 31

how to tell between stroke or facial nerve lesion?

Answer 31

stroke: upper half of contralateral face spared, forehead sparing, can close eye but can't smile. as ipsilateral cortex can back up facial nerve: whole side of ipsilateral face affected

Question 32

presentation of vesticulocochlear pathology

Answer 32

hearing loss dizziness vertigo tinnitus

Question 33

causes of vesticulocochlear pathology

Answer 33

-vestibular schwannoma -basal skull fracture

Question 34

presentation of glossopharyngeal pathology

Answer 34

-difficulty swallowing

Question 35

presentation of vagus pathology

Answer 35

-difficulty swallowing -weak cough -speech difficulty/voice change

Question 36

causes of vagus pathology

Answer 36

-RLN branch- thyroid pathology, surgery -cartoid sheath pathology/surgery -posterior cranial fossa tumours -medulla infacrct

Question 37

causes of glossopharyngeal pathology

Answer 37

-cartoid sheath pathology/surgery -posterior cranial fossa tumours -medulla infacrct

Question 38

cause of hypoglossal pathology

Answer 38

-upper carotid sheath/ int/ext afrotid arteries surgery or poatholgy -posterior cranial fossa tumours -medulla infarct -motor neurone disease