4/5 Cranial nerves Flashcards
why do colds cause anosmia?
swellings indie nose prevents chemicals reaching olfactory receptora
which nerves pass through cribriform foramina?
olfactory
which nerves pass through optic canal?
optic
which nerves pass through superior orbital fissure?
oculomotor
trochlear
ophthalmic
abducens
which nerves pass through foramen ovale?
maxillary
which nerves pass through foramen rotundum?
mandibular
which nerves pass through internal acoustic meatus?
facial
vesgtibulocochlear
which nerves pass through jugular foramen?
glossopharyngeal
vagus
accessory
which nerves pass through hypoglossal canal?
hypoglossal
which lobe of cerebrum does olfactory that reach to perceive smell?
temporal
explain how lesions in different areas of visual pathway would cause different patterns of visual loss
retina/optic nerve: symptoms in affects eye
optic chasm/optic tract: both eyes due to mixing of fibres
pattern of visual loss in pituitary tumour
bitemporal hemianopia
arrangement of fibres of oculomotor nerve in pupil
somatic- central
parasympathetic- peripheral
which causes of oculomotor nerve lesions would spare the pupil?
microvascular ischaemia (i.e. blood supply issue)
which causes of oculomotor nerve lesions would involve the pupil? why?
-anuerysm
-head injury
-uncul herniation
involves autonomic (para) fibres
typical position of eye if trochlear nerve affected?
up and adducted
muscle supplied by abducens, and function
lateral rectus, abducts eyeball
test abducens nerve
inspect resting gaze
why would raised ICP most likely affect abducens out of CN 3,4, and 6?
-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
nerves involved in corneal reflex
Va -sensory, afferent
facial (orbicularis oculi)- motor, efferent
what is trigeminal neuralgia?
trigeminal nerve lesion die to aberrant blood vessel which compresses trigeminal nerve = sharp shooting pain in facial dermatome, headache
main sensory branches of Va
-frontal
-nasociliary: sensory to eye and skin over nose tip
Hutchinson’s sign
tip of nose vesicle affected by ophthalmic shingles = high risk of eye affected (nasociliary division) SITE THREATENING
most likely nerve affected in orbital blow out fracture
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
cause of dry mouth/eyes in facial nerve test
parasympathetic fibres affected
presentation of facial nerve lesion
WHOLE SIDE unilateral facial droop
maybe altered taste, dry mouth, can’t cry
causes of facial nerve issues
-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
Ramsay hunt syndrome
shingles, painful vesicles around external ear and unilateral facial droop
how does facial nerve emerge through skull base
stylomastoid foramen
3 intra petrous branches of facial nerve
-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))
how to tell between stroke or facial nerve lesion?
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
presentation of vesticulocochlear pathology
hearing loss
dizziness
vertigo
tinnitus
causes of vesticulocochlear pathology
-vestibular schwannoma
-basal skull fracture
presentation of glossopharyngeal pathology
-difficulty swallowing
presentation of vagus pathology
-difficulty swallowing
-weak cough
-speech difficulty/voice change
causes of vagus pathology
-RLN branch- thyroid pathology, surgery
-cartoid sheath pathology/surgery
-posterior cranial fossa tumours
-medulla infacrct
causes of glossopharyngeal pathology
-cartoid sheath pathology/surgery
-posterior cranial fossa tumours
-medulla infacrct
cause of hypoglossal pathology
-upper carotid sheath/ int/ext afrotid arteries surgery or poatholgy
-posterior cranial fossa tumours
-medulla infarct
-motor neurone disease
