Neuro cranial nerves Flashcards
Olfactory nerve function
olfaction
optic n function
vision
oculomotor nerve innervates…? what is their function
medial rectus, inferior rectus, superior rectus, inferior oblique > MOST EYE MOVEMENTS
palpebral muscles > HOLDS EYELIDS OPEN
ciliary muscles > PUPIL CONSTRICTION and ACCOMODATION
trochlear nerve innervates…? what is function
S4: superor obllique - down and out eye movement
trigeminal nerve innervates…? what is function
Sensation to face + corneal reflex
sensation anterior 2/3 of tongue
muscles of mastication
abducens nerve innervates…? what is function
L6: lateral rectus
OUT eye movement
facial nerve innervates…? what is function
facial muscles > facial movement
stapedius> controls acoustics of hearing (damage leads to HYPERACUSIS)
taste to anterior 2/3 of tongue
vestibulocochlear nerve innervates…? what is function
balance
hearng
glossopharyngeal nerve innervates…? what is function
poost 1/3 of tongue (taste+ sensation)
AND gag reflex
vagus nerve innervates…? what is function
sensation and motor to pharynx and laynx
include swallowing and speech
accessory nerve innervates…? what is function
SCM, trapezius
hypoglossal nerve innervates…? what is function
tongue muscles > tongue movement
what dermatome are the nipples
T4
what dermatome is the umbilicus
T10
CNIII palsy presentation
DOWN and OUT fixed eye gaze
ptosis (unable to open eye)
fixed dilated pupil (if PNS fibres also affected)
causes of CN3 palsy
stroke (posterior cerebral artery)
MS
basal skull fracture
What are causes of ptosis
Unilateral:
- Horner’s
- CN3 palsy
Bilateral:
- Myasthenia gravis
- Myotonic dystrophy
- congenital absence of muscles
Either: infection, inflammation, tumour
What is Horner’s syndrome, and what general pathophysiology is it caused by
CAUSED BY DAMAGE to SYMPATHETIC TRYNK
TRIAD OF:
- miosis (constricted pupil)
- ptosis
- facial anhydrosis
what can cause Horner’s syndrome
Vascular (carotid dissection, brainstem stroke)
Infection (pneumonia of lung apex)
Neoplasm (incl Pancoast tumour)
Idiopathic
Causes of Ptosis
nerve: (unilateral) CN3 palsy, Horner’s
NMJ: MG (bilateral)
muscle: myotonic dystrophy
How does pupil size vary between CN3 palsy and Horner’s
CN3: dilated
Horner’s: constricted
What is pupil like in MG
normal
how does CN4 palsy present
unable to turn eye down and out + diplopia
How does C5 palsy present
Loss of sensation to face (location depends on whether it is V1,2,3)
Absent corneal reflex (V1)
Muscle of mastication weakness (V3)
How does CN6 palsy present
inability to abduct eye
how doesC7 palsy present
Bell’s Palsy
are cranial nerves UMN or LMN
They are LMN
They synapse with their UMN at the brainstem nuclei
so what type of lesion is Bell’s palsy
LMN lesion
sx of Bell’s palsy
- ipsilateral paralysis of face incl forehead
- inability to close eyes
- hyperacusis (due to stapediius paralysis)
- metallic taste in mouth
- decrease in lacrimation
How is an UMN lesion different to Bell’s palsy?
UMN lesion will be FOREHEAD SPARING
because forehead has dual UMN innervation
What are causes of Bell’s palsy
Infective (otitis media, choleastatoma, VIRAL: HSV/CMV/EBV)
Neoplasm or trauma
How do you manage Bell’s palsy
Oral Pred 10 days
consider acyclovir
What are causes of UMN lesion facial droop
stroke
tumour
haematoma
What is Ramsay Hunt syndrome
unilateral LMN facial palsy due to HERPES ZOSTER reactivation
How does Ramsay Hunt syndrome present
severe ear pain, ipsilateral vertigo, hyperacusis, tintinnus
vescicles in ear, anterior 2/3 of tongue
CN8 palsy presentation
sensorineural hearing loss
nystagmys
vertigo
CN9 presentation
loss of gag reflex
CN10 pallsy presentation
ulna deviates AWAY from lesion side
dysphagia
CN12 palsy presentatin
atrophy of tongue + fasciculations
tongue deviates towards lesion
Lesions where in the motor pathway cause ONLY MOTOR SYMPTOMSS?
Muscle
NMJ
Anterior Horn
what is the difference in lesion location between spasticity and rigidity
spasticity: lesion in PYRAMIDAL TRACT (corticospinal)
rigidity: lesion in EXTRAPYRAMIDAL TRACT (rubrospinal / vestibulospinal)
How does spastity present
INCREASED TONE which is:
- velocity dependent
- greatest at the initial part of movement
How does rigidity present
INCREASED TONE which is
- NOT velocity dependent
- same resistance in all directions
which pathway supplies the limbs
the LATERAL corticospinal tract (where UMN decussates at medulla)
which pathway supplies trunk and axial muscles
the ANTERIOR corticospinal tract (where UMN do NOT decussate)
what causes MONOOCULAR VISION LOSS
Lesion in optic nerve (ipsilateral side)
what causes BITEMPORAL HEMIANOPIA
Lesion at optic chiams
What lesion causes a HOMONOMOUS HEMIANOPIA
CONTRALATERAL lesion of OPTIC TRACT or OPTIC RADIATIONS (beyond the optic chiasm)
What is a another name for. Relative Afferent Pupillary Defect
Marcus-Gunn pupil
what test allows you to detect RAPD
Swinging torch reflex
What occurss in RAPD
The afferent pathway of the eye is disripted
This leads to a non-responsive direct stimulation and a responsive indirect stimulation (light in the opposite eye)
what conditions cause RAPD
MS
Glaucoma
What is an Argyll Robertson pupil and what causes it
Small irregular pupils
present with accomodation reflex but without pupillary refleex
causes by diabetes or NEUROSYPHILIS (prostitute’s pulpil)
