cranial nerves VII- XII Flashcards
what is CNVII
facial
which fibres in facial nerve
sensory motor and parasympathetic
where is nucleus of facial nerve
in the tegmentum of the pons
where is facial nerve
attached to brain stem at the pontomedullary junction
somatic motor function of facial nerve
muscle of facial expression
visceral motor function of facial nerve
lacrimal glands (tears), submandibular & sublingual salivary glands
function of facial nerve
role of upper and lower motor neurones in the control of facial muscles
what causes facial weakness
differentiation between upper and lower motor neurone
what are the 2 roots of the facial nerve
medial - motor fibres
lateral - sensory and parasympathetic fibres (the nervus intermedius )
course of facial nerve
complex course through the temporal bone
special sensation of facial nerve
taste buds of the anterior 2/3rds of the tongue
fibre types in facial nerve
special sensory - taste anterior 2/3 tongue
motor - muscles of facial expression
parasympathetic- lacrimal glad, submandibular and sublingual salivary glands
how many branches of facial nerve
within the parotid, the terminal part of the facial nerve divides into 5 branches
how to test special sensory facial nerve
ask about taste, test taste sensation , anterior 2/3 tongue
what is the course of facial nerve closely related to
the middle ear
how does the facial nerve exit the skull
via the internal acoustic meatus
how to test lacrimation
is the eye dry
what do corticobulbar fibres of the facial nerve provide
*Contralateral innervation of the lower face
* Bilateral innervation of the upper face
how to test motor function of facial nerve
observe the face at rest - weakness, asymmetry, sagging
look for flattening of the nasolabial folds and drooping of the lower
eyelids
test the muscles and 5 branches
ask patient to:
frown and raise eyebrows
screw up eyes tightly
puff out cheeks
smile
how to test sensory function of facial nerve
touch the lateral aspect of the tongue with a cocktail stick
(dipped in sugar, salt, or vinegar)
and ask the patient to identify the taste
what is facial weakness a sign of
that someone’s had a stroke
what does injury of the facial nerve lead to
facial weakness
what is bell’s palsy
an idiopathic condition - unknown cause
inflammation of the facial nerve
thought to be related to viral infection
will see dribbling out the side of mouth
what is the most common lesion of the facial nerve
bells palsy
what problems are caused by injury to facial nerve (5)
- bell’s palsy
- inflammation or tumour of parotid gland
- tumours
- middle ear infection
- fractures of the temporal lobe
describe motor cortex
part of it is dedicated to the upper face
part of it is dedicated to the lower face
the cell bodies of UMNS reside in the motor cortex
their axons travel to the facial motor nuclei in the pons
upper and lower motor neurones
the upper axons synapse with cell bodies of the lower neurones in the facial motor nuclei (pons)
axons of the umns for the upper and lower face cross the midline and synapse with the contra lateral fasciae motor nucleus
the facial motor nucleus also receives input from the ipsilateral motor cortex which controls the upper face
what is CNVIII
vestibulocochlear
is vestibulocochlear sensory or motor
sensory
function of vestibulocochlear nerve
conducts auditory and vestibular-related impulses from the organ of corti
(sound), semicircular canals, the utricle & the saccule (vestibular)
how does vestibulocochlear nerve exit the skill
via the internal acoustic meatus
how to test vestibulocochlear cochlear component
- crude testing - covering each ear and whispering into the opposite one
- rinne and webers tests
- audiometry (specialist equipment)
how to test vestibulocochlear nerve vestibular component
- observe patients balance, gait
- caloric testing
what is a sign of vestibular disfunction
Nystagmus ( rapid involuntary abnormal eye movements)
what are the 2 causes of deafness
- sound not getting to ear- (conductive deafness)
- problems with the nerves/organ of corti - (neurological deafness)
effects of damage to vestibulocochlear nerve
- Deafness
- Dizziness
- Nausea
- Loss of balance
- Nystagmus
causes of damage to vestibulocochlear nerve
- The vestibulocochlear nerve runs very close to the bone
- Is also very affected by surrounding tumours - if a tumour arises in
the internal acoustic meatus then this will press on the
vestibulocochlear & facial nerve - Skull fracture
- Toxic drug effects
- Ear infections
what is acoustic neuroma
tumour of vestibulocochlear nerve
benign
compresses the nerve
progresses to compress the facial nerve as they run together
what is CN IX
glossopharyngeal
which fibres in glossopharyngeal
sensory motor and parasympathetic
but motor is very minor
how does glossopharyngeal exit the skull
via the jugular foramen along with the vagus & accessory
where is glossopharyngeal
attached to the medulla via several small rootlets
motor function of glossopharyngeal
- Elevates the pharynx (motor to stylopharyngeus - swallowing & gag
reflex) - Secretion of PAROTID GLAND (salivary) - via parasympathetic
innervation
sensory function of glossopharyngeal
- Sensation from the external ear
- Posterior 1/3 rd of tongue - touch, pain & temperature
- Pharynx - touch, pain & temperature
- Eustachian tube - touch, pain & temperature
- Carotid sinus & body - baro & chemoreception
what is CN X
vagus nerve
which fibres in vagus
sensory, motor and parasympathetic
where is vagus
attached to medulla via several small rootlets
between the pyramid & inferior cerebellar peduncle
how does vagus nerve exit the skull
via the jugular foramen
functions of vagus nerve
- Taste - via posterior pharynx
- Swallowing - muscles of the pharynx & larynx ( EXCEPT the
stylopharyngeus (CN 9) - Cardiovascular & GI regulation
- Sensation of hunger
- Sensation of fullness
- Sensation to external ear
impact of vagus nerve on heart rate and blood pressure
causes a decreased heart rate & blood pressure when stimulated
how to examine glossopharyngeal and vagus nerves (3)
- Observe quality of patients voice
- Ask patient to say “Ah” and observe the elevation of the palate
- Absence of the gag reflex suggests a lesion in the glossopharyngeal or
vagus nerves
what is hoarseness of voice a sign of
vocal cord paralysis - caused by
compression or damage of the RECURRENT LARYNGEAL NERVE
(vagus derivative) which supplies all the intrinsic muscles of the larynx
(except the cricothyroid muscle)
what is nasal voice a sign of
paralysis of the palate
how to identify bilateral lesions of the vagus nerve
palate fails to rise
how to identify unilateral paralysis of the vagus nerve
both the palate and uvula deviate to the normal side AWAY from the lesion
what is CN XI
accessory
which fibres in accessory nerve
motor
what does accessory nerve supply
the sternocleidomastoid & trapezius muscles
where are cell bodies of accessory nerve
in the ventral horn of the upper 5 segments of the spinal cord
course of accessory nerve
sends fibres through the foramen magnum which then exits the skull via
the jugular foramen with vagus & glossopharyngeal
what does accessory nerve run in close proximity to
the internal jugular vein (which also exits the
jugular foramen)
what does injury to accessory nerve result in
paralysis of the sternocleidomastoid and trapezius muscles on the same side as the lesion
cranial part of accessory nerve
rootlets arise from the medulla
leaves via the jugular foremen by joining the vagus
spinal part of accessory nerve
from ventral horn spinal cord C1-C5
travels up through the foremen magnum
leaves again through the jugular foremen
innervates sternocleidomastoid and trapezius
how to test sternocleidomastoid of accessory nerve
ask patient to turn head against resistance -
paralysis is present is there is difficulty rotation head to the side
opposite to the lesion
how to test trapezius
ask patient to shrug the shoulders against resistance -
paralysis is present if there is an inability to shrug
what is CN XII
hypoglossoal
describe hypoglossal nerve
motor nerve > muscles of the tongue
arises from the medulla, leaves through the hypoglossal canal
is hypoglossal sensory or motor
motor
what does hypoglossal nerve supply
the extrinsic & intrinsic muscles of the tongue
where are cell bodies of hypoglossal nerve
in the hypoglossal nucleus which lies between the
dorsal motor nucleus of the vagus and the midline of the MEDULLA
how does hypoglossol nerve exit the skull
through the hypoglossal cana
function of hypoglossol nerve
tongue movements in speech, food manipulation and swallowing
how to test hypoglossol nerve
- Ask patient to protrude the tongue
- Atrophy & fibrillations (rapid uncontrolled contraction of muscle) are
the tell-tale signs of LOWER MOTOR LESION - which results in the
tongue deviation TOWARDS the lesion
what does damage to hypoglossol nerve cause
paralysis of the IPSILATERAL half of the tongue
- licks the lesion (tongue movement towards lesion)
what is the motor supply to the posterior 1/3 of tongue
hypoglossol, except palatoglossus
pharyngeal branch of vagus
what supplies sensory and taste. to posterior 1/3 of tongue
glossopharyngeal
what is sensory supply to anterior 2/3 of tongue
lingual branch of V3 from trigeminal
what supplies taste to anterior 2/3 of tongue
chorda tympani branch of facial nerve
carried by lingual branch
