Lab Manual 5 Flashcards
CN1
olfactory nerve
CN2
optic nerve
CN3
oculomotor nerve
CN4
trochlear nerve
CN5
trigeminal
CN6
abducens
CN7
facial
CN8
vestibulocochlear
CN9
glossopharyngeal
CN10
vagus
CN11
accessory
CN12
hypoglossal
olfactory nerve function
sensory impulses from nose for sense of smell
optic nerve function
sensory impulses from eye for vision
oculomotor nerve function
motor impulses to eye muscles for movements of the eyes
trochlear nerve function
motor impulses to eye muscles for movements of the eyes
trigeminal nerve function
sensory impulses info from face, scalp, and teeth
- motor impulses to temporal and masseter muscles for chewing
abducens nerve function
motor impulses to eye muscles for abduction of the eyes
facial nerve function
sensory impulses from some taste buds of tongue
- motor impulses to muscles controlling facial expressions like frowning, smiling, etc
vestibulocochlear nerve function
sensory impulses from ear for senses of both sound and balance
glossopharyngeal nerve function
- sensory impulses from throat and some taste buds at the back of the tongue
- motor impulses to muscles of throat for swallowing and to salivary glands
vagus nerve function
- sensory impulses from throat, larynx, thoracic and abdominal organs
- motor impulses to stimulate digestive organs, to slow heart rate, to cough, and to swallow
accessory nerve function
motor impulses to trapezius and sternocleidomastoid muscles of the neck and upper shoulder for shoulder movements and movements of the head
hypoglossal nerve function
motor impulses to muscles of the tongue for most tongue movements
where are the nerve fibers of the afferent sensory part of the pupillary light reflex within
optic nerve (CN2)
where are the nerve fibers of the efferent motor control part of the pupillary light reflex neural pathway within
the oculomotor nerve (CN3)
what is the function of the swinging flashlight test
indicating potential problems with either cranial nerve by comparing the direct and consensual light reactions of the pupils in both eyes
what cranial nerves does the pupillary light reflex require
CN2, CN3, and central brain stem connections
what does light shined in an eye usually result in
constriction of that pupil (direct response), and simultaneous constriction of contralateral pupils (consensual response)
why does the consensual response occur in the pupillary light reflex
the light sensory info entering the brain from one eye causes the same reflex response in the non-stimulated eye
symptom of CN2 lesion
unresponsive pupillary light reflex on both sides
why do the symptoms of a CN2 lesion occur
the CN2 lesion creates an issue with the afferent sensory info from the eye getting to the brain; the problem is not with the motor function responsible for the constriction of the pupil
symptoms of CN3 lesion
unresponsive ipsilateral pupillary constriction on the affected side (the pupil is “fixed and dilated”) when light is shined in either eye
- no direct response in the affected eye
- no consensual response in the affected eye when light is shined on the unaffected eye
why do the symptoms of the CN3 lesion occur
the motor function controlling the constriction of the pupil is affected and despite the sensory info getting to the brain the pupil can’t respond
- there is not a problem with the sensory info entering the brain to affect the contralateral eye
what would happen if a light is shined in the right eye of an individual with normal sight
direct response in right eye, consensual response in left eye
what would happen if a light was shined in the left eye of an individual with normal sight
direct response in left eye, consensual response in right eye
what would happen if a light was shined in the right eye of an individual with left CN2 damage
direct response in right eye, consensual response in left eye
what would happen if a light was shined in the left eye of an individual with left CN2 damage
no direct response in left eye or consensual response in right eye because sensory info is not getting to brain from the left CN2
what would happen if a light was shined on the right eye of an individual with left CN3 damage
direct response in right eye, no consensual response in left because the motor control of the left is absent
what would happen if a light was shined on the left eye of an individual with left CN3 damage
no direct response in left eye but consensual response in right eye is intact
- sensory info is getting to brain from left CN2, but the motor control (CN3) of the left affected pupil is absent
symptoms of 3rd nerve palsy
- complete ptosis
- eye down and out
- dilated pupil which is unresponsive to light and accomodation
symptoms of 4th nerve palsy
- double vision going down stairs or reading books
- ask patient to turn the eye in and then to look down; may cause vertical hypertropia (eye moves up and in)
symptoms of 6th nerve palsy
failure of lateral movement Nystagmus
how to test CN5
touch the patient’s face while clenching their jaw to check two point discrimination
how to test CN7 motor component
have the subject smile or frown; lack of symmetry may indicate damage to the nerve
how to test CN7 sensory component
place different flavors on the tongue to check if the subject can tell the difference if they hold their nose
how to test CN8
Weber test hold a tuning fork down in the center of the patient’s forehead and ask if it is louder in each ear - normally it should be heard equally in both ears
Weber test condition A
normal - sound is equally loud in both ears; sound does not lateralize
Weber test condition A DELETE
normal - sound is equally loud in both ears; sound does not lateralize
Weber test condition B
conductive loss - sound lateralizes to “poorer” ear owing to background room noise, which masks hearing in normal ear
- “poorer” ear (the one with conductive loss) is not distracted by background noise, thus has a better chance to hear bone-conducted sound
Weber test condition C
sensorineural loss - sound lateralizes to “better” ear or unaffected ear
- poorer ear (the one with nerve loss) is unable to perceive the sound
how to test CN9
Rinne test
Rinne test
a tuning fork test used to clinically test hearing deficiencies in patients
- place a sounding tuning fork on a patient’s mastoid process and then next to their ear and ask which is louder
- compares air conduction with bone conduction thresholds
what will a normal patient’s result of the Rinne test be
they will find the position by their ear louder
- because air conduction is better than bone conduction under typical conditions
what will a patient with conductive deafness’ results be
they will find the bone conduction position louder
how to test CN8 vestibular function
Romberg test
Romberg test
patient stands heel to toe and closes eyes; positive test = patient starts to sway or fall over
how to test CN9 and CN10
have the subject swallow and cough; can result in a bovine cough with damage to nerves 9 and 10 or delayed swallow
how to test CN12 motor for tongue movement
stick out tongue and move side to side; damage results in deviation of symmetry towards side of lesion
testing CN11
place your hands on the subjects shoulders from the back; as you apply resistance, have them shrug shoulders upward. contraction should be symmetrical
