Cranial nerves Flashcards
what does it mean to be a branchiomeric
it comes from branchial arches nd innervates corresponding muscles of branchial arches, they are V VII, IX, X XI
what cn’s are Branchiomeric
V VII, IX, X XI
describe Goldberg image of CN locations
I and II are above midbrain
III and IV in midbrain
V, VI, VII, VIII level of pons with some spread
IX, X, XI, XII medulla
what are the two sensory cn’s?
I and II
CN III controls what
medial rectus for adduction of the eye
primary function of Iv
intorsion/rotation around the visual axis, not changing the position of the pupil
LR ___ SO ___ all the rest are ____
6, 4, 3
how many branches does cn V have
3 (ophthalmic, maxillary, mandibular)
what does tensor tympani do
attached to the malleus near the tympanic membrane
Contraction stiffens the ossicluar chain to reduce transmission of sounds mainly in the low frequencies
abducts the eye
lateral rectus muscle (cn 6)
motor cn’s
III, IV, VI, XI, XII
mixed cn’s
V, VII, VIII due to efferent and afferent components, IX, X
cn 1
olfactory - smell
CN 2
optic - Vision
CN 3
Occulomotor - m: pupillary constrictor muscle
Innervates: superior rectus, inferior oblique, inferior rectus, medial rectus
controls medial rectus for adduction of the eye
CN III
CN IV
Trochlear - superior oblique muscle causes intorsion (also downward and out
cn v
trigeminal - Motor (muscles of mastication, tensor tympani)
Sensory (touch, pressure, pain, and temperature from facial dermatomes)
CN VI
Abducens - lateral rectus muscle which abducts the eye
CN VII
Facial - M: facial expression, stapedius muscle)
S: taste anterior 2/3 of tongue and touch, pressure pain temp sensations soft palate and tonsils
Axons of CN VII exit where
pontomedullary junction just medial to CN VIII
Travels in the internal auditory canal
3 branches: chorda tympani (is in middle ear), greater petrosal nerve, facial nerve
what can be altered during middle ear surgery and what happens?
taste changes, chorda tympani
when does stapedius muscle pull
reduces transmission below 1-2 kHz)
What One branch of the facial nerve travels to back of head.
PAM - Post Auricular Muscle
what is bell’s palsy
facial nerve paralysis (CN VII
What symptoms show in bell’s palsy? can they recover?
Loss of blink, eyelid does not close, corneal drying, asymmetric smile
Approx 80% recovery w/in 3 months
does the stapedius muscle work in bell’s pasly?
no, they have a low tolerance of loud sounds
what is the House-Brackmann Facial Paralysis Scale grading?
gets mildly worse as the numbers go up from 1
why do we use nonacoustic middle ear reflex?
By using non-acoustic middle ear reflex we can determine if afferent or efferent is at fault.
if we have present nonacoustic MEMR from touch…
CN VII & Stapedius is working
afferent CN VIII is the issue
if we have absent non acoustic MEMR from touch
CN VII & Stapedius is not working
if absent non acoustic MEMR with touch but is present from air puff…
CN VII/Stapedius is not working
CN V and tensor are working
do we have a distribution of taste budes?
yes, it is mapped some
CN VIII
vestibulocochlear
special sensory
CN IX
Glossopharyngeal - M: (pharyngeal and palatine muscles) and parasympathetic (innervates parotid gland) functions
S: touch, pain and gag reflex from palate, tonsillar and pharyngeal regions; taste from posterior 1/3 of tongue; and chemoreception of arterial blood
CN X
Vagus
branchiomeric
Innervates heart, bronchial smooth muscle, intestinal smooth muscle, larynx and pharynx and aids in digestive secretions
Sensory info gathered from larynx, trachea, lungs, heart and blood vessels
cn xi
accessory
branchiomeric
Accessory nucleus is in the dorsolateral portion of the spinal cord
Separates from vagus nerve and innervates ipsilateral sternocleidomastoid and trapezius muscles (neck and shoulders)
Cranial root also innervates vocal cords
how do we test for damage to CN XI
ask them to shrug their shoulders, one will only go up show
turn their head against resistance
once nerve exits the skull it won’t cross over again, the r nerve goes to right muscles etc.
if nucleus is damaged in the bs it will be opposite the nucleus and not on the same side because it hasn’t crossed over yet.
cn xii
hypoglossal
tongue
what happens to damage of CN XII
if tongue is stuck out they both need to be used equally
if told to stick it straight out and if one side goes out and deviates toward the other the lesion is on that side of the deviation
if damage is coming from cortex before crossing over, this is where we would see the tongue deviation on the opposite side of the lesion
