Ch 6 Neurologic Exam Cranial Nerves Flashcards
How many cranial nerves are there?
12
Cranial nerves originate from where?
brain stem (mid brain, pons, medulla)
Cranial nerves are grouped based on which 3 functions
sensory (I, II VIII)
motor (III, IV, VI, XI, XII)
mixed (V, VII, IX, X)
CN I is called
Olfactory Nerve
Where does olfactory nerve project from and to
from olfactory regions to midbrain
Function of CN I?
smell
Olfactory loss is also known as
anosmia
Anosmia can occur with what condition
subfrontal masses (e.g. tumor, abscess)
trauma to orbitofrontal region
viral infections due to damage to olfactory neuroepithelium
CN II is called
Optic Nerve
Optic Nerve projects from where to where
retina to the midbrain
Function of CN II?
Vision
Abnormality in optic chiasm causes
loss of visual temporal fields (bitemporal hemiapnosia)
Postchiasmic lesions can result in
loss of half of a contralateral visual hemifield on the same side of both eyes (homonymous hemiapnosia)
Prechiasmic lesions can result in
monocular blindness
Involvement of optic radiation tract (tract that connects LGN to primary visual cortex) in posterior temporal lobe results in
loss of superior quadrant visual field on contralateral side (homonymous superior quadrantanopsia)
Involvement of optic radiation in parietal lobe results in
loss of inferior quadrant visual field on the contralateral side (homonymous inferior quadrantanopsia)
CN III is known as
Occulomotor Nerve
Where does the occulomotor nerve originate and project to
originate from midbrain and projects to extraocular muscles
function of CN III
Eye movements Medially (adduction), superiorly, inferiorly
pupil constriction
CN IV is known as
Trochlear Nerve
CN VI is known as
Abducens Nerve
Where does the trochlear nerve originate and project to
originate from midbrain and project to superior oblique muscle
Where does the abducens nerve originate and project to
originate from pons
projects to lateral rectus muscle
How does one evaluate CN IV and VI?
observing vertical and lateral eye movements
Compression of CN IV can be caused by what?
cerebellar tumors
damage to shear injury from head trauma and produce vertical diplopia
Compression of CN VI can be caused by
elevated intracranial pressure and produces horizontal diplopia (failure to adduct)
CN V is known as
Trigeminal Nerve
Where does the trigeminal nerve originate and project to
originate from pons and innervates t he upper, middle, lower portions of the face via ophthalmic, maxillary and mandibular divisions
Function of CN V?
sending pain, touch and temperature sensations from your face to your brain.
How is function of CN V assessed?
assessing facial sensation, corneal reflex, jaw jerk reflex
CN VII is known as
facial nerve
Where does the facial nerve originate and project to
originate from lower pons and upper medulla
Function of CN VII
control muscles of facial expression
parasympathetic (tears and salivation)
visceral sensory (taste)
general somatosensory functions
How to assess function of CN VII?
looking for asymmetry in spontaneous facial expression
CN VIII is known as
vestibulocochlear nerve
Where does the vestibulocochlear nerve originate and project to
projects from auditory canal to pontomedullary junction
CN VIII function
auditory and vestibular functions
Assessment of CN VIII functions
Rinne test (vibrating tuning fork placed outside each ear to assess air conduction and on forehead or mastoid to assess bone conduction)
Dix Hallpike maneuver
tests vestibular function - differentiate peripheral from central causes of vertigo
Vertigo with nystagmus suggests dysfunction in which CN?
CN VIII (vestobulocochlear nerve)
CN IX is known as
Glossopharyngeal nerve
Where does the glossopharyngeal nerve originate and project to
stems from medulla and projects to pharynx, middle ear, posterior tongue
function of CN IX
sensory info to mouth and throat
swallowing, taste
assessment of CN IX?
inducing a gag reflex, touching the uvula
CN X is known as
vagus nerve
where does vagus nerve originate from and project to?
originates in medulla, innervates to heart, lungs, digestive tract
function of CN X
regulation of internal organ functions, such as digestion, heart rate, and respiratory rate
CN XI known as
Spinal accessory nerve
where does spinal accessory nerve originate from and project to?
stems from spinal cord and projects to sternocleidomastoid muscle and trapezius
How to assess CN XI?
shrug shoulders
CN XII known as
hypoglossal nerve
where does hypoglossal nerve originate from and project to?
originate in medulla and projects to tongue muscles
How to assess hypoglossal nerve?
examining tongue protruded
tongue will deviate toward side of lesion
Mnemonic of 12 cranial nerves
Oh Oh Oh They Traveled And Found Voldemort Guarding Very Ancient Houses
Name the Sensory Motor Both Functions of the cranial nerves
Some Say Money Matters
But My Boyfriend Says
Big Boobs
Matter Most
Hemianopia
when you lose sight in half of your visual field
