Exam 1: Cranial Nerves Flashcards
Which cranial nerves have fibers mediating volitional movement of cranial nerve innervated musculature that arise from the per central gyrus of the cerebral cortex and descend along the corticobulbar tract of the brain?
All but #7
Why is Cranial nerve 7 different from the rest?
It has contralateral innervation in the lower part of the nuclei
Cortico means?
Bulbar means?
cortex
Brain stem
What is another name for the corticobulbar tract?
Upper motor or supra nuclear neruons
Explain the corticobulbar tract
Entire nerve cell resides in CNS and terminate in different cranial nerve motor nuclei in the brain stem. They synapse with LMN forming peripheral CN, which innervate specific muscles
What may be the greatest cause of headaches?
cervicogenic pain
What may be the greatest cause of vertigo?
Cervicogenic dizziness
What is important to keep in mind about the bilateral innervations of Cranial nerves when performing exams?
Equal distribution of right and left brain hemisphere innervation govern the function of a specific body part, which is why lesions of only one cerebral hemisphere will not usually permanently paralyze bilateral symmetrical movements
Which cranial nerves are not true nerves, but fiber tracts?
CN I and II
Cranial nerves that have motor function take their origin from where?
Collection of cells deep within the brain stem (motor nuclei) which are analogous to the anterior horn cells of the spinal cord
Where do sensory cranial nerves originate from?
collection of cells outside of the brainstem, usually in ganglia that may be considered analogous to the dorsal root ganglia of spinal nerves
Cerebellopontine angle lesion can be a problem with…?
Unilateral CN V, VII, VII
Cavernous sinus lesion can be a problem with…?
Unilateral CN III, V, VI
Jugular foramen syndrome can be a problem with…?
Combined unilateral CN IX, X, XI
Combined bilateral CN X, XI, XII problems can be associated with…?
LMN: bulbar palsy
UMN: psuedobulbar palsy
Myasthenic syndrome: involvement of eye muscle, facial weakness
Most common cause of intrinsic brain stem lesion in a younger patient? Older patient?
Younger: MS
Older: vascular disease
The nuclei of the cranial nerves lie chiefly where?
brain stem
The sensory nuclei develop where?
The dorsal or alar plate of the euro tube
The motor nuclei develop where?
Within the basal plate
The alar plate lies where?
In the hindbrain, lateral to the basal in the floor of the 4th ventricle
Explain the dinger-westphal nucleus
Motor nucleus of Oculomotor N (III) and is at the level of superior colliculus
Explain the Nucleus of the Trochelear Nerve
Motor nucleus; CN IV in the mid brain at the level of the inferior colliculus
Explain the Motor nucleus of trigeminal nerve
Motor nuclei of CN V at the level of mid pons
Explain the Nucleus of Abducens nerve
Motor nuclei of CN VI in dorsal pons
Explain the motor nucleus of facial nerve
Motor nuclei of CN VII near caudal border of pons
Explain the Nucleus salivatorius superior and inferior
S: Motor nuclei of CN VII
U: motor nuclei of CN IX
At the border of the pons and medulla
Explain the motor nucleus of vagus nerve
Motor nuclei of CN X in dorsal medulla
Explain the Nucelus ambiguous
Motor Nuclei of CN IX, X, XI in the dorsal medulla
Explain the nucleus of hypoglossal Nerve
Motor nuclei of CN XII in medulla beneath 4th ventricle
Explain the msecencephalic nucleus of trigeminal N
Sensory nuclei of CN V in midbrain
Explain the Main sensory nuclei of trigeminal N
Sensory nuclei of CN Vin pons
Explain the vestibular and cochlear nuclei of acoustic nerve
Sensory nuclei of CN VIII in pons and medulla
Explain the nucleus of tracts solitarius
Sensory nuclei for CN VII and CN IX in dorsal medulla
Explain the Nucelus of spinal tract of the trigeminal N
Sensory nuclei of CN V in dorsal lateral medulla
What are the exams for CN I?
- Observation of external nose
- Observation of internal nasal passage
- Sense of smell
What are the exams for CN II?
- Observation of external eyes
- Visual acuity
- Peripheral vision (confrontation)
- Pupillary light reflex
- Opthalmic exam
What are the exams for CN III?
- Observation of external eyes
- Corneal Light reflex
- Pupillary light reflex
- 6 cardinal fields of gaze
What are the exams for CN IV?
- Observation of external eyes
- Corneal Light reflex
- 6 cardinal fields of gaze
What are the exams for CN IV?
- Observation of external eyes
- Corneal Light reflex
- 6 cardinal fields of gaze
What are the exams for CN V?
- Corneal Blink reflex
- Light touch/ sharp sensation on fact
- Inspect muscle of mastication for tone and strength
- Jaw Jerk reflex
- General sensation of anterior 2/3 of tongue
What are the exams for CN VII?
- Check musculature of face ( smile, look up)
- Taste anterior 2/3 of tongue
What are the exams for CN VIII?
- Observation of external and internal ears
- Rinne Test
- Webber test
- Finger rustle test
- Schwabach test
- Watch tick test
What are the exams for CN IX, X?
- Have patient say “Ahh”
- Gag reflex (posterior 1/3 of tongue)
- Check phonation (Kuh, La, Mi)
What are the exams for CN XI?
- Shoulder elevation
- Muscle strength of SCM and traps
What are the exams for CN XII?
- Stick out tongue
- Tongue in cheek test
What smell can be recognized by nasal epithelium that is not intact?
ammonia
What is anosmia?
Complete loss of smell; does not indicate a cortical lesion normally
What is loss of smell normally associated with?
viral infections, allergic rhinitis, aging, head trauma (skull fracture)
What may a lesion of the uncinate gyrus cause?
It is in the anterior temporal lobe and may cause hallucinations of smell associated with strong smells and deja vu
What is hyperosmia?
increased sense of smell
What is hyposmia?
decreased sense of smell
what is Parosmia?
perversion of smell
What cacosmia?
abnormally disagreeable smell
What are causes of anosmia in both nostrils?
blocked nasal passage
common cold
trauma
aging
What neurons of the olfactory tract are unmyelinated in the upper part of the nasal mucosa and pass through the cribriform plate of the ethmoid bone to the olfactory bulb?
Primary neurons
What neurons of the olfactory tract are myelinated bipolar cells and form the olfactory tract and terminate in the primary olfactory cortex?
Secondary neruons
What are the parts of the primary olfactory cortex?
Periamygdaloid area and perprirform cortex
What neurons of the olfactory tract extend from the olfactory codex or entorhinal croex (28), lateral pre optic area, amygdaloid body, and medical forebrain bundle?
tertiary neurons
Explain the path of CN II
Rods and cones of retina are 1st order and connect with bipolar cells, which connect with ganglion cells near surface of retina.
At optic chiasm, the fibers decussate and these for m the optic tract, which passes to the lateral geniculate bodies, superior colliculi, and pretectal region.
The Geniculocalcarine tract contains 4th order neurons from the lateral geniculate bodies and passes to occipital cortex
what is meyer’s loop?
a fan-like radiating portion that curves around the inferior horn of the lateral ventricle
The central connection of the optic nerve include…?
- Pretectal to edinger westphal via posterior commissure
- Superior colliculi via tectobular/spinal tracts to other cranial/spinal nuceli
- From occipital area to other cortical and subcortical areas
What is the pretectal region concerned with?
- Simple and consensual light reflexes
-
What is the Superior colliculus concerned with?
- involuntary musculoskeletal reflexes
- relfex movements of these and head after optic stimulation
What is the lateral geniculate body concerned with?
- visual perception
- gives rise to geniculocalcarine that
What are cones?
- Located in the small central pit of the retina
- is where vision is sharpest and color discrimination is most acute
- Stimulated by high intensity light
What are rods?
- React to low intensity light
- Fucntion in twilight and night vision
what is Retrobulbar neuritis?
involves optic nerve or tract– MS
What is optic or bulbar neutritis?
includes various form of retinitis (syphilis, diabetic, hemorrhagic)
What is papilledema?
- AKA “Choked disc”
- increased intracranial pressure due to brain tumors, accesses, hemorrhage, hypertension
What is optic atrophy?
decreased visual acuity and a change is the color of the optic disc to light pink, white, or grey
What is primary optic atrophy?
caused by processes that involve the optic nerve and does not produce papilledema
- tabes dorsalis, MS, heredity
What is secondary optic atrophy?
Has papilledema
- neuritis, glaucoma, increased intracranial pressure
What is foster kennedy syndrome?
may be caused by tumors at the base of the frontal lobe and is characterized by ipsilateral blindness and anosmia (with atrophy of the optic and olfactory nerve) and central lateral papilledema
What is amaurotic familial idiocy (Tay-sachs disease)?
cerebromacular degeneration with sever mental deficiency occurring in jewish families and is associated with blindness, optic atrophy
What optic syndrome is associated with a dark cherry red spot in the place of the macula lutea?
amaurotic familial idiocy (Tay-sachs disease)
What is argyll robertson pupil?
reacts only to accommodation and it has neither a direct or indirect reaction to light. Occurs as diabetic complication
What is holmes-adie syndrome?
tonic pupillary reaction and the absence of more than one tendon reflexes.
- Very slow contractions to light and slow dialtion
- Have abnormal sensitivity to methacholine
- MC in females and benign
What is the adler-scheie test?
When a methacholine solution is instilled into the conjunctival sac
-Has a demonstrable effect in affected eyes of holmes-adie syndrome (tonic pupils constrict and pupils of normal eyes remain unaffected)
What is heterotropia?
Deviation of bilateral eye alignment
What is exotropia? Esotropia? Hypertropia? Hypotropia?
EX: outward/lateral movement of eye
ES: inward/medial movement
HYPER: up
HYPO: down
Disease of what cranial nerve are sometimes responsible for deviation of eye alignment?
III, IV, VI
What is the medial longitudinal fasiculus?
- Primary function is to coordinate eye movements by interconnecting the nuclei of CN III, IV, VI
- Ex of lesion is MS
What are the 2 supra nuclear pathways for eye movement?
Frontal lobe: control saccadic (rapid or darting) eye movement
Occipital lobe: controls smooth or following eye movements
What is nystagmus?
- Involuntary eye oscillations
- fast component is frontal lobe and slow movement is occipital lobe
What are the characteristics of a disease of CN III?
More obvious due to the accompanying parasympathetic manifestations (ptosis, corectasia)
What are the characteristics of a disease of CN IV?
Difficulty for the patient when looking down and in
What are the characteristics of a disease of CN VI?
Patient is unable to laterally deviate the eye on the same -side of the lesions
What does pathological involvement of the motor portion of the eye reflex result in?
CNII
-results in decreased ability to carry out the act of pupilloconstriction in the ipsilateral eye
What does loss of diencephalon or midbrain function result in?
unopposed sympathetic dominance, light as a stimulus causes no pupillocontriction and the pupil is fixed and dilated
-Bilateral = brain dead
What are the signs and symptoms of horner’s syndrome?
- lesion of the neck proximal to carotid
- Ptosis
- Pupilloconstriction (cornomiosis)
- Facial anhydorsis (ipsilateral)
- Ipsilateral facial vasodialtion
Lesions along the sympathetic pathway distal to the bifurcation of the common carotid arteries will cause what?
- only pupilloconstriction and ptosis
- Vasodilation and anhydrosis if along external carotid
- Enopthalmos
What lesions would eyelids ptosis indicate?
- hypothalamus
- brain stem or spinal cord
- Peripheral CN III
- Peripheral sympathetic nerves
- Myonerual pathways
- possible muscular and local causes
What is the limbus to lid distance?
The lower eyelids should form a tangent from the limbus
What is the ciliospinal reflex?
pinching the skin on patient’s neck and observing for a brisk bilateral puillodilation
-used to assess sympathetic function in head and face
What is the difference between legal blindness and medical blindness?
Legal blinds is a legal issue and medical blindness is a failure to perceive a light stimulus
What are the 3 components of accommodation?
- Convergence (CN III)
- Pupilloconstriction (PS fibers in CN III)
- Lens thickening (ciliary muscles, CN III)
What is concomitant eye movement?
disturbance of image formation due to a cloudy cornea, cataract or macular lesions
What is a non-concomitant eye movement?
results in diplopia due to the brains inability to resole the images
Nystagmus is thought to be caused by conflicting proprioceptive inputs from what sources?
CN VII, cervical and cerebellar sources
End point nystagmus is common. T/F
True.
Pathological nystagmus usually begins well before endpoint
What is a simple and sensitive method to test equal pupilloconstriction?
Swinging flashlight test
What is the marcus-gunn phenomenon?
Apparent pupillodilation with light introduction
-CN III lesion
What 4 areas of the fundus should be examined?
- Optic disc
- vessels
- macula
- general background
Increased cup to disc ratio could indicate what disease?
glaucoma
What are some findings often seen with papilledema on the fundoscopic exam?
- Blurred nerve fibers and cup
- engorged veins and pulsations
- Obliteration of physiological cup
- Disc elevation and edema
A pseudopapilledema has be seen in up to what percentage of the population?
5%– hereditary and benign
What aspect of optic neuritis separated / papilitis differentiates it between papilledema?
There is visual complaint and pain
What are collections of degenerative deposits that often appear in the funds of elderly people?
Drusen bodies
What are the 3 divisions of the trigeminal nerve?
V1: opthalmic
V2: maxillary
V3: mandibular
What area does CN V spare?
The angle of the jaw
The mandibular branch of CN V has a recurrent or meningeal branch that innervates what area?
The dura of the middle and anterior cranial fossa
What are the muscles of mastication?
- Temporalis
- masseter
- medial pterygoid
What does the lateral pterygoid do?
opens the jaw or causes lateral movement of the jaw (in the contralateral way)
What might be responsible for bilateral jaw paralyzing issues?
Bilateral corticobulbar lesions and sometimes an acute unilateral corticobulbar lesion along with a CN V LMN lesion
What is a condition of the ophthalmic division of CN V where there may be corneal inflammation and ulceration?
Neuroparalytic keratitis
-trouble losing eyelids
What is an idiopathic syndrome or sharp, painful facial sensation in the clear distribution of the ophthalmic, maxillary, or mandibular division of CN V?
Trigeminal neuralgia (Tic Douloureux or Fothergill’s neuralgia)
Cranial nerve V carries the sensory arc of the corneal reflex and synapses on what nerve, causing the eye to blink?
CN VII
The corneal blink reflex may be absent in early cases of what disease?
MS
Where does CN VII divide into the temporofacial and cervicofacial divisions?
within the substance of the parotid gland
What nerve innervates the stapedius muscle?
CN VII
parasympathetic stimulation of CN VII causes what? Sympathetic?
PS: increase secretion of thin and water saliva
S: scan supply of thick and turbid saliva
What is peripheral facial paralysis called?
prosopopledia
How can bells palsy be differentiated from a stroke?
In a stroke, the forehead is spared
What is the complete loss of taste?
ageusia
Peripheral lesions in CN VII must be proximal to what area to affect taste?
Stylomastoid foramen
What test confirms bells palsy?
Complete hemifacial paralysis without loss of taste on the ipsilateral anterior 2/3 of the tongue
Where are the receptors for the vestibular division of CN VIII?
semicircular canals, utricle ,saccule
What is the pathways for the vestibular division of CN VIII?
From semicircular canals, utricle, and saccule to the vestibular ganglion to vestibular nerve which travels through the IAM to brain stem.
-The fibers terminate on vestibular nuclei or pass through inferior cerebellar peduncle as part of vestibulocerebellum
What pathways is the vestibular division of CN VIII connected to?
CN III, IV, VI
Where are the receptors for the cochlear division of CN VIII?
within the organ of corti inside the cochlea
What is the pathway for the cochlear division of CN VIII?
Impulses travel to bipolar cells of cochlear ganglion, and energy as cochlear nerve, through the IAM to cochlear nuclei to the ipsilateral lateral lemniscus, and then ascend to inferior colliculus and medial geniculate body
-Terminate as auditory radiations on cortex of transverse temporal convolution (hesuchl’s gyrus)
Which part of CN VIII has the sole function to provide hearing?
Cochlear division
What is hypoascusis? Hyper?
Hypo: decrease or loss of hearing; conduction loss
Hyper: increasing in intensity of hearing due to CN VII disorder or central located
Why type of lesions are not often associated with hearing loss but more commonly with hallucinations of hearing?
Central lesions
What are some common etiologies for conductive hearing loss?
Auditory canal obstruction
Trauma of tympanic membrane
Trauma/aging of oscicles
Accumulation of fluid in middle ear
What are some common causes of sensorineural hearing loss?
attributed to diseases of end organ (organ of corti) or the auditory nerve
What are symptoms of vestibular diseases?
ALWAYS vertigo Nausea, anxiety, oscillopsia Unsteadiness with or without falling nystagmus Pallor, sweating, vomiting, hypotension
What is oscillopsia?
visual perception of rapid to and fro movements often accompanying nystagmus
If there is no fast component to nystagmus, what is it termed?
pendular
If the cervicospinal proprioceptive disease test comes back positive, what is the mechanism of disease?
cervical mechanoreceptors are over stimulated
What exam tests for the auditopalpebral reflex (a loud noice from out of sight causing the patient to blink)?
Malingering test
Which CN has innervation to the stylopharyngeus?
CN IX
Disorders of CN IX are common and always include disturbance of speech. T/F
False
Never any speech issues, and disturbances in swallowing are never that bad unless bilateral
What is unilateral paralysis of CN X follow by?
transient paresis of the soft palate, pharynx, and larynx on affect side along with absent gag reflexes and oculocardiac reflexes
Complete bilateral CN X paralysis is compatible with life. T/F
FALSE
What is the loss of voice called?
aphonia
What is faulty articulation called?
dysarthria
What is no articulation called?
anarthria
What is faulty swallowing called?
Dysphagia
What is no swallowing called?
aphagia
What is hyper/hyponasal?
Hyper: increase air in nasal cavity
Hypo: decreased air in nasal cavity
Which side does the usual deviate to in CN X lesion?
affected side
What are the 2 parts of CN XI?
- cranial or accessory potion to the vagus
2. spinal portion (larger)
What is the path of the nerve for CN XI?
Spinal portion: arise from ventral horn, ascend through foramen magnum and exit through jugular foramen and supply traps and SCM
CN X supplies the upper portion of the traps, what innvervates the lower portion?
3rd and 4th cervical nerves
Paralysis of the tongue is the cardinal finding in what CN disease?
CN XII
