cranial nerve details Flashcards
where does CN I terminate?
it is a CNS tract that terminates in the olfactory bulb
what are true olfactory nerves?
2nd order ganglion nerve cells which pierce the cribiform plate
what is a perversion of smell?
parosmia
what is an abnormally disagreeable smell?
cacosmia
describe the pathway of the neurons of CN I
primary- unmyelinated; through cribiform plate to olfactory bulb
secondary- myelinated bipolar cells; form olfactory tract and terminate in primary olfactory cortex
tertiary- from primary olfactory cortex to entorhinal cortex (area 28), lateral preoptic, amygdaloid body, medial forebrain
what are the peripheral connections of CN II?
1st order- rods and cones of retina- connect with bipolar cells
2nd order- retinal bipolar cells synapse with ganglion cells near retina surface
3rd order- ganglion cells; myelinated and form optic nerve fibers
4th order- geniculocalcarine tract from lateral geniculate bodies; pass to occipital cortex
what part of the optic radiation curves around the inferior horn of the lateral ventricle?
Meyer’s loop
where does the optic tract pass to?
lateral geniculate bodies
superior colliculi
pretectal region
how does the optic nerve connect to the Edinger-Westphal nucleus?
posterior commissure
how does the optic nerve connect to the other cranial and spinal nuclei?
from superior colliculi via tectobulbar and tectospinal tracts
how does the optic nerve connect to other cortical and subcortical areas?
from the occipital cortex
which fibers are responsible for simple and consensual light reflexes?
fibers from pretectal region
which tract is responsible for visual perception?
geniculocalcarine tract
what area is concerned with light reflex?
pretectal area
what area is responsible for reflex movements of the eye?
superior colliculus
the tectobulbar and tectospinal tracts carry information to?
- cranial and spinal nuclei for involuntary reflexes (accommodation)
- pontine nuclei via corticopontine tract for postural reflexes
what is the retinal area for central vision?
macula
where is vision sharpest and color discrimination best?
fovea centralis
what are the cones responsible for?
sharp vision and color discrimination
what involves the optic nerve or tract, MC cause is MS?
retrobulbar neuritis
what includes various forms of retinitis?
optic or bulbar neuritis
simple, proteinuric, syphilitc, diabetic, hemorrhagic, hereditary
what is associated with decreased visual acuity and change in color of optic disc?
optic atrophy
what involves the optic nerve but doesn’t produce papilledema?
primary optic atrophy- may be d/t tabes dorsalis, MS, or hereditary
what is the sequel to papilledema?
secondary optic atrophy- may be d/t neuritis, glaucoma or increased intracranial pressure
what are the syndromes that involve the optic apparatus?
foster kennedy
amaurotic familial idiocy (tay- sachs)
argyll robertson pupil
holmes-adie
what may be caused by tumors at the base of the frontal lobe and what are its characteristic symptoms?
Foster-Kennedy
ipsilateral blindness and anosmia (atrophy of CN I and II)
contralateral papilledema
what syndrome is cerebromacular degeneration with severe mental deficiency and what is it associated with?
amaurotic familial idiocy (tay-sachs)
blindness, optic atrophy, dark cherry red macula
what reacts only to accommodation is pathologic in tabes dorsalis and also a diabetic complication?
argyll robertson pupil
what is characterized by tonic pupil reaction (myotonic pupil) and absence of one or more tendon reflexes?
Holmes-adie syndrome
what is an inward sinking of the eyeball d/t sympathetic paralysis of small muscle of muller?
enopthalmos
ptosis associated with Horner’s syndrome is due to paralysis of what muscle?
superior tarsal
what are the 3 components of accommodation and what nerve is being tested?
convergence
pupilloconstriction
lens thickening
CN III or higher
what is the Marcus Gunn phenomenon?
pupillodilation with light introduction
what does the swinging light test tell you if the test is positive?
retinal or CN II lesion with the sensory arc decreasing the amount of pupillary motor response
red reflex that is partially or completely blocked indicates
disease of translucent structures of eyes: cornea lens vitreous retinal pigment
what are the findings typically seen with papilledema?
blurred nerve fibers and cup
tortuous, engorged veins and loss of venous pulsations at disc margin
obliteration of cup
disc elevation and edema
what is seen in 5% of population, usually blond caucasians that is hereditary and benign?
pseudopapilledema
inflammation of the optic nerve
optic neuritis
inflammation of the optic disc
papillitis
if inflammation is behind the optic disc and the fundus looks normal but the patient reports vision loss we would assume?
acute retrobulbar neuritis
what are 2 eye signs of arteriosclerosis?
venous engorgement distal to arterial crossing
light reflection off the artery- silver wiring
what are a collection of degenerative deposits that often appear in the fundus of elderly but don’t have clinical significance
drusen bodies
where do the 3 peripheral sensory divisions of trigeminal have their nuclei?
gasserian (semilunar) ganglion
what is the cutaneous area over the angle of the jaw supplied by?
great auricular nerve of cervicoplexus (C2,C3)
the mandibular branch of trigeminal has a recurrent or meningeal branch that innervates what? this explains its association with head pain
dura of middle and anterior cranial fossa
what do the lateral pterygoids do?
right- move jaw tip to left
left- move jaw tip to right
when the ophthalmic division trigeminal is involved in a lesion what happens?
neuroparalytic keratitis- corneal inflammation and ulceration
what disorder is idiopathic, with sharp painful sensation in the 3 branches of trigeminal and what are the AKAs?
trigeminal neuralgia
tic douloureux, fothergill’s neuralgia
what lesion results in paralysis and denervation atrophy of mastication muscles?
LMN lesion of CN V anywhere from pontine nucleus to peripheral cranial nerve
what is a line of communication with the opposite cerebellum to allow for the coordination of planned motor functions
corticopontine fibers
what carries the sensory arc of the corneal reflex and where does it synapse?
CN V carries and synapses of CN VII motor nuclei causing eye to blink
the corneal blink reflex may be absent in the early stages of?
MS
what are the divisions of CN VII in the parotid gland?
temporal
zygomatic
upper buccal
what are the cervicofacial divisions of CN VII?
lower buccal
mandibular
cervical branches
what CN innervates the stapedius muscle?
CN VII
what supplies parasympathetic secretory and vasodilator impulses to the submaxillary, sublingual salivary and lacrimal glands as well as mucus membranes of mouth and tongue?
chorda tympani- branch of facial nerve
what is prosopoplegia?
peripheral facial paralysis
where is the lesion located in Bell’s palsy?
lateral to geniculate ganglion
what are the common factors of peripheral CN VII paralysis?
flaccid paralysis (LMN) ipsilateral facial muscles distal to lesion site
what differentiates stroke from Bell’s palsy?
stroke is central type paralysis- forehead is spared, eyes partially involved, neck and mouth fully involved
peripheral lesions in CN VII must be where to affect taste?
proximal to stylomastoid foramen
complete hemifacial paralysis without loss of taste on ipsilateral 2/3 tongue indicates what?
Bell’s palsy
the vestibular division of CN VIII is connected to what other nerves for coordinating movement of eyes, head and neck in response to stimulation of semicircular canals?
CN III, IV, VI
a “short circuit” or abnormal impulse from what areas can result in nystagmus?
CN III, CN IV, VI and vestibular division of CN VIII
what can be the cause of hyperacusis?
CN VII- stapedius muscle or
centrally located problem
what is the term for visual perception of to and fro movements often accompanying nystagmus?
oscillopia- vestibular disease symptom
a loud noise from out of sight should cause patient to blink. what is the test and reflex?
malingering test
auditopalpebral reflex
CN IX motor fibers innervate what?
stylopharyngeus muscle- elevate larynx, pharynx soft palate
what area controls reflex of pupil and lens?
pretectum
what area controls head and eye movements?
superior colliculus
