Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neurology > Lecture: Vestibulocochlear function and dz > Flashcards

Lecture: Vestibulocochlear function and dz Flashcards

1
Q

Vestibular function

A
  • Maintenance of posture and balance
  • Function intimately with the cerebellum
  • Peripheral or Central
  • Critical neuroanatomic localization
    • huge impact on DDX and prognosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

CN VIII

A
  • Only CN not to exit skull
  • purely sensory
  • two portions
    • vestibular
    • auditory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Conductive Deafness

A
  • Occlusion
    • congenital or acquired
    • rupture of tympanic membrane
    • fluid, exudate, foreign body, mass
    • age (ossicles)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sensorineural Deafness

A
  • Alterations of neural structures of auditory pathway
    • Congenital
      • hair cells of the OoC
    • Acquired
      • infection
      • intracranial disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Congenital sensorineural deafness

A
  • Hair cells of the organ of Corti
  • American Paint horses
    • especially white coat/blue or violet iris
  • Lethal White Foal Syndrome
  • Dalmatians
  • White dogs & cats with blue eyes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Vestibular Labyrinth

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Vestibular labyrinth

A
  • Utricle and saccule
  • Located in the large vestibule
  • Detect static or kinetic position
    • gravity & linear acceleration
  • Receptor: macula
    • covered by hair cells projecting into gelatinous otolithic membrane
    • otolitic membrane contains otoliths (statoconia)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Semicircular Ducts

A
  • 3 in the semicircular canal
  • at right angles to each other
  • detect angular movements of the head
  • Receptor: crista ampullaris
    • covered by hair cells projecting cilia into gelatinous cupula
      • no otoliths
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Entry into skull

A
  • Axons from bipolar neurons in petrous temporal bone enter cranial vault through internal acoustic meatus at cerebellomedullary angle
    • rostral medulla oblongata
    • This is CN VIII
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Entry into the brain

A
  • At level of trapezoid body and caudal cerebellar peduncle
  • Most axons synapse on CN VIII nuclei
  • Few axons bypass CN VIII nuclei to enter cerebellum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Vestibular Nuclei

A
  • Four on each side of brainstem
    • ventrolateral wall of 4th ventricle
    • Huge
  • Axonal projections
    • spinal cord: vestibulospinal tracts
      • limb extensor tone (anti-gravity muscles)
    • Rostrally: Medial longitudinal fasciculus (MLF)
      • Ocular and head movements
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Vestibulospinal tracts

A
  • Lateral vestibulospinal tract (mainly)
    • nucleus projects in ipsilateral ventral funiculus
    • synapse on interneurons in spinal cord ventral gray
    • mediate facilitation of extensor muscles and inhibition of flexor muscles
    • ipsilateral side
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

MLF

A
  • Medial longitudinal fasciculus
  • Rostral projections
    • to nuclei of CN III, IV & VI
    • responsible for oculocephalic reflex
  • Caudal projections
    • medial vestibulospinal tract
    • maintain body and limb position relative to head
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Extraocular muscles

Innervation

A
  • CN III: Oculomotor n.
    • Dorsal, medial and ventral recti mm
  • CN IV: Trochlear n
    • Dorsal oblique m.
    • on opposite side
  • CN VI: Abducent n.
    • Lateral rectus & retractor bulbi mm.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Physiologic Nystagmus

A
  • Moves eyes to hold images during head rotation or target motion
  • Receptor: ear and CN VIII
  • MLF connects VIII to III/IV/VI
  • Bilateral, opposite effects on CN II, IV, VI
17
Q

Vomiting Center

A
  • In the reticular formation of the medulla
  • Receives afferent input from the vestibular portion of the vestibulocochlear nerve
    • motion sickness
18
Q

Cerebral Projections

A
  • Synapses in thalamus
  • provides conscious awareness of the body’s position in space
19
Q

Clinical evaluation

A
  • Think about abnormalities in maintenance
  • vestibular inputs are bilateral and tonic
  • if you excite one side, you get ipsilateral facilitation of extensors and contralateral facilitation of flexors
20
Q

If a lesion prevents activation of one side…

A
  • The ipsilateral nuclei won’t be as excited as other side
    • facilitation of extensors on normal side
    • lack of facilitation on affected side
  • body is ‘pushed’ towards abnormal side
21
Q

Clinical Signs

A
  • Head tilt
  • Circling, leaning, falling towards lesion
  • Unilateral or asymmetric ataxia toward lesion
  • Abnormal eye position or movements
  • Nausea
  • +/- postural reaction deficits
22
Q

Nystagmus

A
  • Involuntary movements of the eyes
    • Jerk: fast and slow phases of eye movements
    • Defined by direction of fast phase
23
Q

Physiologic nystagmus

A
  • vestibulo-ocular, Doll’s eye, oculocephalic reflex
24
Q

Pathologic nystagmus

A
  • Horizontal, rotary, vertical
25
Q

Disconjugate nystagmus

A
  • one eye goes one way, and one goes the other way
    • this is bad
26
Q

Pendular Nystagmus

A
  • Siamese and Himalayan cat things
  • not nystagmus
27
Q

Vestibular Localization

A
  • Peripheral
    • ear: canal, bulla, CN VIII
  • Central
    • brainstem or cerebellum
  • Isolate the clinical signs that involve only one!
28
Q

Vestibular Lesion

Peripheral

A
  • NO proprioceptive deficits
  • Normal mentation
  • Head tilt towards lesion
  • Only deficits in CN VII or VIII
  • Strabismus
  • Nystagmus
    • any direction
29
Q

Vestibular Lesion

Central

(Brainstem, cerebellum)

A
  • Proprioceptive deficits
  • Dullness, stupor
  • Head tilt
  • Other CN deficits possible
  • Strabismus
  • Nystagmus
    • any direction
    • positional, vertical, dysconjugate MUCH more suggestive
30
Q

Peripheral Vestibular

A
  • Head tilt, ataxia, nystagmus
  • CN VII: Facial n.
    • Exits the skull right above the tympanic bulla
    • Innocent bystander
  • Temporohyoid osteoarthropathy in the horse
  • CN VII
  • CN VIII
  • Unilateral
  • Bilateral
  • Head tilt & CN VII
  • Horner’s syndrom
31
Q

Horner’s syndrome

A
  • Sympathetic dysfunction
  • Ptosis (droopy eyelid), miosis, enophthalmos, protruding nictitans
  • Sympathetics to eye, course near/in the middle/inner ear
  • Innocent bystander
32
Q

Central Vestibular

A
  • CN deficits other than CN VII & VIII
  • Mentation changes
    • Ascending reticular activating system
  • Proprioceptive deficits
    • these pathways don’t go through peripheral system
  • cerebellar and forebrain signs
33
Q

Cerebellar Syndrome

A
  • Cerebellum is inhibitory, modulatory
  • If disinhibited => spastic
    • hypermetria, ataxia, intention tremors
  • Ipsilateral signs
34
Q

Paradoxical Vestibular Syndrome

A

Always central: cerebellum/brainstem

  • Head tild away from lesion
    • fast phase nystagmus may be towards
  • Always central
    • Flocculonodular lobe, CCP, rostral & middle vestibular nuclei and dorsal roots of C1-C3
  • lesion on same side as proprioceptive deicits

Neurology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions