Vestibular System Flashcards
Which of the following components of the vestibular system found in the inner ear and is responsible for relaying head postion and motion via APs?
A. Vestibulothalamocortical Network
B. Central Cestibular Nuclei
C. Peropheral Receptor Apparatus
D. Vestibulospinal Network
E. Vestibuloocular Network
eropheral Receptor Apparatus
Which of the following components of the vestibular system is found within the brainstem and is responsible for integrating and distributing information needed to control motor activity and have spatial awareness?
A. Vestibulothalamocortical Network
B. Central Cestibular Nuclei
C. Peropheral Receptor Apparatus
D. Vestibulospinal Network
E. Vestibuloocular Network
Central Cestibular Nuclei
Which of the following components of the vestibular system is found within is involved in the control of eye movements while the head moves?
A. Vestibulothalamocortical Network
B. Central Cestibular Nuclei
C. Peropheral Receptor Apparatus
D. Vestibulospinal Network
E. Vestibuloocular Network
Vestibuloocular Network
Which of the following components of the vestibular system coordinates the head movements with the acial and postural muscles?
A. Vestibulothalamocortical Network
B. Central Cestibular Nuclei
C. Peropheral Receptor Apparatus
D. Vestibulospinal Network
E. Vestibuloocular Network
Vestibulospinal Network
Which of the following components of the vestibular system is involved with awarebess of movement and spatial orientation?
A. Vestibulothalamocortical Network
B. Central Cestibular Nuclei
C. Peropheral Receptor Apparatus
D. Vestibulospinal Network
E. Vestibuloocular Network
Vestibulothalamocortical Network
There are two major vestibular receptor organs that include the Semicircular canals and the otolithic organs of the utricle and saccule.
What head movements are detected by the Semicircular canal?
What head movements are detected by the otolithic organs of utrcle and saccule?
Semicircular Canal: Angular acceleration (rotational head movements)
Utricle and Saccule: Linear Acceleration (translational head movements)
Receptor cells that leave the vestibular organs (semicicurclar canals and utricle/saccule) are innervated by primary afferent fibers from what ganglion?
In general, the central processes of these fibers enter the brainstem and terminate on what two structures?
Vestibular Ganglion (Scarpa ganglion)
Ipsilateral vestibular nuclei and cerebellum
In general what leads to vestibular disease?
A. Disturbances in volume of endolymph
B. Disturbances in ion concentration of perilymph
C. Disturbance in volume and ion concentration of endolymph
D. Disturbacnes in volume and ion concentration of perilymph
Disturbance in volume and ion concentration of endolymph
What artery is the primary supply of the vestibular apparatus?
What artery also feeds the semicircular canals, but is not the primary source?
Labyrinthine A. (branch of the AICA that enters through Internal Auditory Meatus)
Stylomastoid A.
Interuption of the Labyrinthine A. will compromise the vestibular organs leading to what types of presentation/symptoms?
Vertigo
Nyastagmus
Unstable Gait
Meniere’s disease presnts with symptoms of fluctuating hearing loss, vertigo, positional nyastagmus, and nausea. What causes this disease to develop?
What are some treatments for this disease?
Disruption in the normal endolymph volume that leads to endolymphatic hydrops, also known as an abnormal distention of the membranous labyrinthe=
Treatment includes a diuretic or salt restricted diet, or possibly adding a shunt to drain the swollen sac
Hair cells determine positional changes as they are moved by endolymph. There are two types of hair cells Type I and Type II, that have no real significant difference except for what?
What nerve innervates these hair cells?
Type 1 has one large nerve terminal connection (nerve calyx)
Type 2 hair cells make several individual connections/synapse
The movement of sterocilia (hair cells) towards or away from the kinocelium is what activates or registers the vestibular system.
What direction does the sterocilia need to move in order to depolarize and activate?
Hyperpolarize and inhibit?
Sterocilia TOWARDS kinocelium results in depolarization and activation
Sterocilia AWAY from jinocilium results in hyperpolarization and inhibition
Correctly describe the detection mechanism that occurs within the semicircular canal. Start by describing the anatomical relationship of the structures involved
The semicircular canal contains the ampulla, where hair cells are located inside and embedded on the cristae along the base of the ampulla. Hair cells extend into the cupula.
Rotational/angular acceleration moves the endolymph causing it to displace the cupula. The movement of the cupula displaces the hair cells, which are then excited or inhibited depending on direction
Correctly describe the detection mechanism that occurs within the utricle and saccule. Start by describing the anatomical relationship of the structures involved
The utricle and Saccule contain the maculae. Inside the maculae are sterocilia that extend into the otolith membrane. The otolithic membrane is covered by otoconia (ear stones).
Gravity/Linear acceleration displaces the otoconia and bends the underlying sterocilia
Nerves leaving the the ampulla and the maculae converge as what primary afferent fiber before entering what junction found within the brainstem?
CN VIII
Pontomedullary Junction
Secondary vestibular afferents leave the pontomedullary junction and project to what nuclei?
What information do these nuclei encode?
Vestibular Nuclei (superior, medial, lateral, inferior)
Direction
Speed of movement
Head position
The secondary neurons that leave the vestibular nuclei target what 3 cranial nerve nuclei?
What other four 4 structures are targets so that we can integrate information?
CN: 3, 4, 6
Vestibulocerebellum
Spinal Cord
Reticular Formation
Thalamus
Vestibulovestibular fibers are secondary fibers that make reciprocal connections with analagous contralaterally located nuclei. Which of the following correctly expresses what these fibers signal when the head turns right?
A. Left afferents are inhibited, right afferents are inhibited
B. Left afferent are inhibited, right afferents are inhibited
C. Left afferents activated, right afferents activated
D. Left afferents are inhibited, right afferents are activated
Left afferents are inhibited, right afferents are activated
Spinovestibular fibers arise from all spinal cord levels to provide what type of input?
A. Nociceptive
B. Proprioceptive
C. Discrimintive touch
D. Pain and temperature
Proprioceptive
Look at it Again
What is the only sensory organ body that sends direct projections to the cerebellum?
Vestibulocerebellar Fibers
There are primary and secondary vestibulocerebellar fibers that course through thejuxtaretiform body found inthe inferior cerebellar peduncle.
What do the primary vestibulocerebellar fibers target?
What do primary vestibulocerebellar fibers terminate as?
What do secondary vestibulocerebellar fibers target?
Primary Vestibulocerebellar Fibers
- Target: Dentate nucleus
- Terminate: Mossy fibers
Seondary Vestibulocerebellar Fibers
- Flocculondular Lobe
- Fastigial Nuclei
- Dentate Nuclei
What is dizziness?
A nonspecific term that general refers to spatial disorientation
Vertigo is an illusion of body motion, that is sub divided into to types: subjective and objective vertigo. Define both subtypes?
Subjective Vertigo: when you feel like you’re spinning
Objective Vertigo: when it feels like the room is spinning
Which of the following correctly describes Benign Paroxysmal Positional Vertigo? What causes this disorder?
A. Triggered by specifc changes in body motion like turning over in bed that causes brief episodes of vertigo
B. Patients present with hearing loss (100% of the time), gait difficulties (70%), and tinnitus
C. Patients present with severe vertigo, nausea, and vomiting, but no accompanying hearing loss or other CNS deficits
D. None of the above
A. Triggered by specifc changes in body motion like turning over in bed that causes brief episodes of vertigo
- Cause:*
- Otoconial crystals from the utricle seperate from the otolithic membrane and become lodged in the cupula of a semicircular canal (cupulolithiasis)*
Which of the following correctly describes VEstibular Neuritis? What causes this disorder?
A. Triggered by specifc changes in body motion like turning over in bed that causes brief episodes of vertigo
B. Patients present with hearing loss (100% of the time), gait difficulties (70%), and tinnitus
C. Patients present with severe vertigo, nausea, and vomiting, but no accompanying hearing loss or other CNS deficits
D. None of the above
Patients present with severe vertigo, nausea, and vomiting, but no accompanying hearing loss or other CNS deficits
- Cause:*
- Edema of the Vestibular nerve or ganglion; some patients report a recent viral infection preceeding the development*
Which of the following correctly describes Vestibular Schwannoma? What causes this disorder?
A. Triggered by specifc changes in body motion like turning over in bed that causes brief episodes of vertigo
B. Patients present with hearing loss (100% of the time), gait difficulties (70%), and tinnitus (70%)
C. Patients present with severe vertigo, nausea, and vomiting, but no accompanying hearing loss or other CNS deficits
D. None of the above
Patients present with hearing loss (100% of the time), gait difficulties (70%), and tinnitus (70%)
- Cause:*
- A benign tumor that came from Schwann cells of the vestibular root impinges on structures going through the internal acoustic meatus (CN7, CN8, Labyrinthine A.)*
Lateral Vestibulospinal Tract originates from the lateral and inferior vestibular nuclei and projects tp the ipsilateral spinal cord on the anterorostral and posterocaudal areas. What is the function of this tract?
Control of extensors on the ipsilateral side for maintaining posture
What is the purpose of the vestibulocolic reflex?
What vestibulospinal tract is it related to?
Stabilize the head by activating neck musculature
Medial Vestibulospinal Tract
The Medial Vestibulospinal Tract receives integrated input from vestibular receptors, the cerebellum and what very important ascending tract?
PCMLS
Which of the following correctly expresses the path and function of the Medial Vestibulospinal Tract?
A. Fibers descend ipsilaterally through the Medial Longitudinal Fasciculus and terminate in the cervical spinal cord to stabilize neck flexors and extensor musculature
B. Fibers descend contralterally through the Medial Longitudinal Fasciculus and terminate in the cervical spinal cord to stabilize neck extensors and extensor musculature
C. Fibers descend bilaterally through the Medial Longitudinal Fasciculus and terminate in the cervical spinal cord to stabilize neck extensors and flexor musculature
D. Fibers descend bilaterally through the Medial Longitudinal Fasciculus and terminate in the cervical spinal cord to stabilize neck flexors and extensor musculature
Fibers descend bilaterally through the Medial Longitudinal Fasciculus and terminate in the cervical spinal cord to stabilize neck flexors and extensor musculature
All vestibular nuclei project to what complex?
Ventral Posterior Nuclear Complex
Thalamic nuclei function to relay vestibular input for processing of motion and body orientation and the third order neurons target the following cortical areas. A lesion in which of the following locations would cause vertigo, unsteadiness, and loss of ‘visual vertigo’?
A. Primary Somatosensory Cortex
B. Parietoinsular Vestibular Cortex
C. Posterior Parietal Cortex
D. None of the above
Parietoinsular Vestibular Cortex
Thalamic nuclei function to relay vestibular input for processing of motion and body orientation and the third order neurons target the following cortical areas. A lesion in which of the following locations would result in confusion in spatial awareness?
A. Primary Somatosensory Cortex
B. Parietoinsular Vestibular Cortex
C. Posterior Parietal Cortex
D. None of the above
Posterior Parietal Cortex
What is the function of the THalmocortical Pathways?
Processing of motion and body orientation
What is the vestibuloocular Reflex?
What’s an example of when it’s used?
Counter rotation of the eyes that allows our bodies to stabilize images during head movement
Looking at a sign while running
Vestibulooccular Reflex (VOR) has a slow phase and a fast phase. The combo of the slpw phase and punctuated fast phase is called what?
How is this action type named?
Nystagmus
- named for the fast phase
Describe the pathway of the VOR as it occurs during head rotation to the right
- Fluid movement in the right semicu=ircular duct
- Increased activation of the right afferent fibers, and inhibition of left affernt fibers
- Right afferent fibers stimulate right vestibular nuclei
- Secondary fibers activate the left CN 6 nucleus and right CN 3 nucleus via MFL
- Lateral rectus activates in the left eye and medial rectus in the right eye activates
What causes spontaneus Nystagmus?
Unilateral damage to the vestibular system
How do you tell the difference between peripheral damage or central damage that results in sponatneous nystagmus?
Peripheral damage will only result in spontaneus nystagmus, while Central damage we will also see other eye movement errors
NOTE: peripheral damage is to the vestibular labyrinth and or CN 8
The CAloric test is a short-term test that is used to determine vestibular dysfunction. Using warm or cold water, we are able to simulate head turning (via convection currents on endolymph) and test for the VOR reflex.
Warm water results in nystagmus in what direction?
Cold water results in nystagmus in what direction?
Warm water is same side nystagmus
Cold water is opposite side nystagmus
T/F: The Oculocephalic Reflex (also called the doll’s eye maneuver) is a compensatory reflex that occurs when the head moves causing eyes to move in the opposite direction of the head. The Head thrust test, looks at this reflex and is used on comatose patients to determine if the brainstem is intact. If there is a lesion in the brainstem, would the doll’s eye reflex be present or absent?
Reflex would be absent
Look at it again
To test for a brainstem lesion we will utilize the caloric test, and use warm water in the right ear. Which of the following would you likely see when there is a bilateral lesion of the Medial Longitudinal Fasciculus?
A. During slow phase the Left Lateral rectus activated but right medial rectus absent
B. During slow phase the Right Lateral rectus activated but left medial rectus is absent
C. During slow phase neither the lateral rectus nor medial rectus is activated
D. During slow phase the left lateral rectus is inhibted and the left medial rectus is activated
During slow phase the Left Lateral rectus activated but right medial rectus absent
