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Describe the tree types of sensory input:
______: Can be viewed as a motor skill that emerges from the interaction of multiple systems. Describe the three components.
- Steadiness, Symmetry, Dynamic stability
______ system: Provides information concerning gravity, rotation and acceleration. Contributes to integration of arousal,conscious awareness of the body via connections with vestibular cortex and reticular formation
Influence from the ________ pathway mediate nausea and vomiting.
______ system: allows for gaze and postural stability; sense of orientation; detection of linear and angular acceleration.
______ ______ _____: detects and relays info about head angular and linear velocity to central processing system. Orients the head with respect ot gravity.
Peripheral sensory apparatus
_____ _____ ____: processes info in conjunction with other sensory inputs for position and movement of head in space.
central processing system
____ ____ ____: generates compensatory eye movements and compensatory body movements during head and postural adjustments.
motor output system
The peripheral apparatus is composed of
- Membranous labyrinth
- semicircular canals
- otolith organs
______ ______: responsible for angular acceleration and ampulla contains sensory epithelium.
The spatial arrangement of the 6 SSC causes __ coplanar pairings. What are they?
3: R and L lateral; L anterior and R posterior; L posterior and R anterior; R and L horizontal
The 3 coplanar pairings all for the ___-____ arrangement.
What are the 3 advantages of SSC coplanar pairing.
- sensory redundancy
- common mode rejection/mode
- assist in compensation for sensory overload
What are the three structures of the Otoliths (utricle and saccule):
- otolithic membrane
_____ function: respond to linear head motion on acceleration; static tilt; two organs respond to respective accelerations or tilts in their respective planes.
_____: vertical orientation of maculae. linear accelerations/deceleration in vertical plane. Tilting head toward lateral plane. Sensitive to low frequency vibration.
_____: horizontal orientation of maculae. Respond to acceleration/deceleration in horizontal plane. Head movements toward ventral or dorsal planes.
What are the two types of hair cells?
What are there functions?
- kinoclium and stereocilia
- Sensory structures for the peripheral end organs (maculae and ampulla)
- Hyperpolarized or depolarized depending upon the direction of deflection of the stereocilia (movement of stereocilia towards the kinocilium causes depolarization of the hair cell)
- Affect the firing rate of the primary vestibular afferents to the brainstem
_____ of macula: serves as structural landmark. Contains otoconia arranged in narrow trenches, dividing each otolith. Orientation of the hair cells change over the course of the macula. Allows otoliths to have multidirectional sensitivity.
____ ____ ____:
• Vestibular nerve and vestibular nuclei have anormal resting firing rate (70-100 cycles/sec)
• Baseline firing rate present without headmovement• Tonic firing is equal in both sides; if not, asense of motion is felt e.g., vertigo, tilt,impulsion, spinning
• Excitation and inhibition of the vestibularsystem can then occur from stimulation of thehair cells
Tonic Firing Rate
• Depolarization of the ipsilateral hair cellsoccurs during angular head movements
• Hyperpolarization of contralateral hair cellsoccurs at the same time
• Hair cells are only able to hyperpolarize towhat they were at rest = cut off of inhibitoryinfluences from the movement going in theopposite direction even if the ipsilateral haircells continue to spike higher firing rates
_____ _____ ____:
• Perseveration of neural firing in the vestibularnerve by the brainstem after stimulation ofSSC to increase time constant (10sec.)– SSC respond by producing anexponentially decaying change in neuralfiring to sustained head movement
• Otolith & somatosensory input also drivemechanism
Velocity Storage Mechanism
____ ____ ____:
• Causes eyes to move in the oppositedirection to head movement
• Speed of the eye movement equals that ofthe head movement
• Allows objects to remain in focus duringhead movements
Vestibular Ocular Reflex
____ _____ ____:
• Keeps eye still in space while head ismoving
• Ratio of eye movement to head movement(equals 1)
Vestibular Processing Gain
______: – Connection with vestibular cortex and reticularformation → arousal and conscious awarenessof body; discrimination between self movementvs. that of the environment
– Junction of parietal and insular lobe
– Target for afferents along with the cerebellum
• Monitors vestibular performance
• Readjusts central vestibular processingof static & dynamic postural activity
• Modulates VOR
• Provides inhibitory drive of VOR (allowsfor VORcancellation)
• Provide motor output from the vestibularsystem to:
– Extraocular muscles (part of VOR)
– Spinal cord & skeletal muscles (generateantigravity postural activity to cervical,trunk & lower extremity muscles)
______ ______: Generates compensatory body movementto maintain head and postural stability,thereby preventing falls
_____ ______: Maintains head stability during active headon body movement
Progressive changes of vestibular system begin at age __.
______: primary diagnostic indicator in identifying vestibular lesions. Rapid alternating movements of eyes.
_____ _____ ____: postural sway is measured during 6 different sensory conditions. Performance patterns may guide expectations for certain diagnoses.
Sensory Organization Test
Vestibular disorders are secondary only to ___ ___ pain.
The NIH estimates ____% of the population over ___ years of age will experience a dizziness disorder during their life time.
- low back pain
- 40 years of age
Progressive changes of vestibular system begin at age ___. Decreased number of hair cells. Decreased vestibular nerve fibers. Lead to dizziness and vertigo.
_____ nystagmus: vestibular rotary, visual, etreme lateral gaze.
_____ nystagmus: spontaneous, positional, gaze evoked.
- Physiologic nystagmus
- Pathologic Nystagmus
____ ____: direction of gaze will shift with the head movement. Cause degradation of the visual image. In severe cases, visual world will move with each movement.
____: asymmetrical firing of the two vestibular systems. Gives an illusion of spinning movement.
______: visual illusion of oscillating movement of stationary objects. Can arie with lesions of peripheral or central vestibular systems.