Biological Basis of Equilibrium disorders block 18 2011.ppsx
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Transcript of Biological Basis of Equilibrium disorders block 18 2011.ppsx
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Vision - external reference
Primary organ of equilibrium: Vestibular system internal reference
Somatosensory internal & external reference
Brain
Information about the body's position
Skeletal muscles
Postural adjustment BALANCE
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Information about the body's position
If the brain receives inadequate information about the body's position
dysequilibrium
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Otolith organs Utricle Sacculus
Semicircular canals Superior Posterior Horizontal
Vestibular organ
Linear acceleration of the head
Rotational acceleration of the head
Static tilt
Gravitationforce
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Otolith organs Utricle: horizontal
Sacculus: vertical
Linear acceleration of the head
Lateral vestibular nuclei
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AmpullaeSemicircular canals
Rotational acceleration of the head
Semicircular Canals
Superior
Posterior
Horizontal
Medial vestibular nuclei
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The semicircular canals detect angular acceleration. There are 3 canals, corresponding to the three dimensions in which you move, so that each canal detects motion in a single plane. The actual hair cells sit in a small swelling at the base called the ampula
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Rotation around y axis
Rotation around x axis
Translationalx,y,z axes
otolith organs
Rotational
semicircular canals
Rotation around z axisVestibular Navigation
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Scarpa ganglion
Vestibular nuclei
Ventral posterior nucleus complex of thalamus
both sides
Vestibular cortex(Posterior parietal cortex)
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Connections underlying the
vestibulo-ocular reflex
initiates compensatory eye movement
keep the eyes focused on a target during head movement
Scarpa’s ganglion
Midbrain
Pons
Rostral medullaMedial vestibular nucleusCaloric test
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Balance – Anxiety links
Hypothalamus, amygdala, limbic cortexAnxiety
Parabrachial nucleus
somatic & visceral sensory Vestibular nuclei Spinal cord
Balance
ANS control
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• Peripheral / otological – 85% (NIH); Indonesia?– ototoxic drug, infections,
vestibular neuroma, head trauma or natural aging process
• Central– central vestibular system,
psychogenic
Vertigo
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Cerebellum: coordination
Medial Vestibular nucleus
Mid-Pons
Rostral Medulla
Spinal cord
Descending projections from vestibular nuclei to the spinal cord Vestibulocervical Vestibulospinal reflexes
Lateral Vestibular nucleus
Vestibular nuclei receive inputs from cerebellum
Motor cortex
Somatosensory
