Lecture 4: Coordination and Vestibular System Flashcards
What is main function of cerebellum?
coordinates and regulates posture, movement and balance
What is main function of brainstem?
integrates and sorts sensory information
What is sequence to perform coordinated movement or balance?
- sensory input (vestib, visual, proprio)
- integration of input (brainstem, cerebellum)
- motor output
- balance
What is coordination?
smooth, accurate and controlled movement which involves sequence, timing and force production
What does normal coordination look like?
promixal fixation for distal control, postural control, easy and and off and fluid
What is intralimb coordination?
occuring with one limb
What is interlimb coordination?
integrated performance of two or more limbs
What is visual motor coordination?
ability to integrate both visual and motor abilities
aka hand eye coordination
What are key brain structures used for coordination?
motor cortex, descending motor tracts, basal ganglia, cerebellum
What does motor cortex and descending pyramidal pathways do?
for trunk and proximal control, anticipatory control, initiation
What does basal ganglia do?
regulate initiation and gross intentional movements
regulate complex planning and execution
How much of CNS neurons does cerebellum contain?
50 %
What cerebellar nuceli are responsible for motor execution?
fastigal and interposed
What cerebellar nuclei are responsible for motor planning?
denate
What cerebellar nuclei are responsible for balance and eye movements?
vestibular nuclei
What is the vermis for?
postural control
What are main cerebellar functions?
coordinate range, velocity and strength of muscle contractions to produce steady volitional movements
What are other cerebellar functions?
equilibrium, muscle tone regulation, eye head coordination, coordination for muscle of speech
comparator- corrects errors of movement
comensator
What type of system is cerebellar functions?
closed loop
What is ataxia?
cerebellar pathology that results in disordered movement, difficulty initiating volitional movement
errors in rate, rhytym and timing of muscle
What side does ataxia occur on?
ipsilateral side of lesion
What is etiology of ataxia?
congenital, acquired (strokes, tumors, trauma)
What is most common sign of cerebellar lesion?
ataxic gait, decreased arm swing, uneven step length, increased BOS, high movement variability
What is dysdiadochokinesia?
decreased rapid alternating movements, antagonistic muscle firing over powers agonist
flipping hand back and forth
What is dysmetria?
deficit in reaching a target, overshooting a target when pointing
What is dyssynergia?
breaking down movement into unsmooth motion
What is an intention tremor?
oscillation of limb with volitional movement, most pronounced with end of movement
What is role of vestibular system?
critical in control of posture, where are we in relation to gravity, proprioception, sensing and perceiving motion, gaze stability
What are two components of peripheral apparatus?
bony labrinth and membranous labyrinth
What makes up the bony labyrinth?
- three semi circular canals
- cochlea
- vestibule
What makes up membranous labyrinth?
membranous portions of 3 semicircular canals as well as utricle and saccule
filled with endolymph -resembles intracellular fluid
What do the semicircular canals do?
detect angular head rotation and respond to angular acceleration, provide sensory input about head velocity
What are key anatomical features of semicircular canals?
the ampulla- contain hair cells
the christa ampullaris
the cupula
endolymph
What is otoliths and what does it do?
refer to utricle (horizontal) and saccule (vertical)
detect linear acceleration and static head tilt, sensitive to gravity
What are hair cells?
sensory receptors made up of kinocillia and stereocillia
What causes the hair cells to move?
caused by motion of endolymph
stereo towards kino- excitation
stereo away from kino- inhibition
How are cerebellum and vestibular system connected?
cerebellum is calibration of vestibular system, without proper functioning cerebellum then vestibular reflexes are ineffective
What are two mechanisms for motor output?
VOR- vestibulo ocular
VSR- vestibulo spinal reflex
What CNS structures are associated with VOR and VSR?
VOR- medial longitudinal fasiculus
VSR- lateral and medial vestibulospinal tracts
What is the VOR?
maintains stable vision/ gaze stability during head motion, look left eyes go right
one of fastest reflexes in body
What is VOR gain?
ratio of eye movements to head movement amplitude
normally equals 1.0
What is VSR?
stabilizes body by using otolithic input, stabilizes body before a fall
strong influence on posture, postural control and stability
What is Cervico ocular reflex?
supplements to VOR, driven by neck receptors
What is vestibulocollic reflex?
acts on neck musculature to stabilized head
What are clinical signs of vestibular dysfunction?
veering towards sign of lesion, nausea, vertigo, dizziness, diplopia, nystagmus
What are two categories of coordination testing?
non- equilibrium and equilibrium
What are some non equilibrium tests?
finger to nose, finger opposition, pronation/supination, pointing, heel to shin, tapping (DF/PF)
What are equilibrium tests for coordination?
tandem stance, perturbations, romberg, walking on heels
What can you document during these test?
number of trials, patient position, reps done in 10 seconds, eyes open or closed
With any coordination dysfunction what do you also need to test for?
sensory deficits- proprio, kinesthesia, vibration, sterognosia
dysfunction can cause sensory ataxia which is worse with eyes closed then cerebellar with eyes closed
