neural control of balance and movement Flashcards
define centre of gravity
the point about which the mass is evenly distributed
what information does the vestibular system provide?
information gravitational, linear, and angular accelerations of the head with respect to inertial space
what is the role of the vision in neural control of balance and movement?
measures orientation of eyes and head in relation to surrounding objects
what is the role of the somatosensory system?
provides information concerning relative position of body parts; measures touch, pressure, temperature, pain and proprioception
what is meant by balance?
the ability of the body to achieve equilibrium
what are the proprioceptors in humans?
muscle spindles within skeletal striated muscle, and golgi tendon organs within tendons
what does the leminiscal pathway do?
relay information from proprioceptors to spinal cord to cortex
what is the role of the lateral cortical spinal tract?
responsible for voluntary movement of distal muscles, controlled by the cortex
where does the the lateral cortical spinal tract decussate?
cervicomedullary junction
what is the rubrospinal cord responsible for?
large muscle movement and fine motor control
what does the location of termination of the rubrospinal cord suggest?
it teminates in the cervical spinal cord, which suggests it functions in the upper limb but not lower limb control
what is the tecto-spinal cord responsible for?
co-ordination of head and eye movements
what is the reticulo-spinal tract responsible for?
autonomic posture and gait related movements
what is the role of the vestibulo-spinal tract?
the lateral and medial tracts are responsible for increasing antigravity muscle tone in response to the head being tilted to one side
what do the semicircular canals do?
when the head turns in the plane of the semicircular canal, the inertia of the endolymph produces a force across the cupula, distending it away from the direction of head movement and causing a displacement of the hair bundles
what type of movement do the semicircular canals detect?
head rotation
what type of movement do the utricle and saccule detect?
linear head rotation
what is the utricle sensitive to?
changes in horizontal regulation
what is the saccule sensitive to?
changes in vertical acceleration
list the three main vestibular reflexes
1) vestibulo-ocular reflex
2) vestibulo-collic reflex
3) vestibular-spinal reflex
what does the vestibulo-ocular reflex do?
keeps the eyes still in space when the head moves
what does the vestibulo-collic reflex do?
keeps the head still in space or on a level plane during walking
what does the vestibular-spinal reflex do?
adjusts posture for rapid changes in movement
what are the functions of the midbrain?
visual + auditory processing and reflexes, fine tuning of voluntary movements
what are the functions of the pons?
relay station for the cerebellum
control of sub-conscious movement
how is the vestibular system involved in regulation of equilibrium during exercise?
vestibular receptors send sensory signals to the cerebellum, which initiate corrective signals to be sent to the vestibular nuclei and superior colliculus of the midbrain
what happens when signals are sent to the vestibular nuclei?
changes to tone and contractility of the axial and proximal limb muscles
what is the role of the superior colliculus of the midbrain when stimulated?
coordinates eye movement with head movements during exposure to acceleration, maintains clear vision
how is the cerebellum involved with motor learning during exercise?
cerebellar circuits learn to make movement more accurate after repetition, over time, the successive steps of the motor act become more precise
how is the cerebellum involved with coordination of movement during exercise?
the cerebellum corrects the movements
when motor areas of cerebral cortex sends motor commands to muscles, cerebellum receives an immediate copy of the intended motor command via the cortico-ponto-cerebellar pathway and the ventral spinocerebellar tract
as the movement proceeds, the cerebellum receives proprioceptive signals about motor performance via spino-cerebellar tract
what is the role of the vermis?
principle region of the cerebellum associated with postural adjustment
how does the vermis regulate posture?
receives sensory information from muscle and joint proprioceptors concerning position of the body. its output controls the vestibulospinal and reticulospinal tracts that regulate tone and contraction of limb muscles
