neural control of balance and movement

Question 1

define centre of gravity

Answer 1

the point about which the mass is evenly distributed

Question 2

what information does the vestibular system provide?

Answer 2

information gravitational, linear, and angular accelerations of the head with respect to inertial space

Question 3

what is the role of the vision in neural control of balance and movement?

Answer 3

measures orientation of eyes and head in relation to surrounding objects

Question 4

what is the role of the somatosensory system?

Answer 4

provides information concerning relative position of body parts; measures touch, pressure, temperature, pain and proprioception

Question 5

what is meant by balance?

Answer 5

the ability of the body to achieve equilibrium

Question 6

what are the proprioceptors in humans?

Answer 6

muscle spindles within skeletal striated muscle, and golgi tendon organs within tendons

Question 7

what does the leminiscal pathway do?

Answer 7

relay information from proprioceptors to spinal cord to cortex

Question 8

what is the role of the lateral cortical spinal tract?

Answer 8

responsible for voluntary movement of distal muscles, controlled by the cortex

Question 9

where does the the lateral cortical spinal tract decussate?

Answer 9

cervicomedullary junction

Question 10

what is the rubrospinal cord responsible for?

Answer 10

large muscle movement and fine motor control

Question 11

what does the location of termination of the rubrospinal cord suggest?

Answer 11

it teminates in the cervical spinal cord, which suggests it functions in the upper limb but not lower limb control

Question 12

what is the tecto-spinal cord responsible for?

Answer 12

co-ordination of head and eye movements

Question 13

what is the reticulo-spinal tract responsible for?

Answer 13

autonomic posture and gait related movements

Question 14

what is the role of the vestibulo-spinal tract?

Answer 14

the lateral and medial tracts are responsible for increasing antigravity muscle tone in response to the head being tilted to one side

Question 15

what do the semicircular canals do?

Answer 15

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

Question 16

what type of movement do the semicircular canals detect?

Answer 16

head rotation

Question 17

what type of movement do the utricle and saccule detect?

Answer 17

linear head rotation

Question 18

what is the utricle sensitive to?

Answer 18

changes in horizontal regulation

Question 19

what is the saccule sensitive to?

Answer 19

changes in vertical acceleration

Question 20

list the three main vestibular reflexes

Answer 20

1) vestibulo-ocular reflex
2) vestibulo-collic reflex
3) vestibular-spinal reflex

Question 21

what does the vestibulo-ocular reflex do?

Answer 21

keeps the eyes still in space when the head moves

Question 22

what does the vestibulo-collic reflex do?

Answer 22

keeps the head still in space or on a level plane during walking

Question 23

what does the vestibular-spinal reflex do?

Answer 23

adjusts posture for rapid changes in movement

Question 24

what are the functions of the midbrain?

Answer 24

visual + auditory processing and reflexes, fine tuning of voluntary movements

Question 25

what are the functions of the pons?

Answer 25

relay station for the cerebellum

control of sub-conscious movement

Question 26

how is the vestibular system involved in regulation of equilibrium during exercise?

Answer 26

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

Question 27

what happens when signals are sent to the vestibular nuclei?

Answer 27

changes to tone and contractility of the axial and proximal limb muscles

Question 28

what is the role of the superior colliculus of the midbrain when stimulated?

Answer 28

coordinates eye movement with head movements during exposure to acceleration, maintains clear vision

Question 29

how is the cerebellum involved with motor learning during exercise?

Answer 29

cerebellar circuits learn to make movement more accurate after repetition, over time, the successive steps of the motor act become more precise

Question 30

how is the cerebellum involved with coordination of movement during exercise?

Answer 30

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

Question 31

what is the role of the vermis?

Answer 31

principle region of the cerebellum associated with postural adjustment

Question 32

how does the vermis regulate posture?

Answer 32

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