Lp 9

Question 1

-motor cortices
-SC
-a motor system
-y motor system

Answer 1

Motor control

Question 2

-control contraction of IFFs & frequency of m spindle firing
-increase frequency of m spindle firing; increase reflex contraction of m
-increase y neuron activity leads to increase m shortening before returning to resting state

Answer 2

Y motor neurons

Question 3

-precise control of m contraction & relaxation
-up SC tracts to cerebellum
-cerebellum adjusts firing rate to mm via y neuron system & apprises cerebrum (via thalamus)

Answer 3

CNS control of y activity

Question 4

Decrease excitability of stretch reflex, leading to decrease m contraction

Answer 4

Hypotonia

Question 5

Increase excitability of motor pathways
*results in stiffness, paresis, spastic paralysis

Answer 5

Hypertonia

Question 6

Increase Ia discharge vis IFF contraction facilitates EFF contraction

Answer 6

Agonist mm

Question 7

Inhibited by decrease firing (less likely to respond), leads to decrease opposition to movement

Answer 7

Antagonist

Question 8

-trigger: changes in environment
-structures: sensory receptors & ascending pathways
Effects: sensation & perception

Answer 8

Sensory stimulation

Question 9

-trigger: sensory input at cortical level
-structures: cerebral cortex, descending pathways, effectors
-effects: motor behaviours

Answer 9

Motor stimulation

Question 10

Levels of motor integration

Answer 10

-programs & instructions,
-protection
-segmental

Question 11

-neuronal circuits n cerebellum & basal nuclei
-location of sensory & motor integration
-Fxn:
*start & stop movements
*coordinates movements
*block unwanted movements
*monitor m tone & posture

Answer 11

Pre-command areas

Question 12

-sensorimotor integration
-receives proprioception & cerebral input
*allows coordinated movement & balance
-does not project to SC or motor cortex
*reaches them indirectly via brain stem & thalamus respectively

Answer 12

Cerebellum

Question 13

Regions of cerebellum

Answer 13

-vermis (middle region)

-intermediate region

Question 14

Controls axial & girdle mm via vestibular & reticular nuclei

Answer 14

Vermis (middle region)

Question 15

Controls distal limb mm via cerebral cortex & red nucleus

Answer 15

Intermediate region

Question 16

-do not receive sensory input directly
-do not project directly onto motor tracts
-receive input from all cortical areas
-send impulses to motor cortices (thalamus links)
-form complex excitatory & inhibitory connections:
*w/each other
*subthalamic nucleus
*substatia nigra

Answer 16

Basal nuclei

Question 17

Sequence:
-motor cortex (intent to perform movement)
-pre-command areas (initiate responses)

Pathway:
-motor cortex (UMNs) send activating signals to segmental motor neurons
-LMNs (a-motor) excite m fibres

Answer 17

Basal nuclei

Question 18

-controls segmental motor activity of SC
Structures:
*cortical motor areas (pyramidal tracts)
*brain stem nuclei (extra-pyramidal system)
-facilitate reflex & fixed-pattern action
-axons project into SC-form the 2 systems of descending motor tracts

Answer 18

Projection level

Question 19

Projection levels?

Answer 19

Pyramidal (direct) system axons
Extra-pyramidal (indirect) structures

Question 20

-synapse on segmental interneurons & LMNs
-branch out to basal nuclei, cerebellum & motor nuclei of brain stem
-terminate on a-motor neurons
*inerevate distal mm of fine motor coordination

Answer 20

Pyramidal (direct) system axons

Question 21

-cortical motor areas forming pyramidal tracts
-brain stem nuclei controlling the extra-pyramidal system

Answer 21

Extra-pyramidal (indirect) structures