motor control part 1

Question 1

greater than 1/2 of the primary motor cortex controls what?

Answer 1

hands and speech

Question 2

what area is anterior to the lateral portions of primary motor cortex below supplemental area?

Answer 2

premotor area

Question 3

the premotor area projects to?

Answer 3

1 degree motor cortex and basal ganglia

Question 4

what area is superior to premotor area lying mainly in the longitudinal fissure?

Answer 4

supplemental motor area

Question 5

what movements do the premotor and supplemental motor areas provide?

Answer 5

attitudinal movements
fixation movements
positional movements of head and eyes
background for finer control of arms/hands

Question 6

what percentage of the corticospinal tract originates in the primary motor cortex?

Answer 6

30%

Question 7

what percentage of the corticospinal tract originates in the premotor and supplemental areas?

Answer 7

30%

Question 8

what percentage of the corticospinal tract originates in the somatic sensory areas?

Answer 8

40%

Question 9

where does the corticospinal tract descend?

Answer 9

via the posterior limb of the internal capsule (btw caudate and putamen)

Question 10

what does the corticospinal tract form?

Answer 10

pyramids of the medulla

Question 11

when corticospinal tract fibers cross midline they form?

Answer 11

lateral corticospinal tract

Question 12

when corticospinal fibers stay ipsilateral they form?

Answer 12

ventral corticospinal tract

Question 13

when all tracts are cut and the cord is completely isolated from the brain its called? Low

Answer 13

spinal preparation

flaccidity!

Question 14

when you have a transection at the mid collicular level mid brainstem its called?

Answer 14

decerebrate preparation

rigidity!

Question 15

destruction of the cerebral cortex/ high brain stem is called?

Answer 15

decorticate preparation

different type of rigidity- spasticity

Question 16

which brainstem area that receives stimulation from the vestibular nuclei and transmits excitatory signals to stimulate the axial trunk and extensor muscles that support the body against gravity?

Answer 16

pontine reticular nuclei

Question 17

which brainstem area that receives strong input from the cortex, red nucleus, and other motor pathways and transmits inhibitory signals to the same antigravity muscles via the medullary (lateral) reticulospinal tract

Answer 17

medullary reticular nuclei

Question 18

with regard to postural control, if DESCENDING cortical signals are blocked, what is the expected result?

Answer 18

increased extensor tone, flexors repressed- decerebrate rigidity

Question 19

what is the function of a dynamic signal from pyramidal cells to alpha motor neurons?

Answer 19

initiation of muscle contraction

Question 20

what is the function of static signal from pyramidal cells to alpha motor neurons?

Answer 20

fires at a slower rate to maintain contraction after initiation has occurred

Question 21

what some important characteristics of postural reflexes?

Answer 21

• impossible to separate from voluntary movements
• they maintain body in an upright position
• maintain stable postural background for voluntary movement

Question 22

extension of the neck facilitates extensors of?

Answer 22

arms and legs

Question 23

flexion of the neck facilitates flexors of?

Answer 23

arms and legs

Question 24

rotation of the neck facilitates extensors ______ and inhibits flexors ______

Answer 24

ipsilateral; ipsilateral

Question 25

rotation of the neck facilitates flexors ______ and inhibits extensors _________

Answer 25

contralateral; contralateral

Question 26

at the onset of clockwise rotation (to the right) what would you expect happens in the VIII cranial nerve on the left side?

Answer 26

decrease in firing rate

Question 27

stimulation of semicircular canals is associated with?

Answer 27

increased extensor tone | nystagmus

Question 28

slow component- tracking nystagmus is initiated by

Answer 28

semicircular canals

Question 29

fast component- jumping ahead nystagmus is initiated by

Answer 29

brain stem nuclei

Question 30

after 20 clockwise rotations with eyes closed on a revolving stool, the subject is abruptly stopped and the eyes are opened. what is observed?

Answer 30

lateral nystagmus with slow component clockwise

Question 31

what are 3 disorders involved with the basal ganglia?

Answer 31

tremor and other involuntary movements changes in posture and muscle tone poverty and slowness of movement

Question 32

motor functions of the basal ganglia are mediated by the?

Answer 32

motor areas of the cortex

Question 33

what are the 2 circuits of the basal ganglia?

Answer 33

caudate | putamen

Question 34

caudate + putanem =

Answer 34

striatum

Question 35

what is a lesion in the globus pallidus?

Answer 35

athetosis- spontaneous and continuous writhing movements

Question 36

what is a lesion in the subthalamus?

Answer 36

hemiballismus- sudden violent and flailing movements

Question 37

what is multiple small lesions in putamen?

Answer 37

chorea- flicking movements in hands and feet

Question 38

rigidity, akinesia and resting tremors happen in?

Answer 38

substantia nigra- Parkinsons

Question 39

in backward sway, what is the distal to proximal sequence of muscles?

Answer 39

tibialis- quad- abdominal

Question 40

in forward sway, what is the distal to proximal sequence of muscles?

Answer 40

gastrocnemius- hamstring- paraspinals

Question 41

what would happen to a repetitive simple stretch reflex, if when a muscle contracts it destabilizes posture?

Answer 41

it would be inhibited

Question 42

what would happen to a repetitive simple stretch reflex, if when a muscle contracts it stabilizes posture?

Answer 42

it would be facilitated

Question 43

ones sense of upright is generally a combination of cues that include both visual and vestibular information, true or false?

Answer 43

true- CN VIII connected to CN III, IV, VI

Question 44

what effect does the striatum have on the substantia nigra?

Answer 44

inhibitory GABA projections

Question 45

a stroke that lesions the posterior limb of the internal capsule (between putamen and caudate) would be associated with?

Answer 45

loss of voluntary movement

Question 46

when supine, head tilt is best detected by what?

Answer 46

saccule

Question 47

what plays an important role in determining orientation of the head when person is upright?

Answer 47

utricle

Question 48

what plays an important role in determining orientation of the head when person is lying down?

Answer 48

saccule

Question 49

signals from neck proprioceptors typically OPPOSE signals from the vestibular apparatus as the head and neck are rotated and have similar effects on limb flexion and extension. true or false?

Answer 49

true