Exam II

Question 1

Which corticospinal tract fibers form the ventral corticospinal tract?

Answer 1

ipsilateral fibers

Question 2

Which corticospinal tract fibers form the lateral corticospinal tract ?

Answer 2

contralateral fibers

Question 3

What percentage of the corticospinal tract fibers originate from areas behind the central sulcus, including the primary somatosensory cortex?

Answer 3

40%

Question 4

Greater than 1/2 of the primary motor cortex is devoted to control of what?

Answer 4

the hands and mouth

Question 5

What percentage of the corticospinal tract fibers originate from areas in front of the central sulcus?

Answer 5

60% = 30% primary motor cortex + 30% premotor and supplemental areas

Question 6

A stroke that lesions the posterior limb of the internal capsule would be associated with a loss of what?

Answer 6

voluntary movement

Question 7

A high brain stem lesion results in what?

Answer 7

spasticity

Question 8

A middle brain stem lesion results in what?

Answer 8

rigidity

Question 9

A low brain stem lesion results in what?

Answer 9

flaccidity

Question 10

List the ipsilateral tracts

Answer 10

ventral corticospinalreticulospinalvestibulospinal

Question 11

List the contralateral tracts

Answer 11

lateral corticospinalrubrospinaltectospinal

Question 12

list the 5 descending pathways

Answer 12

ventral/lateral corticospinalreticulospinalvestibulospinalrubrospinaltectospinal

Question 13

the reticulospinal tract is made up of what two formations?

Answer 13

pontine (medial) reticular formationmedullary (lateral) reticular formation

Question 14

What muscles does the vestibulospinal tract mainly innervate?

Answer 14

extensors

Question 15

What muscles does the rubrospinal tract mainly innervate?

Answer 15

flexors

Question 16

What movement is the superior colliculus mainly involved with?

Answer 16

orienting reactions

Question 17

motor cortex = ?

Answer 17

primary + supplementary + premotor

Question 18

supplemental motor cortex control

Answer 18

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

Question 19

high cut =

Answer 19

decorticate spasticity

Question 20

mid cut =

Answer 20

decerebrate rigidity

Question 21

low cut =

Answer 21

flaccidity

Question 22

decorticate spasticity: loss of cortical inhibition of ?

Answer 22

gamma efferent discharge via the medullary reticular nuclei

Question 23

decorticate spasticity is the result of a ?

Answer 23

stroke (60% of cases have affected internal capsule arteries)

Question 24

superior/inferior colliculi are located on what side of the brain stem?

Answer 24

dorsal