S2 Neuro Exam 4: Corticofugal Motor Systems

Front 1

Obj.
What are the motor associated areas of the cerebral cortex?

Back 1

-primary motor cortex (area 4 & ant paracentral lobule)
-premotor & supplementary area (areas 6 & 8)

Front 2

Where do the motor associated areas send output?

Back 2

corticospinal & corticonuclear tract

Front 3

Neurons that give rise to the corticospinal tract arise mostly from where?

Back 3

layer V of cerebtral cortex

-includes Betz cells in precentral gyrus/primary motor cortex w/ direct contact w/ spinal cord alpha motor neurons

Front 4

The primary motor cortex (M1) in Brodmann's are 4 & the ant paracentral lobule is somatotopically organized.
Describe the somatotopical contribution to motor activity

Back 4

Disproportionate size of body parts represents density & distribution of axons to muscle groups in regions

(legs near paracentral lobule, face & tongue near frontal operculum adjacent to lateral fissure)

Front 5

How does the somatotopical contribution of the premotor cortex (M2) differ from M1?

Back 5

direct corticospinal projections have less precise somatotopic destinations

*stimulation may elicit one muscle, bilateral, etc movement

Front 6

The coticospinal & corticonuclear tracts leave the cerebral cortex through the ____________ & rotate as they enter the genu & posterior limb of the internal capsule.
Where do the head & body regions end up?

Back 6

corona radiata


head axons are in genu, arms are medial & legs are lateral

Front 7

The ____________ tract gives off collaterals to areas not directly related to motor control, including the;
inferior olivary complex,
posterior column nuclei,
& medullary reticular nuclei

Back 7

corticospinal tract

Front 8

Corticospinal fibers from the ___________ terminate in the intermediate zone & anterior horn (laminae VII-IX)

Back 8

frontal lobe

Front 9

Corticospinal fibers from the ___________ terminate in the base of the posterior horn (laminae IV-VI)

Back 9

parietal lobe

Front 10

The cortiospinal tract is ______ biased w/ terminating excitatory interneurons

Back 10

Flexor biased


(some inhibitory interneurons contact antagonist extensors)

Front 11

Corticonuclear axons terminate on what motor nuclei?

Back 11

CN III
CN IV
CN VI
XII
XI
X
IX
VII
V

Front 12

Corticonuclear axon termination patterns to non-ocular motor nuclei (NOT III, IV, or VI) are mostly_________________

Back 12

predominantly crossed w/ some bilateral

Front 13

____________ & ______________ tracts affect muscle tone & less discrete motor aspects (posturing of trunk & proximal limbs)

Back 13

rubrospinal & reticulospinal tracts

(reticulospinal & red nucleus are directly influenced & have some independent activity)

Front 14

How are layers of neurons in the motor cortex arranged?

Back 14

series of vertical columns associated w/ similar functions (same muscle, etc)

*can provide direct feedback to neurons performing motor functions

Front 15

What is a long-latency reflex?

Back 15

a small area of primary motor cortex can evoke flexion of a digit-->
same digit receives sensory stimuli & sends somatosensory feedback-->
feedback received by same area (column of cells) that initiated the motor responsed

Front 16

T/F
A particular muscle may be regulated by more than one cortical location

Back 16

TRUE

Front 17

During a planned movement both _______ & M1 (primary motor cortex) are activiated, while in a random movement only M1 is involved

Back 17

M2 (supplementary motor cortex, area 6)

Front 18

When a planned movement is rehearsed mentally but NOT carried out which area is activated?

Back 18

M2 ONLY

(thus M2= planning, M1= execution of movement)

Front 19

The __________ lies rostral to the anterior part of M1 & receives primary input from sensory areas of the parietal cortex, then projects the M1, spinal cord, & reticular formation.

Back 19

premotor cortex

Front 20

The premotor cortex is involved in _____________

Back 20

preparation to move

Front 21

Obj
what are the non-motor areas of cortex associated w/ motor activity?

Back 21

-primary sensory cortex (areas 3, 1, 2, post paracentral)
-associational cortex (superior parietal lobule, 5 & 7)
-cingulate gyrus

Front 22

Area 5 (posterior parietal cortex) recieves projections from ___________& vestibular input

Back 22

somatosensory cortex

Front 23

Area 7 (posterior parietal cortex) processes info related to what?

Back 23

location of objects in space

Front 24

Areas 5 & 7 both project primarily where?

They perform processing for making movements related to what?

Back 24

supplementary & premotor cortexes

movement in space related to reaching a visual target

Front 25

T/F

Along with the previously mentioned areas, the cingulate gyrus is somatotopically organized

Back 25

FALSE

cingulate gyrus is NOT somatotopically organized

Front 26

The cingulate gyrus & sulcus project where?

What are they involved in?

Back 26

primary motor cortex


motivation for movements, specifically emotion motivation

Front 27

Describe parallel motor processing


Which areas are involved in this?

Back 27

Parietal, supplementary, & premotor cortex

--> multiple projection pathways to spinal cord & brainstem provide indirect motor influence, in addition to direct influence of premotor cortex