13 Motor Systems - M

Question 1

Which Brodmann’s area is associated with the primary motor cortex?

Answer 1

area 4

Question 2

Neurons from which spinal tracts arise from the primary motor cortex and associated motor cortices?

Answer 2

Corticospinal tract (CST) and corticonucleus system

Question 3

What type of neurons arise from the motor cortices?

Answer 3

UMNs

Question 4

How is the motor homunculus organized?

Answer 4

Question 5

Where do CST fibers cross?

Answer 5

pyramidal decussation in the medulla

Question 6

What side of the body is innervated by the L primary & associated motor cortices?

Answer 6

The R side of the body

Question 7

A lesion in the CST tract rostral/superior to the medulla pyramids results with hemiparesis or hemiplegia on what side of the body?

Answer 7

contralateral side of lesion b/c lesion is before decussation

Question 8

A lesion of the CST caudal/inferior to the medulla pyramids results in hemiparesis on which side of the body?

Answer 8

ipsilateral side b/c lesion is after decussation

Question 9

Fibers of the corticonuclear tract project where?

Answer 9

to the motor nuclei of CNs in the midbrain, pons & medulla

Question 10

What are the only two groups of head/facial muscles to receive contralateral innervations instead of bilateral innervation by UMNs of the Corticonucleus system?

Answer 10

lower facial muscles & genioglossus muscle

Question 11

The lateral corticospinal tract supplies what type of muscles?

Answer 11

appendicular muscles (muscles of extremities)

Question 12

The anterior corticospinal tract supplies what type of muscles?

Answer 12

axial muscles (muscles of the trunk)

Question 13

Which part of the corticospinal tract does not cross to the contralateral side?

Answer 13

The anterior CST

Question 14

After leaving the motor cortices what structures do the UMNs axons of the CST pass through in the telencephalon?

Answer 14

corona radiata –> posterior limb of internal capsule

Question 15

What do UMNs of the CST code for/ what is their effect on LMNs?

Answer 15

encode for required force & direction of movement

Question 16

What brain systems/regions are important for the activation of the appropriate response to a stimulus?

Answer 16

Cerebellum, Basal nuclei, thalamus, and primary/supplemental sensory cortices

Question 17

What is Brodmann area 6?

Answer 17

supplementary motor cortex

Question 18

What cortical region plans the muscular movements and what executes the plan

Answer 18

• supplementary motor cortex (area 6) = plans
• primary motor cortex (area 4) = executes

Question 19

UMNs from which motor cortex project to the reticular activating system to form the reticulospinal fiber/tract?

Answer 19

supplementary motor cortex

Question 20

What structure is located at the anteromedially most part of the striatum

Answer 20

Nucleus accumbens

Question 21

What structures lies superomedially to the internal capsule?

Answer 21

caudate nucleus

Question 22

What structures lie lateral to the internal capsule?

Answer 22

Lentiform nucleus (globus pallidus and putamen) of the basal nucleus

Question 23

What structure lies directly medial to the putamen?

Answer 23

globus pallidus

Question 24

What structure lies directly lateral to the globus pallidus?

Answer 24

putamen

Question 25

What is the function of the putamen?

Answer 25

subconscious muscular movement (i.e. posture)

Question 26

What is the function of the caudate nucleus?

Answer 26

patterned movements associated w/ walking (remember cycle?)

Question 27

What is the function of the globus pallidus?

Answer 27

* adjusts muscle tone * (influences UMNs' modulatory effects on LMNs)

Question 28

What are the 5 major nuclei of the basal nuclei/ganglia?

Answer 28

1. caudate nucleus 2. nucleus accumbens 3. globus pallidus 4. putamen 5. substantia nigra

Question 29

What is the most ventral part of the midbrain?

Answer 29

substantia nigra (posterior to cerebellar peduncle but anterior to the tegmentum)

Question 30

What are the 2 parts of the substantia nigra?

Answer 30

pars compacta and pars reticulate

Question 31

What is the main site of input into the substantia nigra?

Answer 31

pars compacta

Question 32

What part of the substantia nigra houses neurons that contain melanin and make dopamine?

Answer 32

pars compacta

Question 33

What do the pars compacta due with the dopamine it makes?

Answer 33

projects to and supplies the caudate and putamen with dopamine

Question 34

What is the function of the pars reticulate?

Answer 34

projects to other brain regions

Question 35

What nucleus is the pars reticulate a functional homolog of?

Answer 35

globus pallidus (medial segment)

Question 36

What are the 2 pathways of the basal nucleus?

Answer 36

direct and indirect pathways

Question 37

What is the function of the direct basal nucleus pathway?

Answer 37

increases activity of the thalamus = increases cerebral activity

Question 38

What is the function of the indirect pathway of the basal nucleus?

Answer 38

inhibits the direct pathways = decreases thalamic activity

Question 39

Pallidothalamic fibers are GABAergic neurons that are apart of which basal nuclear pathway?

Answer 39

indirect pathway b/c that inhibit thalamic activity

Question 40

GABAergic neurons typically do what?

Answer 40

act as inhibitory neurons = decreasing activity of target cells

Question 41

What is the subthalamic fasciculus?

Answer 41

a bidirectional pathway between the subthalamus and globus pallidus

Question 42

Function of the subthalamic fasciculus when the direct pathway is active?

Answer 42

pallidosubthalamic fiber (GABAergic) inhibit subthalamic cells = blocks inhibition of thalamus

Question 43

Function of the subthalamic fasciculus when the indirect basal pathway is active?

Answer 43

pallidosubthalamic fibers are inhibited = activation of suthalamopallidal fibers (Glutamate) --\> activation of pallidothalamic fiber (GABAergic fibers --\> inhibits thalamus activity

Question 44

What are nigro-thalamic fibers?

Answer 44

non-dopaminergic fibers from pars reticulars --\> thalamus

Question 45

Where do nigro-thalamic fibers terminate?

Answer 45

ventroanterior and ventrolateral thalamic nuclei

Question 46

What are nigro-striatal fibers?

Answer 46

dopaminergic fibers from pars compacta

Question 47

Name the fibers and part of the substantia nigra that are destroyed in Parkinson's disease?

Answer 47

Nigro-striatal fibers from the pars compacta

Question 48

What nuclei comprise the dorsal (corpus) striatum?

Answer 48

caudate nucleus & putamen

Question 49

What type of fibers are striatonigral fibers?

Answer 49

GABAergric (inhibitory)

Question 50

What is the path of striatonigral fibers?

Answer 50

putamen --\> par compacta of substantia nigra & globus pallidus

Question 51

What is the path of nigro-striatal fibers?

Answer 51

substantia nigra --\> striatum (caudate & putamen)

Question 52

What damage to what structure is most commonly associated with Parkinson's disease?

Answer 52

pars compacta of substantia nigra w/in the basal nucleus

Question 53

What would be some signs of Parkinson's disease?

Answer 53

* shuffling gait * tremoring limbs at rest * akinesia * bradykinesia * disrupted eye movements * loss of postural reflexes

Question 54

When do Huntington's Disease symptoms begin?

Answer 54

35-44yrs of age

Question 55

Loss of what fibers are associated with Huntington's disease?

Answer 55

striatonigral fibers (GABAergic) = inhibit pars compacta of substantia nigra

Question 56

Why would the loss of striatonigral fibers lead to Huntington's disease?

Answer 56

Loss of inhibition of substantia nigra --\> overactivation of the corpus striatum = loss of cognitive coordination

Question 57

What is Sydenham's chorea?

Answer 57

Childhood autoimmune disease that disrupts the neuronal activity of basal nucleus

Question 58

What is a major manifestation of rheumatic fever?

Answer 58

Sydenham's chorea

Question 59

What is ballismus?

Answer 59

uncontrolled flinging (ballistic movement) of limbs

Question 60

How does ballismus typically present?

Answer 60

as hemiballismus

Question 61

What is chorea?

Answer 61

rapid, irregular involuntary, dance-like movements that flow randomly from one body region to another

Question 62

What diseases can chorea be seen with?

Answer 62

* Huntington disease * tardive dyskinesia * treatment of Parkinson's disease * rheumatic fever

Question 63

What is athetosis?

Answer 63

the continuous writhing of distal portions of one or more extremities

Question 64

What nuclei receive UMNs from corticonuclear fibers?

Answer 64

* motor nuclei of CN 5, 7, 12 * nucleus ambiguus (CNs 9 and 10) * accessory nucleus (CN 11)

Question 65

UMN lesions of CN 7 lead to what type of facial paralysis?

Answer 65

central facial paralysis (central 7) = drooping of contralateral lower lip

Question 66

LMN lesions of CN 7 lead to what type of facial paralysis?

Answer 66

Bell (facial) palsy = flaccid paralysis of upper and lower facial muscles on the ipsilateral side

Question 67

UMNs lesions of nucleus ambiguus leads to damage in motor neurons from what nerves?

Answer 67

CNs 9 and 10

Question 68

Damage to UMN going to the CN 10 part of nucleus ambiguus leads to what? * R UMNs --\> L nucleus ambiguus --\> \_\_\_\_

Answer 68

deviation of plate/uvula towards lesion/away from the damaged nerve R UMNs --\> L nucleus ambiguus --\> **weak uvula on L = deviation** **to** **R.**

Question 69

Damage of R UMNs to the L hypoglossus motor nucleus results in what?

Answer 69

loss of Left (contralateral) hypoglossus nerve = tongue protrudes to left

Question 70

Damage to LMNs from the hypoglossus motor nucleus or root of the hypoglossus nerve results in what?

Answer 70

weakness and deviation of tongue to side of lesion

Question 71

What other tract runs in close association to the corticonuclear tract?

Answer 71

corticospinal tract (CST)

Question 72

occlusion or hemorrhage of what artery would result in a lesion to corticonuclear tract as it passes through the internal capsule?

Answer 72

lenticulostriate/thalamostriatal artery from the MCA.