Neurology (01/26) Descending Motor Systems

Question 1

primary muscle disease

Answer 1

myopathies (occur in the muscle fibers)

Question 2

innervates striated muscle, directly signals muscle to contract, only way movement can be initiated

is the LAST NEURON in chain of neurons

Answer 2

lower motor neuron

Question 3

motor neurons that deal with extrafusal muscle fibers

Answer 3

alpha motor neurons

Question 4

motor neurons that deal with intrafusal muscle fibers

Answer 4

gamma motor neurons

Question 5

five types of lower motor neuron lesions

Answer 5

• atonia
• areflexia
• flaccid paralysis
• fasciculations
• atrophy

Question 6

lower motor neuron lesion that is a loss of muscle tone

Answer 6

atonia

Question 7

lower motor neuron lesion that is a loss of myotatic (knee jerk) reflex

Answer 7

areflexia

Question 8

lower motor neuron lesion where the muscle becomes limp and just “sits” there

Answer 8

flaccid paralysis

Question 9

lower motor neuron lesion that causes spontaneous muscle contractions (you can see them, they look like twitches)

Answer 9

fasciculations

Question 10

lower motor neuron lesion that is a loss of muscle tissue

Answer 10

atrophy

Question 11

neurons whose axons descend from cortex and end on or near lower motor neurons

Answer 11

Upper motor neurons

Question 12

what are the 4 types of upper motor neuron lesions?

spastic paralysis

Answer 12

• hypertonia
• hyperreflexia
• pathologic reflexes
• big toe dorsoflexion

Question 13

upper motor neuron lesion that causes increased resting tension and makes it difficult for patients to move arms and legs

Answer 13

hypertonia

Question 14

upper motor neuron lesion that deals with the fanning of toes when the side of the heal is stroked

Answer 14

big toe dorsiflexion

Question 15

in upper motor neurons, is atrophy severe or mild?

Answer 15

mild

Question 16

in lower motor neurons, is atrophy severe or mild?

Answer 16

severe

Question 17

during a routine exam you note that the patient has tongue fasciculations. this raises concern for?

Answer 17

lower motor neuron injury

Question 18

in lower motor neurons, the cell bodies are in the _____ horn

Answer 18

anterior

Question 19

in lower motor neurons, the axons in ______ root divide into terminal branches widely distributed in target muscle

Answer 19

ventral

Question 20

in lower motor neurons, each branch ends at one _______ ______

Answer 20

neuromuscular junction

Question 21

in lower motor neurons arrangement in the spinal cord, the neurons controlling axial muscles are _____ to those controlling distal muscles

Answer 21

medial

Question 22

in lower motor neurons arrangement in the spinal cord, neurons controlling flexors are located _____ to the extensor group

Answer 22

posterior

Question 23

1 motor neuron + all myofibers it innervates

Answer 23

motor unit

Question 24

T/F all motor units are similar in size

Answer 24

false

Question 25

in motor units, does the motor nerve actually innervate every myofiber?

Answer 25

no, it is scattered throughout

Question 26

what are the three types of muscle fibers

Answer 26

- standing - running - jump

Question 27

type of muscle fiber that contracts weakly for long periods

Answer 27

standing

Question 28

type of muscle fiber that contracts strongly for short/long periods

Answer 28

running

Question 29

type of muscle fiber that contract very strongly for very short periods

Answer 29

jump

Question 30

each muscle fiber type populates one _____ ____. aka no mixing

Answer 30

motor unit

Question 31

which type (1 or 2) of muscle fiber is used for sustained force weight bearing?

Answer 31

1

Question 32

which type (1 or 2) of muscle fiber is used for sudden movements in purposeful motion

Answer 32

2

Question 33

which type (1 or 2) of muscle fiber has an abundant amount of lipids?

Answer 33

1

Question 34

which type (1 or 2) of muscle fiber has a scant amount of lipids

Answer 34

2

Question 35

which type (1 or 2) of muscle fiber has a scant amount of glycogen

Answer 35

1

Question 36

which type (1 or 2) of muscle fiber has an abundant amount of glycogen?

Answer 36

2

Question 37

which type (1 or 2) of muscle fiber has many mitochondria?

Answer 37

1

Question 38

which type (1 or 2) of muscle fiber has very few mitochondria

Answer 38

2

Question 39

which type (1 or 2) of muscle fiber is involved with slow twitch

Answer 39

1

Question 40

which type (1 or 2) of muscle fiber is involved with fast twitch

Answer 40

2

Question 41

which type (1 or 2) of muscle fiber did the teacher say has a "duck breast muscle"

Answer 41

1

Question 42

which type (1 or 2) of muscle fiber did the teacher say has a "turkey breast muscle"

Answer 42

2

Question 43

_____ _____ and ______ influence cerebral cortical output to cord and brainstem but everything must first go through the _____

Answer 43

- basal ganglia - cerebellum - thalamus

Question 44

basal ganglia, cerebellum, and associated cortex are vital in design, choice, and monitoring of movement, but note they have NO direct effect on ______ ______ ______

Answer 44

lower motor neurons

Question 45

does damage to the basal ganglia or cerebellum areas cause weakness?

Answer 45

no, but there may be involuntary movements, incoordination, and difficulty initiating movements

Question 46

as far as deciding what movement should occur, the _______ cortex plans and tells the ______ cortex what to do which is then relayed to the _____ _____ _____

Answer 46

- premotor - motor - lower motor neurons

Question 47

basal ganglia and cerebellum are involved in planning and monitoring movements by effecting the ____ and _______ cortexes

Answer 47

- motor | - premotor

Question 48

where are the two places that most descending motor pathways terminate on?

Answer 48

- dorsal horn neuons | - interneurons on the dorsal horn

Question 49

tract that goes from cortex to spinal cord and is considered a classic upper motor neuron. some fibers to hand region of cord terminate on primary motor neurons in anterior horn

Answer 49

corticospinal tract (pyramidal tract)

Question 50

tract that goes from cortex to brainstem

Answer 50

corticobulbar (corticoneuclear) tract

Question 51

tract that goes from cortex to basilar pons

Answer 51

corticopontine tract

Question 52

what are the 5 origins of the corticospinal tract?

Answer 52

- primary motor area (40%) - somatic sensory area (25%) - premotor area (20%) - supplementory motor area (10%) - superior parietal lobe (5%)

Question 53

what numbers are included in brodmann area?

Answer 53

312

Question 54

area 4 on the medial and lateral aspect, its functions are the execution of contralateral voluntary movements (crosses the medulla) and control of fine digital movements.

Answer 54

primary motor area

Question 55

the primary motor area projects to what two places?

Answer 55

- brainstem | - spinal cord

Question 56

a lesion of the primary motor cortex causes what?

Answer 56

paralysis of contralateral musculature

Question 57

what are the three functions of the premotor area?

Answer 57

- plan movements (response to external cues) - control of proximal and axial musculature (trunk, shoulder, hip) - assembles empathetic facial movements

Question 58

the premotor area projects to where?

Answer 58

primary motor area and reticular formation

Question 59

a lesion of the premotor area causes what two things?

Answer 59

- moderate weakness of contralateral proximal muscles | - loss of ability to associate learned hand movements to verbal or visual cues

Question 60

what is the function of the supplementary motor area? (medial aspect of area 6)

Answer 60

plans movements while thinking (assembles new sequence) (assembles previously learned sequence) ("imagines" movements)

Question 61

what two places does the supplementary motor area project to?

Answer 61

- premotor area | - primary motor area

Question 62

the division of the parietal lobe that projects to the primary motor area is responsible for what?

Answer 62

directing motor patterns in response to sensory input

Question 63

the division of the parietal lobe that projects to the sensory areas of the brainstem and spinal cord is responsible for what?

Answer 63

modulate sensory signals

Question 64

if the corticospinal tract is cut in monkeys, after a period of _____ _____, they move again, but fine ______ movement is lost permanently

Answer 64

- flaccid paralysis | - finger

Question 65

are all movement dependent on the corticospinal tract?

Answer 65

no (remember the monkeys) other paths can become active and take over the functions

Question 66

what two places does the corticospinal tract originate from?

Answer 66

- precentral gyrus | - cerebral cortex

Question 67

where does the corticospinal tract decussate?

Answer 67

spinomedullary junction

Question 68

in the corticospinal tract, 85% of the fibers cross in decussation in medulla and descend in _____ _____

Answer 68

lateral funiculus

Question 69

in the corticospinal tract, 15% of fibers remain uncrossed and descend in _____ _____

Answer 69

anterior funiculus

Question 70

in the corticospinal tract, some of the fibers regarding ____ muscle activity cross in the anterior _______ prior to synapsing

Answer 70

- axial | - commissure

Question 71

what are the 4 less important pathways that the professor just wants us to know exist

Answer 71

- rubospinal tract - reticulospinal tract - vestibulospinal tract - tectospinal tract

Question 72

less important tract that is in control of shoulder and proximal arm

Answer 72

rubospinal tract

Question 73

less important tract that is in control of axial musculature - walking

Answer 73

reticulospinal tract

Question 74

less important tract that is in control of axial musculature - balance

Answer 74

vestibulospinal tract

Question 75

less important tract that is believed to be important in head turning reflexes in response to visual stimuli, has an unclear function in humans

Answer 75

tectospinal tract

Question 76

where is the origin of the corticobulbar pathway?

Answer 76

face/mouth portion of motor cortex and other nearby areas

Question 77

the corticobulbar pathway descends with the corticospinal tract to the level of the target nucleus, then splits off so no ______ _______ exists

Answer 77

corticobulbar decussation

Question 78

in the corticobulbar pathway, the _____ face is bilateral, and the _____ face is ipsilateral.

Answer 78

- upper | - lower

Question 79

unilateral damage to the corticobulbar pathway results in what?

Answer 79

inability to smile or show teeth symmetrically | the ability to wrinkle forehead is unaffected