Test 3 - Descending Motor Systems

Front 1

Lower motor neurons are also known as _______ ________ neurons.

Back 1

alpha motor - somatic efferent

Front 2

What is the paleocerebellum also known as?

Back 2

Anterior lobe, spinocerebellum

Front 3

What is the neocerebellum also known as?

Back 3

posterior lobe or cerebral cerellum

Front 4

What is the archicerebellum also known as?

Back 4

flocculonodular lobe, or vestibulocerebellum

Front 5

What are the capabilities/functions of interneurons?

Back 5

crossed, uncrossed, inhibit, faciliatate, internuncial (connect two neurons in a pathway).

Front 6

The anterior horn of the spinal cord contains alpha motor neurons. within this horn the neurons responsible for FLEXORS are found ________ (ventrally/dorsally) and the EXTENSORS are found (ventrally/dorsally).

Back 6

flexors -dorsal.
extensors - ventral

Front 7

Within the anterior horn the alpha motor neurons are organized by flexors/extensors, gamma/alpha motor neurons, and what body part they are innervate, this is called ____________ organization.

Back 7

somatotopic

Front 8

The organization of the innervation of limbs/trunk in the anterior horn of the spinal cord is _______ more laterally and __________- more medially.

Back 8

Hands (outermost extremities) and Trunk more medially.

Front 9

What horn is the substantia gelatinosa found in? Is it more dorsal or ventrally located within that horn?

Back 9

In the gray matter of the posterior/dorsal horn. It is located more dorsally in the dorsal horn.

Front 10

What is more laterally found in the anterior horn? The gamma efferents or the alpha efferents?

Back 10

Gamma

Front 11

Gamma motor neurons innervate _______-- muscle fibers. Alpha motor neurons innervate ___________ muscle fibers.

Back 11

intrafusal, extrafusal

Front 12

The Voluntary motor System, also known as the pyramidal system originates where?

Back 12

In the cortex of the precentral gyrus in the brain (area 4).

Front 13

Where are pyramidal cells found? what do pyramidal cells in the precentral gyrus project to and what is their function?

Back 13

in the cortex of the brain (gray matter) - They travel down the internal capsule, through the cerebral peduncles of the midbrain, through the anterior aspect of the pons, become the pyramids of the medulla and decussate (pyramidal decussation) in the caudal medulla and then enter the spinal cord (lat. corticospinal tract or ant. corticospinal tract). They then enter in the anterior horn and synapse on a lower motor neuron (alpha motor neuron).

Front 14

Where does pyramidal decussation occur?

Back 14

Caudal Medulla - identify on brain slice.

Front 15

T/F The lateral corticospinal tract is somatotopically organized.

Back 15

TRUE

Front 16

What is found more laterally in the lat. corticospinal tract? What is found more medially?

Back 16

Lower extremities - laterally, upper extremities - medially (Trunk inbetween the two)

Front 17

Where does the anterior corticospinal tract decussate?

Back 17

In the spinal segment of innervation - via the anterior white commissure.

Front 18

Does the lateral corticospinal tract utilize axon collaterals to activate neurons in other spinal levels?

Back 18

yes

Front 19

If the lateral corticospinal tract is severed and the innervation doesn't occur to a particular lower motor neuron, can the muscle that the LMN innervates ever regain function?

Back 19

the functional property is still there but the more exterior is harder to gain back, don't get back fine skill motor mvt. You can only regain that limited mvt. because of the plethora of innervations from other tracts (rubrospinal, reticulospinal, vestibulospinal, etc...)

Front 20

T/F Hemisection does NOT wipe out voluntary control of sphincters (bladder and anus).

Back 20

TRUE, because of bilateral innervation by the anterior corticospinal tract.

Front 21

What percentage of corticospinal fibers are crossed? (pyramidal decussation)

Back 21

90%

Front 22

What percentage of corticospinal fibers remain ipsilateral, yet bilaterally innervate muscles of the trunk?

Back 22

10% - anterior corticospinal tract.

Front 23

________ is a fiber that originates in the motor cortex and ands on a lower motor neuron, (either directly or by way of an interneuron).

Back 23

Upper motor neuron

Front 24

Upper motor neurons travel though what tract?

Back 24

Corticospinal

Front 25

If you damage an UMN (upper motor neuron) what symptoms/lesion will you see?

Back 25

spastic paralysis, hyperreflexia, no muscle atrophy, abnormal reflexes.

Front 26

If you damage a LMN what deficits will you see in the muscle it innervates?

Back 26

FLaccid paralysis, hyPOreflexia, muscle atrophy, fasciculations.

Front 27

T/F the cerebellum initiates motor activity.

Back 27

FALSE the cerebellum DOES NOT initiate motor activity.

Front 28

What structure in the brain controls ongoing motor activity? (strength, timing accuracy)

Back 28

Cerebellum

Front 29

What type of innervation does the cerebellum receive?

Back 29

Sensory (proprioception) Via the spinocerebellar tract.

Front 30

T/F the cerebellum is active during cognition, memory, and pain association too.

Back 30

True

Front 31

What are the convolutions called that help increase the surface area of the cerebellum.

Back 31

arbor vitae "tight organization"

Front 32

The cerebellum is known as the "little brain" it has ________ surface area of cerebral cortex but as many _________ as the rest of the brain.

Back 32

3/4, neurons.

Front 33

How many layers are found in the cerebellar cortex? Is this considered old brain or new brain?

Back 33

3 layers - old brain. 6 layers is the highest number you can get and is present in the cerebral cortex.

Front 34

What lobe of the cerebellum is the 'tonsil' a part of? where foramen is located by?

Back 34

Posterior lobe, It is the foramen magnum, if it herniates through it can compress the medulla.

Front 35

What fissure separates the ant. lobe from the post. lobe?

Back 35

primary fissure

Front 36

What fissure separates the flocculonodular lobe from the posterior lobe?

Back 36

posterolateral fissure

Front 37

Through what structure does the cerebellum communicate through?

Back 37

Cerebellar peduncles on the posterior surface of the brainstem.

Front 38

There are 3 cerebellar peduncles, The inferior cerebellar peduncle is visible in what section of the brain stem?

Back 38

Rostral medulla

Front 39

What information is carried through the inferior cerebellar peduncle?

Back 39

Afferents from spinal cord and brainstem SOME efferent to spinocerebellars for fine tuning. The pathway traveling through is called the reflex proprioception pathway (posterior spinocerebellar tract) for upper extremities it synapses on the accessory cuneate nucleus and then travels through the inferior cerebellar peduncle to end up in the cerebellum. info stays ipsilateral - no crossing over.

Front 40

What information travels through the middle cerebellar peduncle?

Back 40

Afferents from pontine nuclei (contralateral). - impulses from the brain that come from the cortex to the pons (corticopontine) and then synapse on pontine nuclei and those neurons send axons (pontocerebellar) to the cerebellum via the middle cerebellar peduncle. (the info crosses over in the pons so comes in contralateral)

Front 41

T/F The middle cerebellar peduncle ONLY carries INPUT.

Back 41

True. no output

Front 42

What information is carried through the superior cerebellar peduncle?

Back 42

Output to Red nucleus and thalamus - SOME input (ventral spinocerebellars - reflex proprioception pathway).

Front 43

T/F the superior cerebellar peduncle with where you find the BIGGEST outflow from the cerebellum.

Back 43

TRue

Front 44

Name the lobe. receives sensory information from vestibular system. Functions to maintain equilibrium.

Back 44

archicerebellum, (flocculonodular lobe) Vestibulocerebellum

Front 45

Name the lobe. receives sensory info. from muscle, tendon and spindles via spinal cord tracts. Regulates muscle tone and synergy in trunk musculatrue and limb girdles, expecially for automatic movements (walking, standing, posture).

Back 45

Paleocerebellum (spinocerebellum, anterior lobe)

Front 46

Name the lobe. receives sensory info. from motor regions of the cerebral cortex via pontine nucle and middle cerebellar peduncle. mostly related to skilled, learned movements with the hands and hand-eye coordination (especially for voluntary movements.)

Back 46

Neocerebellum (lateral hemisphere, posterior lobe, cerebral cerebellum)

Front 47

If you lesion the Anterior lobe/spinocerebellar tracts/vermis (paravermal or intermediate region) where will the lesion present?

Back 47

Trunk and Legs - unconscious proprioception, Posture.

Front 48

What lesion and where will it present if you damage the cortex, pontinocerebellar fibers, or posterior lobe?

Back 48

decrease in skilled motor mvts. (hands)

Front 49

What lesion and where will it present if you damage the flocculonodular lobe?

Back 49

Loss of balance - Trunk only (remember that ANTERIOR lobe lesion effects trunk AND legs)

Front 50

What forms the main output from the cerebellum?

Back 50

cerebellar nuclei (fastigial, interposed, and dentate)

Front 51

What lobe is associated with the Fastigial nuclei?

Back 51

Flocculonodular lobe (vestibular system)- same symptoms would result if deep nuclei was damaged as if the lobe was damaged.

Front 52

What lobe is the interposed nuclei associated with?

Back 52

Spinocerebellar tracts, Unconscious proprioception - Anterior lobe. (which includeds the vermal, paravermal regions - paleocerebellum).

Front 53

What two nuclei comprise the interposed nuclei?

Back 53

Globose and Emboliform

Front 54

What lobe is associated with the dentate nuclei?

Back 54

Posterior Lobe - (neocerebellum) - pontinocerebellar fibers - cerebral cerebellum.

Front 55

____________ cells are the only neurons that leave the cerebellar cortex. They are always ________ (inhibitory/excitatory).

Back 55

Purkinje, Inhibitory

Front 56

Where do climbing fibers originate?

Back 56

In the inferior olivary nucleus. (in the medulla)

Front 57

What peduncle do climbingfibers travel through?

Back 57

Inferior cerebellar peduncle.

Front 58

What is the ratio of climbing fibers to purkinje cells?

Back 58

1:1

Front 59

What do Spinocerebellar, Pontinocerbellar, Vestibular nuclei and sensory input become in the cerebellum? (what type of neuron/fiber)

Back 59

Mossy fiber.

Front 60

What do mossy fibers synapse on and in what layer?

Back 60

On Granule cells in the granular layer.

Front 61

Where are purkinje cells found? what layer of the cerebellar cortex?

Back 61

In the purkinje layer.

Front 62

Where are the dendrites of the purkinje cell found?

Back 62

Molecular layer.

Front 63

What do granule cells synapse on and in what layer?

Back 63

on parallel fibers in the granular layer - THEn they project to teh molecular layer.

Front 64

What do parallel fibers synapse on and in what layer?

Back 64

On purkinje dendrites in the molecular layer.

Front 65

Do purkinje cells send an inhibitory or excitatory message?

Back 65

INHIBitory.

Front 66

What is the ratio of parallel fibers to purkinje cells.

Back 66

LOTS: 1

Front 67

What does the purkinje cell synapse on?

Back 67

Deep nuclei of the cerebellum.

Front 68

Where does the major output of the deep nuclei project to? via what peduncle?

Back 68

To motor system via the superior cerebellar peduncle.

Front 69

T/F the climbing fibers from the olives to the cerebellar cortex cross the midline.

Back 69

True

Front 70

What artery supplies the superior cerebellum (anterior lobe)

Back 70

basilar Artery. (runs along basilar sulcus of pons). -> SUPERIOR CEREBELLAR ARTERY>

Front 71

What artery supplies the Lateral hemisphere of the cerebellum (post. lobe)?

Back 71

a branch off of the basilar artery AICA (anterior inferiro cerebellar artery).

Front 72

What artery supplies the Flocculonodualr lobe - posterior region of cerebellum.

Back 72

A branch off of the vertebral artery (vertebral is the result of the splitting of the basilar) PICA (posterior inferior cerebellar artery).

Front 73

What fibers/neurons are excitatory in the cerebellum.

Back 73

ALL but purkinje

Front 74

What input going into the cerebellum is the only input capable of bypassing the cerebellar cortex and synapsing on the deep nuclei?

Back 74

Input from the: spinocerebellar, cuneocerebellar, spinoreticular, mesencdphalic cerebellar..all synapsing on the interposed nuclei AND the input via the vestibulocochlear nerve to the fastigial nuclei.

Front 75

Where does the output from the fastigial nucleus end up?

Back 75

Vestibular Nucleus -> two places 1. vestibulospinal tract to LMN, and Medial Longitudinal fasciculus to CN 3,4,6. Reticular formation -> reticulospinal tract -> LMN = upright balance.

Front 76

All of the output/input of the fastigial nucleus leaves/enters via the ______ peduncle.

Back 76

inferior

Front 77

T/F Balance is cortical ascending.

Back 77

FALSE, thus the vestibulocerebellum doesn't relay messages to the cerebral cortex

Front 78

T/F Every lobe in the cerebellum recieves at least SOME input from the inferior olivary nucleus.

Back 78

TRue

Front 79

T/F The loop that occurs from the reticular formation to the interposed nucleus is mainly for getting rid of "junk."

Back 79

True

Front 80

What lobe of the cerebellum is responsible for posture, synergy, timing, accuracy of ongoing movements, (especially of the trunk and limb girdles).

Back 80

Spinocerebellum Paleocerebellum anterior lobe

Front 81

What input does the cortex of the anterior lobe and interposed nucleus receive?

Back 81

from sensory info from golgi tendon organ, etcs...from the spinocerbellar, cuneo - spinoreticular - and mesencephalic cerebellar tracts.

Front 82

What does the interposed nucleus project to and via what peduncle?

Back 82

Brain stem reticular formation (activating reticulospinal tracts) the vestibular nuclei (activating vestibulospinal tracts) all via the inferior cerebellar peduncle. to the red nucleus and thalamus via the superior cerebellar peduncle. THe reticulo and vestibulo paths synapse on gamma motor neurons in the anterior horn of the spinal cord.

Front 83

Where does the red nucleus project to? and what is it's purpose?

Back 83

To the inferior olivary nucleus (ipsilaterally) and to LMN (alpha) via the rubrospinal tract (contralaterally).

Front 84

What lobe of the cerebellum is associated with: skilled learned movements, especially hand and hand-eye coordination unique volitional movements, smooth sequential movement with appropriate strength and precision.

Back 84

Posterior lobe, neocerebellum, cerebral cerebellum, pontocerebellum.

Front 85

Where does the post. lobe of the cerebellum receive it's input from?

Back 85

Mainly from pontocerebellar fibers from the pontine nuclei (activated from corticopontine fibers from the cortex). Travel via the middle cerebellar peduncle to the cortex of the cerebellum. From the inferior olivary (originally from the cortex via the pyramidal tract - branched off to olives) nucleus via climbing fibers. (contralateral input to post. lobe.

Front 86

What is the main output of the dentate nuclei?

Back 86

To the Red Nucleus, which then activates thalamus - > cortical activation. or goes to LMN or corticobulbar.

Front 87

What tract does information from the dentate travel through, also what structure does it pass through?

Back 87

the dentatorubrothalamic tract via the superior cerebellar peduncle.

Front 88

______ co-operation or co-ordination in muscle action.

Back 88

synergy

Front 89

___- range, direction, amplitude and force of muscle contraction are inappropriate. Dysmetria and dysdiadochokinesia result from asynergy in muscle groups.

Back 89

dyssynergy (asynergy)

Front 90

___ an asynergic disturbance in which there is a distortion of voluntary and associated movements. Involves particularly the axial muscles and muscles around the shoulder and pelvic girdles. Disturbance is evident in walking, gait is broad-based and patient reels, lurches and stumbles. There is frequently unsteadiness in standing especially if the feet are close together and eyes are closed.

Back 90

ataxia (dystaxia)

Front 91

_________ of movement - because of asynergy in muscle groups movements are separated into several puppet-like movements.

Back 91

decomposition

Front 92

__ loss of ability to gauge the distance, speed or power of a movement, eg. when reaching out with the finger to an object the finger overshoots the mark or deviates from it (overshoot or past-pointing), or the movement may be stopped before the goal is reached.

Back 92

dysmetria

Front 93

________ - decrease (loss) of muscle strength; muscles tire easily and there may be slowness in movements.

Back 93

hypoasthenia (asthenia)

Front 94

________ - muscle flaccidity with decrease in resistance to passive movement of the joints.

Back 94

hypotonia

Front 95

----------- rapid alternating movements, eg. flexion and extension of fingers to pronate and supination of forearm

Back 95

dysdiadochokinesia

Front 96

tremor not seen at rest but become evident on purposeful movement. Best observed in upper extremity (weight bearing masks in lower extremity) and it becomes more evident as the hand approaches its objective (terminal tremor).

Back 96

intention tremor (action tremor).

Front 97

What lobe is damaged if these symptoms are seen: trunkal disequilibrium - gait and trunk affected
walk on wide base
trunk sways when walking and is unsteady when standing
stagger - appears drunk
Same sympt. occurwhen either of these structures are damaged as well:
cerebellopontine angle tumor
lateral medullary syndrome

Back 97

Flocculonodular lobe or archicerebellar lesions.

Front 98

What lobe is damaged:
specifically related to alcoholism or malnution
symptoms appear as gross deficits, mainly affecting trunk AND legs
most prominent signs include: dystaxia (ataxia) - poor coordination of muscles of gait and stance. legs uncoordinated, dystaxia (ataxia) of trunk - trunk bobs to and fro

Back 98

anterior lobe or paleocerebellum lesion or if superior cerebellar artery

Front 99

what lobe is damaged:
often unilateral
maycombine with anterior lobe and vermal symptoms
lesion of cerbellar hemisphere, dentat nucleus (AICA) or superior cerebellar peduncle. (dentatorubrothalamic tract)
also affects speech and eye movement
aymptoms most obvious in UPPER extremities - rapid find mvts.

Back 99

posterior lobe, neocerebellum, cerebral cerebellum, lateral hemisphere lesion (all same thing, just many names...)

Front 100

What is a way to distinguish between a flocculonodular lobe lesion and anterior lobe lesion? (because both similar symptoms)

Back 100

have the pt. lay down and then tell them to move their legs - if difficult: anterior lobe - if normal: flocculonodular.