Contributions of Cerebellum and Basal Nuclei to Motor Function Flashcards
0
Q
Describe the Primary motor cortex
A
Signals motor neurons to contract skeletal muscle fibers
Signals via the corticospinal (pyramidal) tract
Execution of commands is preceded by extensive processing by cerebellum and basal nuclei
1
Q
What are the motor control centers of the cerebral cortex?
A
Primary motor cortex (Area 4)
Premotor cortex (Area 6)
Supplementary motor area (Area 6)
2
Q
Describe the premotor cortex
A
Plans movements based on sensory and visual cues
3
Q
Describe supplementary motor area
A
Retrieves and coordinates memorized motor sequences
4
Q
What are the functions of the motor cortex system?
A
- provides most of activating signals to spinal cord
- issues sequential and parallel commands that initiate various cord patterns
- cortical patterns are usually complex and can be learned
- cord patterns are mainly determined by heredity and are “hard wired”
5
Q
What does the cerebellum play major roles in?
A
The timing of motor activities and in rapid, smooth progression from one muscle movement to the next
6
Q
What is not essential for locomotion,
helps sequence motor activities,
monitors and makes corrective adjustments to motor activities while they are being executed,
compares actual movements with intended movements,
aids cortex in planning next sequential movement,
and learns by its mistakes?
A
Cerebellum
7
Q
What functions with spinal cord to enhance the stretch reflex
functions with brain stem to make postural movements
and functions with cerebral cortex to provide accessory motor functions?
A
Cerebellum
8
Q
What turns on antagonist at appropriate time
Helps program muscle contraction in advance
and functions mainly when muscle movements have to be rapid?
A
Cerebellum
9
Q
What helps to plan and control complex patterns of muscle movement, controlling relative intensities of the separate movements, directions of movements and sequencing of multiple successive and parallel movements?
A
Basal nuclei
10
Q
What plans and executes motor commands in concert with cerebral cortex; and helps cortex execute subconscious but learned pattern?
A
Basal nuclei
11
Q
What helps plan multiple parallel sequential patterns?
A
basal nuclei
12
Q
What controls complex patterns of motor activity?
A
Basal nuclei
13
Q
What does not cause any conscious sensation and rarely causes any motor movement?
A
Electrical excitation of the cerebellum
14
Q
Removal of what causes body movements to become highly abnormal?
A
Removal of the cerebellum
15
Q
The two hemispheres of the cerebellum are separated by:
A
vermis
16
Q
What is each hemisphere of the cerebellum divided into?
A
An intermediate zone and a lateral zone
17
Q
The cerebellum is anatomically divided into how many lobes?
A
3
18
Q
What are the three lobes of the cerebellum?
A
Anterior, posterior, and flocculonodular lobe
19
Q
What lobe of the cerebellum is associated with vestibular system?
A
Flocculonodular lobe
20
Q
What is the location for control functions for muscle movements of the axial body, neck, shoulder, and hips?
A
Vermis
21
Q
What is concerned with controlling muscle contractions in the distal portions of the upper and lower limbs, esp. hands, feet, fingers, and toes?
A
Intermediate zone
22
Q
What is associated with cerebral cortex with planning of sequential motor movements?
A
Lateral zone
23
Q
The cortex of the grey matter of cerebellum consists of what?
A
transversely arranged narrow gyri called folia
24
Each cortex of the grey matter of cerebellum has what intracerebellar nuclei?
Dentate
Emboliform
Globose
Fastigial
25
Lesions in which nuclei will cause extremity ataxia?
Dentate, emboliform and globose nuclei
26
Fibers of which intracerebellar nuclei project to the red nucleus?
Dentate, emboliform and globose
27
Which intracerebellar nuclei are related to limb musculature and fine manipulative movement?
Dentat, emboliform and globose
28
Lesion in what intracerebellar nuclei will lead to trunk ataxia?
Fastigial nuclei
29
Fibers of what intracerebellar nuclei project to reticular formation and vestibular nuclei?
Fastigial nuclei
30
What intracerebellar nuclei are related to postural activity and limb movements via reticulospinal and vestibulospinal tracts?
Fastigial nuclei
31
What are the cells in cerebellar cortex?
Granular, golgi, basket, and stellate cells
32
Which cells in the cerebellar cortex project from parallel fibers to granular cell bodies (-)?
Golgi cells
33
Which cells in the cerebellar cortex have axons that form parallel fibers in the cortex (+)?
Granular cells
34
Which cells in the cerebellar cortex project from parallel fibers to purkinje axon hillock (-)?
Basket cells
35
Which cells in the cerebellar cortex project from parallel fibers to purkinje dendrites (-)?
Stellate cells
36
Which cells in the cerebellar cortex provides lateral inhibition on adjacent purkinje cells to provide damping?
Basket cells and stellate cells
37
Which cells in the cerebellar cortex have extensive dendritic branching, receive input from parallel fibers (20k synapses), project to intracerebellar nuclei (-), and are the ONLY output from cortex?
Purkinje cells
38
Which cells in the cerebellar cortex are the ONLY output from cortex?
Purkinje cells
39
How many functional units are in the cerebellar cortex?
30 million
40
What is each functional unit of cerebellar cortex centered on?
A purkinje cell and a corresponding deep nuclear cell
41
Output from a functional unit is from what?
A deep nuclear cell
42
Afferent inputs to the cerebellum are mainly from what?
The climbing fibers and the mossy fibers
43
Where do all climbing fibers originate from?
The inferior olives
44
Mossy fibers enter cerebellum from a variety of sources and send excitatory collaterals to ___ ___ ___ and then synapse in ____ layers with thousands of _____ _____.
Deep nuclear cells
Granular
Granule cells
45
Granule cells send axons to _____ _____ ______
Outer cerebellar surface
46
Granule cell axons branch in ____ directions parallel to folia
Two
47
Dendrites of purkinje cells project to what?
Parallel fibers of the granule cell axons
48
direct stimulation by ______ and ______ fibers excite deep nuclear cells.
Climbing and mossy fibers
49
Purkinje cell signals inhibit what?
Deep nuclear cells
50
Basket cells and stellate cells also function as _______ cells
Inhibitory
51
The nervous system uses the cerebellum to coordinate motor control functions at what three levels?
Vestibulocerebellum (vestibular system, cerebellum)
Spinocerebellum (Spinal cord , cerebellum)
Cerebrocerebellum (cerebellum, cerebral cortex)
52
The vestibulocerebellum consists of what?
Flocculonodular lobes and vermis, and vestibular system
53
The vestibulocerebellum receives fibers from what?
```
Vestibular system
Oculomotor system (pontocerebellar fibers)
```
54
What does the vestibulocerebellum send output primarily to?
Vestibular system
55
The loss of flocculonodular lobes, which are a part of the vestibulocerebellum, would cause what?
Extreme disturbance of equilibrium and postural movements
56
Most body movements are _______
Pendular (swing back and forth)
57
All pendular movements have a tendency to _______.
overshoot
58
Appropriate learned subconscious signals from intact ______ can stop movement precisely at intended point. (=damping system)
Cerebellum
59
What changes occur when cerebellum is removed?
Movements are slow to develop
Force developed is weak
Movements are slow to turn off bc of momentum
60
What does the spinocerebellum consists of?
Mostly of vermis and intermediate zone
61
The spinocerebellum receives information from ____ ____ and ___ ____ telling cerebellum intended sequential plan of movement for the next few fractions of a second.
Motor cortex
| red nucleus
62
Spinocerebellum feedback information comes from _______, telling cerebellum what actual movements resulted
periphery
63
The spinocerebellum compares two sources of information and sends corrections to what?
Motor cortex via thalamus
| and magnocellular portions of red nucleus
64
What does the cerebrocerebellum consists of?
Lateral parts of hemispheres
65
What is the cerebrocerebellum mostly associated with?
The premotor, primary and association somatosensory areas of the cerebral cortex
66
What does the cerebrocerebellum receive?
Corticopontocerebellar projections
67
What is the cerebrocerebellum involved in?
Coordination of skilled movement and speech
68
Cerebrocerebellum plans as much as _____ of a second in advance of actual movements. This is referred to as "_____ _____".
Tenths
| "motor imagery"
69
define the following clinical abnormalities of the cerebrocerebellum:
Dysmetria
Ataxia
Dysmetria: refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia.
Ataxia: is a neurological sign consisting of lack of voluntary coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum.
70
Describe the afferent tract of corticopontocerebellar
Cortex (cerebral) -> pontine-> cerebellum
| Motor and premotor cortices/somatosensory cortex -> pontine nuclei -> lateral divisions of cerebellum
71
Describe the afferent tract of vestibulocerebellar
Vestibular system->cerebellum
Terminates in flocculonodular lobes
Oldest part of cerebellum. Balance and equilibrium
72
Describe the afferent tract of reticulocerebellar
Reticular system -> cerebellum
| Terminates primarily in the vermis
73
Describe the afferent tract of spinocerebellar
Spinal cord -> cerebellum
Dorsal and ventral pathway
Transmit signals at 120 m/sec (fast)
74
The corticopontocerebellar, vestibulocerebellar, reticulocerebellar, and spinocerebellar tracts all form what?
Mossy fibers that terminate on the granule cells in the cerebellar cortex (+)
75
Describe the afferent tract of dorsal spinocerebellar
Muscle spindles->ipsilaterally in vermis and intermediate zones
76
The dorsal spinocerebellar apprise cerebellum of momentary status of what?
Muscle contractions
Degree of tension on muscle spindles
Position and rates of movement of parts of the body
Forces acting on surfaces of the body
77
The ventral spinocerebellar terminates how?
Ipsilaterally and contralaterally
78
The ventral spinocerebellar tracts are excited by signals coming from what?
Cortex via corticospinal and rubrospinal tracts
| Internal motor pattern generators within spinal cord
79
The ventral spinocerebellar tells the cerebellum what?
Which motor signals have arrives at the anterior horns
| This feedback = efference copy of the anterior horn motor drive
80
Describe the olivocerebellar afferent tract
Nurons project from inferior olivary nuclei (in medulla) to Purkinje cell dendrites (+) and to intracerebellar nuceli
81
Axons of olivocerebellar form what?
Climbing fibers
82
What do climbing fibers do to purkinje cells?
Clinbing fiber causes a single, prolonged (up to one second) action potential on each purkinje cell with which it connects.
83
How many climbing fibers per pukinje cells?
ONE climbing fiber per 5-10 Purkinje cells
84
What does each signal from climbing fiber start out as?
A strong spike and is followed by a series of weak secondary spikes (=complex spike)
85
Mossy fibers send signals to what?
(+) signals to granule cells
86
Efferent tracts come from _______ and afferent tracts go to ________.
Cerebellum
| Cerebellum
87
Describe the cerebelloreticular efferent tract
Fastigial nuclei -> reticular nuceli in pons and medulla
88
Describe the cerebellothalamocortical efferent tract
Dentate, emboliform, globose nuceli -> thalamus -> motor cortex
89
Describe the cerebellorubral efferent tract
Dentate, emboliform, globose nuclei -> red nucleus
90
Describe the cerebellovestibular efferent tract
Cerebellum -> vestibular nuceli
91
define the following clinical abnormalities of the cerebrocerebellum:
Past pointing
Dysdiadochokinesia
Dysarthria
Past pointing is a sign of limb ataxia. Suggest an ipsilateral cerebellar lesion
Dysdiadochokinesia: medical term for an impaired ability to perform rapid, alternating movements
Dysarthria: a motor speech disorder. It results from impaired movement of the muscles used for speech production, including the lips, tongue, vocal folds, and/or diaphragm.
92
# define the following clinical abnormalities of the cerebrocerebellum:
Cerebellar nystagmus
| Hypotonia
Cerebellar nystagmus: a condition of involuntary eye movement, acquired in infancy or later in life, that may result in reduced or limited vision
Hypotonia: a state of low muscle tone[1] (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength.
93
What are ballistic movements
Ballistic movement can be defined as muscle contractions that exhibit maximum velocities and accelerations over a very short period of time. They exhibit high firing rates, high force production, and very brief contraction times. Examples of ballistic muscle movements can be observed in nature and are involved in many aspects of an animals’ biology including prey capture, defense mechanisms, and locomotion along with many others.
94
The basal nuclei receive most of their input from what?
The cerebral cortex
95
The basal nuclei return most of their output to what?
To the cerebral cortex
96
What is the principal role of the basal nuclei?
To work with corticospinal system to control complex patterns of motor activity
97
The basal nuclei consists of paired:
```
Caudate nucleus
Putamen
Globus pallidus
Substantia nigra
Subthalamic nucleus
```
98
What are the two major basal nuclei circuits?
Putamen circuit
| Caudate nucleus circuit
99
What is the function of the putamen circuit?
Subconscious execution of learned patterns of movement
100
What is the putamen circuit pathway?
```
Cerebral cortex (any part-premotor, supplementary motor, and/or somatosensory) ->
Putamen-> Globus pallidus (internal) -> Thalamic relay nuclei (ventroanterior and ventrolateral nuclei) ->
Primary motor cortex (and premotor/supplementary)
```
***Not that it bypasses caudate nucleus
101
Lesions in what part of the basal nuclei will result in continuous spontaneous writhing movements of a hand, arm, neck or face = athetosis?
Globus pallidus
102
Lesions in what part of the basal nuclei will result in sudden, flailing movements of an entire limb = hemiballismus?
Subthalamus
103
Lesions in what part of the basal nuclei will result in flicking movements in hands, face, or elsewhere = chorea?
Putamen
104
Lesions in what part of the basal nuclei will result in rigidity, akinesia, and tremors = Parkinson's disease
Substantia nigra
105
What is the function of the caudate circuit?
For cognitive planning of sequential and parallel motor patterns
Plays a major role in cognitive control of motor activity
106
What is the caudate circuit pathway?
Cerebral cortex (premotor, supplementary motor, somatosensory) ->
Caudate nucleus ->
Globus pallidus (internal) ->
Thalamic relay nuclei (ventroanterior and ventrolateral nuclei) ->
Premotor and supplementary motor cortex
107
Substantia nigra -> caudate nucleus and putamen uses what neurotransmitters?
Dopamine (inhibitory)
108
Caudate nucleus and putamen -> globus pallidus and substantia nigra uses what neurotransmitters?
GABA (inhibitory)
109
Cortex -> caudate nucleus and putamen uses what neurotransmitters?
Acetylcholine
110
Multiple pathways from brain stem uses what neurotransmitters?
Norepinephrine, serotonin (inhibitory), encephalin
111
Multiple glutamate pathways provide what?
Provide most of the excitatory signals
112
What is Parkinson's also known as?
Paralysis agitans
113
What does Parkinsons' result from?
From widespread destruction of pars compacta of substantia nigra that sends dopaminergic fibers to caudate nucleus and putamen
114
The follow characteristics are of what disease?
Rigidity of much body musculature
Involuntary tremors of involved areas even at rest at a fixed rate
Serious difficulty in initiating movement (akinesia)
Postural instability
Dysphagia, speech disorders, gait disturbances, fatigue
Parkinson's
115
What disease usually becomes symptomatic around 30-40 years of age
Characteristics:
Flicking movements of individual muscles
Progressive severe distortional movements of entire body
Severe dementia
Motor dysfunctions
Huntington's disease
116
Abnormal movements with huntington's disease is probably caused by what?
Loss of most of cell bodies of GABA-secreting neurons of caudate nucleus and putamen and of Ach neurons in other parts of the brain
117
GABA neurons normally inhibit parts of what?
The globus pallidus and substantia nigra
