Motorneuroscience Flashcards

1
Q

Parts of the Brain

A
  • Spinal Cord
  • Brainstem
  • Cerebellum
  • Diencephalon
  • Cerebral Hemispheres
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2
Q

Spinal Cord

A
  • Lowest level on the perception/action chain
  • Spinal reflexes
  • Has afferent and efferent signals
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3
Q

Parts of the Brainstem

A
  • Medulla
  • Pons
  • Midbrain
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4
Q

Function of the Brainstem

A
  • Postural control
  • Locomotion
  • Lots of facial connections via cranial nerves
  • Arousal and awareness
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5
Q

Cerebellum Input Reception

A
  • Receives input from spinal cord (feedback about movements)

- Receives input from cerebral cortex (planning about movements)

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6
Q

Function of Cerebellum

A

Adjust motor responses based on comparison of sensory feedback

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7
Q

Parts of the Diencephalon

A
  • Thalamus

- Hypothalamus

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8
Q

Function of the Thalamus

A
  • Receives almost all info going to the cortex

- Acts as a relay station

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9
Q

Function of the Hypothalamus

A

Governs the endocrine system

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10
Q

Parts of the Cerebral Hemispheres

A
  • Cerebral Cortex

- Basal Ganglia

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11
Q

Function of Cerebral Cortex

A

Programming movements

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12
Q

Areas of the Basal Ganglia

A
  • Caudate nucleus
  • Putamen
  • Globus pallidus
  • Substania Nigra
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13
Q

Function of Basal Ganglia

A

Plan and execute movement

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14
Q

Resting Membrane Potential of a Neuron

A

-70 mV

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15
Q

Types of Synaptic Transmission

A
  • Summation
  • Synaptic Facilitation
  • Defacilitation
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16
Q

Types of Summation

A
  • Spatial Summation

- Temporal Summation

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17
Q

Spatial Summation

A

Multiple neurons send PSPs, leading to an action potential

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18
Q

Temporal Summation

A

A single neuron repeatedly sends PSPs in rapid succession, leading to an action potential

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19
Q

Synaptic Facilitation

A

-

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20
Q

Defacilitation

A

-

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21
Q

Sensory/Perceptual Systems

A

-

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22
Q

Peripheral Receptors

A
  • Muscle Spindle
  • Golgi Tendon Organ
  • Cutaneous Receptors
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23
Q

Muscle Spindle Function

A
  • Concerned with determining muscle length/stretch
  • Acts as a protective measure to prevent injury
  • Important for muscle tone
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24
Q

Where is the highest concentration of muscle spindles found?

A

In the eyes, neck, and hands

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25
Q

Muscle Spindle Composition

A
  • Intrafusal fibers
  • Afferent Fibers
  • Gamma Motor Neurons
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26
Q

Intrafusal Fibers

A

Nuclear bag
- Clumped (what’s clumped?)
Nuclear chain
- Lined up (what’s lined up?)

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27
Q

Afferent Neurons of the Muscle Spindle

A

Ia
- Connects to nuclear bag and chain
II
- Connects to nuclear chain

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28
Q

Gamma Motor Neurons

A

Gamma Dynamic
- Connects to nuclear bag
Gamma Static
- Connects to nuclear bag and chain

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29
Q

What are alpha motor neurons?

A
  • The efferent nerves that innervate extrafusal muscle fibers (skeletal muscle)
  • GMNs intertwine with AMNs
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30
Q

Golgi Tendon Organ

A
  • Innervated by Ib afferent neurons

- No efferent neuron found in the GTO

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31
Q

Function of the GTO

A

-

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32
Q

Cutaneous Receptor Function

A
  • Reflexes
  • Proprioception
  • Sensations
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33
Q

Ascending Pathways

A
  • Dorsal Column-Medial Lemniscal System

- Anterolateral System

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34
Q

Sensory Information for the DCML

A
  • Fine touch
  • Vibration
  • 2-point discrimination
  • Proprioception
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35
Q

Decussation Point of DCML

A

Medulla

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36
Q

3-Neuron Relay

A
  • 1st order neuron (primary) conveys info from the receptors to the medulla
  • 2nd order neuron (secondary) conveys info from the medulla to the thalamus
  • 3rd order neuron (tertiary) conveys info from the thalamus to the cerebral cortex
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37
Q

1st Order Neuron

A

Includes many collateral branches entering the gray matter

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38
Q

2nd Order Neuron

A

Includes:

  • Cell bodies located in the nucleus gracilis or cuneatus
  • Axons that cross the midline as the internal arcuate fibers (which then ascend to the thalamus)
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39
Q

3rd Order Neuron

A

Includes:

  • Neurons that connect the thalamus to the sensory cortex
  • Neurons that have axons forming part of the thalamocortical radiations
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40
Q

Thalamocortical Radiation

A

Fibers connecting the thalamus to the cerebral cortex

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41
Q

Parts of the Dorsal Column

A
  • Fasciculus Gracilis
  • Fasciculus Cuneatus
  • F. Gracilis + F. Cuneatus = Funiculus
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42
Q

Fasciculus Gracilis

A
  • Sensory info for lower body
  • Medial
  • Senses at T6 and down (still present superior to this)
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43
Q

Fasciculus Cuneatus

A
  • Sensory for upper body
  • Lateral
  • At T5 and up
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44
Q

White Matter

A
  • Acts as “stairs” for sensory info (sends info up and down)
  • Funiculus = white matter
  • Column = white matter
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45
Q

Gray Matter

A
  • Acts as a “floor” for sensory info (info moves across)

- Horn = gray matter

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46
Q

Medial Lemniscus

A

-

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47
Q

Function of the Anterolateral System

A
  • Deals with pain
  • Minor role in crude touch and pressure
  • Thermal?
  • Nociception (tissue damage)?
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48
Q

Tracts of the Anterolateral System

A
  • Spinothalamic Tract (our focus)
  • Spinoreticular Tract
  • Spinomesencephalic Tract
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49
Q

Spinothalamic Tract

A

Primary, fast, sharp, localized pain

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50
Q

Spinoreticular Tract

A
  • Stops at midbrain
  • Arousal response to pain
  • Slower than spinothalamic tract
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51
Q

Spinomesechephalic Tract

A
  • Stops at midbrain
  • Slow, radiating pain
  • Slowest tract for pain
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52
Q

Somatosensory Cortices

A

-

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53
Q

Association Cortices

A

-

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54
Q

Functions of the Visual System

A
  • Exteroceptive Sense

- Visual Propriception

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55
Q

Exteroceptive Sense

A

Vision allows us to identify objects in space and determine their movements

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56
Q

Visual Proprioception

A

Allows us to know where our bodies are in space through visual stimuli

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57
Q

Types of Photoreceptors

A
  • Rods

- Cones

58
Q

Rods

A
  • Night vision

- 20x more rods than cones in retina

59
Q

Cones

A
  • Light and color vision
60
Q

Damage to Rods and Cones

A
  • Rods = night blindness

- Cones = difficulty seeing with focus directly in front

61
Q

Vertical Cells

A

-

62
Q

Horizontal Cells

A

-

63
Q

Central Visual Pathways

A

-

64
Q

Vestibular System

A

1 of 3 parts of the Somatosensory Cortex:

  • Spindles/GTO
  • Cutaneous
  • VESTIBULAR
65
Q

Function of Vestibular System

A

Sensitive to 2 types of information:

  • Position of the head in space
  • Sudden changes in the direction of movement of the head
66
Q

Peripheral Receptors of Vestibular System

A
  • Semicircular Canals

- Otolith Organs

67
Q

Semicircular Canals

A
  • Senses angular acceleration of the head
  • Has a membranous labyrinth filled with endolymph
  • Hair cells are found in the ampulla
  • When the head rotates, the endolymph moves the hair cells, leading to an action potential
68
Q

Otolith Organs

A
  • Senses head movement in the horizontal and vertical planes

- Uses crystals attached to hair cells to detect movement

69
Q

Divisions of the Otolith Organs

A
  • Utricle

- Saccule

70
Q

Utricle

A

Senses head movement in the horizontal plane

71
Q

Saccule

A

Senses head movement in the vertical plane

72
Q

Descending Pathways

A
Pyramidal Tracts
- Corticospinal Tracts (lateral and anterior)
- Corticobulbar Tracts
Extrapyramidal Tracts
- Vestibulospinal Tracts
- Rubrospinal Tracts
- Tectospinal Tracts
73
Q

Functions of Pyramidal Tracts

A

Responsible for voluntary control of the musculature

74
Q

Where do corticospinal tracts receive input from?

A
  • Primary motor cortex
  • Premotor cortex
  • Supplementary motor area
75
Q

Primary Motor Cortex

A
  • Controls absolute force and speed of movement (like a “jock”)
  • Other areas make action smooth (like a “ballerina”)
76
Q

Premotor Cortex

A
  • Activation when the presentation of a stimulus normally elicits a response
  • Vision plays a large role
  • EX: a sudden red light, brake lights, etc
77
Q

Supplementary Motor Area

A
  • Activated when movements are planned (internal)
  • Becomes less activated as we learn the sequence
  • Has to work harder when movement is more complex
  • Fires even when mentally rehearsing the action
78
Q

Corticospinal Tracts

A
  • Lateral Corticospinal Tract

- Anterior Corticospinal Tract

79
Q

Lateral Corticospinal Tract

A
  • Descends through internal capsule
  • Decussation at medulla
  • Uses 90% of nerves in the corticospinal tracts
  • Influences neck, shoulder, and upper extremity muscles
80
Q

Anterior Corticospinal Tract

A

Influences trunk and lower limbs

81
Q

Corticobulbar Tract

A

Controls movement in the face

82
Q

Extrapyramidal Tract Function

A

Responsible for the involuntary and automatic control of all musculature
- Muscle tone
- Balance
- Posture
- Locomotion
Originates in the brainstem, goes to the spinal cord

83
Q

Extrapyramidal Tracts

A
  • Vestibulospinal Tracts
  • Rubrospinal Tracts
  • Tectospinal Tracts
84
Q

Vestibulospinal Tracts

A

Responsible for balance and posture

85
Q

Rubrospinal Tracts

A

Responsible for upper extremity/hands

86
Q

Tectospinal Tracts

A

Responsible for head/eye coordination

87
Q

Upper vs Lower Motor Neurons

A
  • All upper motor neurons terminate at the ventral horn of the spinal cord
88
Q

Parts of the Cerebellum

A
  • Flocculonodular Lobe
  • Vermis and Intermediate Hemispheres
  • Lateral Hemispheres
89
Q

Flocculonodular Lobe

A

Connects to vestibular system

90
Q

Vermis and Intermediate Hemispheres

A
  • Execution of movement
  • Muscle tone (GMNs)
  • Feedforward command??
91
Q

Lateral Hemispheres

A

Planning, preparation, and evaluation of movement

92
Q

Result of a lesion in the cerebellum?

A

Decomposition of movement (loss of smooth movement)

93
Q

Attachment of the Cerebellum to the Brainstem

A
  • Inferior cerebellar peduncle
  • Middle cerebellar peduncle
  • Superior cerebellar peduncle
94
Q

Inferior Cerebellar Peduncle

A

Mainly cerebellar afferents

95
Q

Middle Cerebellar Peduncle

A

Mainly cerebellar afferents

96
Q

Superior Cerebellar Peduncle

A

Mainly cerebellar efferents

97
Q

Lobes of the Cerebellar Cortex

A
  • Anterior Lobe
  • Posterior Lobe
  • Flocculonodular Lobe
98
Q

Anterior Lobe

A

Concerned with:

  • The status of the axial musculature (muscle tone)
  • The degree of flexion or extension at any given point in time
99
Q

Flocculonodular Lobe

A
  • Concerned with the status of the head region

- Control of the eyes and position of the head

100
Q

Posterior Lobe

A

Concerned with the organization and coordination of motor responses

101
Q

Afferents to the Cerebellum from the Spinal Cord

A
  • Info on the status and position of individual and groups of muscle is sent to the anterior lobe to control muscle tone and execution of movements
  • Posterior (Dorsal) spinocerebellar tract
  • Anterior (Ventral) spinocerebellar tract
  • Cuneocerebellar tract
102
Q

Posterior Spinocerebellar Tract

A

Ipsilateral muscle spindles concerning the status of individual muscles to the cerebellar cortex from the lower limbs and trunk

103
Q

Anterior Spinocerebellar Tract

A

Ipsilateral signals from the GTO, detecting whole limb movement

104
Q

Cuneocerebellar Tract

A

Ipsilateral muscle spindles concerning the status of individual muscles to the cerebellar cortex from the upper limb.

105
Q

Afferents to the Cerebellum from the Brainstem

A
  • Info on both the coordination of movements and movements that govern equilibrium and maintenance of an erect posture
  • Olivocerebellar tract
  • Vestibulocerebellar fibers
  • Reticulocerebellar fibers
106
Q

Layers of the Cerebellar Cortex (superficial to deep)

A
  • Molecular layer
  • Purkinje cell layer
  • Granule cell layer
107
Q

Afferent Fibers of Cerebellar Cortex

A
  • Climbing fibers
  • Mossy fibers
  • Excite their target neurons in the cerebellar cortex
  • Provide excitatory inputs from collaterals to the deep cerebellar nuclei
108
Q

Climbing Fibers

A
  • Go all the way to the top
  • Arise from the inferior olivary nucleus and ascend through the granular and Purkinje cell layers to reach the molecular layer
  • 1 climbing fiber excites a single muscle cell.
109
Q

Mossy Fibers

A
  • Distributed widely throughout the cerebellum
  • As they go through the granular layer they branch and terminate by forming rosesettes held by claw-like dendrites of the granule cells
  • A single mossy fiber can captivate many granule cells
110
Q

Efferent Fibers of Cerebellar Cortex

A
  • Purkinje cells

- Deep cerebellar nuclei

111
Q

Deep Cerebellar Nuclei

A
  • Cerebellar cortex signals to the deep cerebellar nuclei via the Purkinje cell axon
  • Creates the initial signal that the deep cerebellar nucleus receives from the mossy or climbing fiber
  • Fastigial nucleus
  • Globose nucleus
  • Emboliform nucleus
  • Dentate nucleus
112
Q

Vestibular Nuclei and the Cerebellum

A

Vestibulospinal Tract

  • Controls the muscles for posture and balance
  • Adjusts position of the head in response to changes in posture
  • Fastigial nucleus –> vestibular nuclei –> vestibulospinal tract
113
Q

Reticular Nuclei and the Cerebellum

A

Medullary (lateral) Reticulospinal Tract
- Powerfully suppresses extensor spinal activity and reduces muscle tone
- Fastigial nucleus –> medullary reticular formation –> reticulospinal tract
Pontine (medial) Reticulospinal Tract
- Facilitates extensor spinal activity and increases muscle tone
- Fastigial nucleus –> pontine reticular formation –> reticulospinal tract

114
Q

Interposed Nuclei

A
  • Purkinje cell outputs from the intermediate zone of the cerebellar hemisphere go to the interposed nuclei
  • Interposed nuclei project through the superior cerebellar peduncle to the red nucleus
  • Feedback circuit that controls coordination and execution of movements associated mainly with muscles of the arm
115
Q

Red Nucleus and the Cerebellum

A

Rubrospinal Tract

  • Inhibits activity of extensors and increases activity of flexors
  • Purkinje cell –> interposed nuclei –> red nucleus –> rubrospinal tract
116
Q

Dentate Nucleus

A
  • Purkinje cell outputs from lateral regions of the cerebellar hemisphere go to the dentate nucleus
  • The dentate nucleus projects through the superior cerebellar peduncle to the thalamus
  • Feedback signals from the cerebellar cortex assist in the planning, coordination, and execution of motor responses initiated from the cerebral cortex
117
Q

Cerebral Cortex and the Cerebellum

A

Corticospinal Tract

  • Controls voluntary movements of contralateral limbs and trunk
  • Cerebral cortex –> ventrolateral nucleus (in thalamus) –> dentate nucleus
118
Q

Cerebellar Involvement in Nonmotor Tasks

A

Lateral hemisphere

  • Cognition
  • Timing
  • Motor and nonmotor learning
119
Q

Anatomy of the Basal Ganglia

A
  • Putamen
  • Caudate Nucleus
  • Globus Pallidus
  • Substantia Nigra
120
Q

Role of the Basal Ganglia

A

Preparation and execution of movement

121
Q

Role of Putamen and Caudate Nucleus (Striatum)

A

Receive input

122
Q

Role of the Globus Pallidus and Substantia Nigra

A

Major output areas of the basal ganglia

123
Q

Role of the Subthalamic Nucleus

A

Indirect pathway

124
Q

Mesencephalon and Brainstem

A
  • Stimulation initiates locomotion and adjusts stepping movements
  • Control facilitation and inhibition of muscle tone for posture control
125
Q

Cortical Spinal Pathway of the Basal Ganglia

A

Controls voluntary movement

126
Q

Brain Stem-Spinal Cord Pathways of the Basal Ganglia

A

Controls automatic movements

127
Q

Components of the Basal Ganglia

A
  • Neostriatum
  • Paleostriatum
  • Subthalamic nucleus
  • Substantia nigra
128
Q

Neostriatum

A
  • Caudate nucleus
  • Putamen
  • Primary afferents for inputs from cerebral cortex, thalamus, and substantia nigra
129
Q

Paleostriatum

A
  • Globus pallidus
  • Primary output from medial globus pallidus to the thalamus
  • Lateral globus pallidus receives input from neostriatum
130
Q

Subthalamic Nucleus

A

Reciprocal connections with globus pallidus

- Receives input from lateral globus pallididus and sends output to the medial globus pallidus

131
Q

Substantia Nigra

A
  • Input from neostriatum

- Outputs to neostriatum, thalamus, and superior colliculus

132
Q

Lentiform nucleus

A

Globus pallidus + putamen

133
Q

Major Output Pathways of Basal Ganglia

A
  • Ansa lenticularis

- Lenticular fasciulus

134
Q

Putamen

A
  • Largest afferent source comes from the cerebral cortex
  • Putamen receives input source comes from the cerebral cortex
  • Putamen is involved with motor functions
135
Q

Caudate Nucleus

A
  • Receives inputs from cortical association regions, frontal eye fields, and limbic regions of cortex
  • Involved with cognitive and emotional aspects of movement and eye movements
136
Q

Cortical Input

A
  • Putamen receives fibers from motor regions of the cerebral cortex
  • Caudate nucleus receives fibers from association regions (temporal and parietal lobes) and frontal and prefrontal lobes
137
Q

Injury to the Substantia Nigra

A

Diminished substantia nigra is seen in Parkinson’s Disease

138
Q

Parts of the Substantia Nigra

A
  • Pars reticulata

- Pars compacta

139
Q

Role of Dopamine

A
  • The dopamine pathway from the substantia nigra to the neostriatum facilitates movement
  • Excites the direct pathway
  • Inhibits the indirect pathway
140
Q

Direct Pathway

A
  • The net effect is excitation of the motor regions of cortex
  • Cortex excites (glutamate) the neostriatum, which inhibits (GABA) the internal globus pallidus, which inhibits (GABA) the thalamus which excites the motor regions of the cortex
141
Q

Indirect Pathway

A
  • The net effect is inhibition of the motor regions of the cortex
  • Cortex excites (glutamate) the neostriatum, which inhibits (GABA) the external globus pallidus, which inhibits (GABA) the subthalamic nucleus, which excites (glutamate) the internal globus pallidus, which inhibits (GABA) the thalamus, which inhibits motor regions of the cortex