Motorneuroscience Flashcards
1
Q
Parts of the Brain
A
- Spinal Cord
- Brainstem
- Cerebellum
- Diencephalon
- Cerebral Hemispheres
2
Q
Spinal Cord
A
- Lowest level on the perception/action chain
- Spinal reflexes
- Has afferent and efferent signals
3
Q
Parts of the Brainstem
A
- Medulla
- Pons
- Midbrain
4
Q
Function of the Brainstem
A
- Postural control
- Locomotion
- Lots of facial connections via cranial nerves
- Arousal and awareness
5
Q
Cerebellum Input Reception
A
- Receives input from spinal cord (feedback about movements)
- Receives input from cerebral cortex (planning about movements)
6
Q
Function of Cerebellum
A
Adjust motor responses based on comparison of sensory feedback
7
Q
Parts of the Diencephalon
A
- Thalamus
- Hypothalamus
8
Q
Function of the Thalamus
A
- Receives almost all info going to the cortex
- Acts as a relay station
9
Q
Function of the Hypothalamus
A
Governs the endocrine system
10
Q
Parts of the Cerebral Hemispheres
A
- Cerebral Cortex
- Basal Ganglia
11
Q
Function of Cerebral Cortex
A
Programming movements
12
Q
Areas of the Basal Ganglia
A
- Caudate nucleus
- Putamen
- Globus pallidus
- Substania Nigra
13
Q
Function of Basal Ganglia
A
Plan and execute movement
14
Q
Resting Membrane Potential of a Neuron
A
-70 mV
15
Q
Types of Synaptic Transmission
A
- Summation
- Synaptic Facilitation
- Defacilitation
16
Q
Types of Summation
A
- Spatial Summation
- Temporal Summation
17
Q
Spatial Summation
A
Multiple neurons send PSPs, leading to an action potential
18
Q
Temporal Summation
A
A single neuron repeatedly sends PSPs in rapid succession, leading to an action potential
19
Q
Synaptic Facilitation
A
-
20
Q
Defacilitation
A
-
21
Q
Sensory/Perceptual Systems
A
-
22
Q
Peripheral Receptors
A
- Muscle Spindle
- Golgi Tendon Organ
- Cutaneous Receptors
23
Q
Muscle Spindle Function
A
- Concerned with determining muscle length/stretch
- Acts as a protective measure to prevent injury
- Important for muscle tone
24
Q
Where is the highest concentration of muscle spindles found?
A
In the eyes, neck, and hands
25
Muscle Spindle Composition
- Intrafusal fibers
- Afferent Fibers
- Gamma Motor Neurons
26
Intrafusal Fibers
Nuclear bag
- Clumped (what's clumped?)
Nuclear chain
- Lined up (what's lined up?)
27
Afferent Neurons of the Muscle Spindle
Ia
- Connects to nuclear bag and chain
II
- Connects to nuclear chain
28
Gamma Motor Neurons
Gamma Dynamic
- Connects to nuclear bag
Gamma Static
- Connects to nuclear bag and chain
29
What are alpha motor neurons?
- The efferent nerves that innervate extrafusal muscle fibers (skeletal muscle)
- GMNs intertwine with AMNs
30
Golgi Tendon Organ
- Innervated by Ib afferent neurons
| - No efferent neuron found in the GTO
31
Function of the GTO
-
32
Cutaneous Receptor Function
- Reflexes
- Proprioception
- Sensations
33
Ascending Pathways
- Dorsal Column-Medial Lemniscal System
| - Anterolateral System
34
Sensory Information for the DCML
- Fine touch
- Vibration
- 2-point discrimination
- Proprioception
35
Decussation Point of DCML
Medulla
36
3-Neuron Relay
- 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
37
1st Order Neuron
Includes many collateral branches entering the gray matter
38
2nd Order Neuron
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)
39
3rd Order Neuron
Includes:
- Neurons that connect the thalamus to the sensory cortex
- Neurons that have axons forming part of the thalamocortical radiations
40
Thalamocortical Radiation
Fibers connecting the thalamus to the cerebral cortex
41
Parts of the Dorsal Column
- Fasciculus Gracilis
- Fasciculus Cuneatus
- F. Gracilis + F. Cuneatus = Funiculus
42
Fasciculus Gracilis
- Sensory info for lower body
- Medial
- Senses at T6 and down (still present superior to this)
43
Fasciculus Cuneatus
- Sensory for upper body
- Lateral
- At T5 and up
44
White Matter
- Acts as "stairs" for sensory info (sends info up and down)
- Funiculus = white matter
- Column = white matter
45
Gray Matter
- Acts as a "floor" for sensory info (info moves across)
| - Horn = gray matter
46
Medial Lemniscus
-
47
Function of the Anterolateral System
- Deals with pain
- Minor role in crude touch and pressure
- Thermal?
- Nociception (tissue damage)?
48
Tracts of the Anterolateral System
- Spinothalamic Tract (our focus)
- Spinoreticular Tract
- Spinomesencephalic Tract
49
Spinothalamic Tract
Primary, fast, sharp, localized pain
50
Spinoreticular Tract
- Stops at midbrain
- Arousal response to pain
- Slower than spinothalamic tract
51
Spinomesechephalic Tract
- Stops at midbrain
- Slow, radiating pain
- Slowest tract for pain
52
Somatosensory Cortices
-
53
Association Cortices
-
54
Functions of the Visual System
- Exteroceptive Sense
| - Visual Propriception
55
Exteroceptive Sense
Vision allows us to identify objects in space and determine their movements
56
Visual Proprioception
Allows us to know where our bodies are in space through visual stimuli
57
Types of Photoreceptors
- Rods
| - Cones
58
Rods
- Night vision
| - 20x more rods than cones in retina
59
Cones
- Light and color vision
60
Damage to Rods and Cones
- Rods = night blindness
| - Cones = difficulty seeing with focus directly in front
61
Vertical Cells
-
62
Horizontal Cells
-
63
Central Visual Pathways
-
64
Vestibular System
1 of 3 parts of the Somatosensory Cortex:
- Spindles/GTO
- Cutaneous
- VESTIBULAR
65
Function of Vestibular System
Sensitive to 2 types of information:
- Position of the head in space
- Sudden changes in the direction of movement of the head
66
Peripheral Receptors of Vestibular System
- Semicircular Canals
| - Otolith Organs
67
Semicircular Canals
- 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
Otolith Organs
- Senses head movement in the horizontal and vertical planes
| - Uses crystals attached to hair cells to detect movement
69
Divisions of the Otolith Organs
- Utricle
| - Saccule
70
Utricle
Senses head movement in the horizontal plane
71
Saccule
Senses head movement in the vertical plane
72
Descending Pathways
```
Pyramidal Tracts
- Corticospinal Tracts (lateral and anterior)
- Corticobulbar Tracts
Extrapyramidal Tracts
- Vestibulospinal Tracts
- Rubrospinal Tracts
- Tectospinal Tracts
```
73
Functions of Pyramidal Tracts
Responsible for voluntary control of the musculature
74
Where do corticospinal tracts receive input from?
- Primary motor cortex
- Premotor cortex
- Supplementary motor area
75
Primary Motor Cortex
- Controls absolute force and speed of movement (like a "jock")
- Other areas make action smooth (like a "ballerina")
76
Premotor Cortex
- 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
Supplementary Motor Area
- 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
Corticospinal Tracts
- Lateral Corticospinal Tract
| - Anterior Corticospinal Tract
79
Lateral Corticospinal Tract
- Descends through internal capsule
- Decussation at medulla
- Uses 90% of nerves in the corticospinal tracts
- Influences neck, shoulder, and upper extremity muscles
80
Anterior Corticospinal Tract
Influences trunk and lower limbs
81
Corticobulbar Tract
Controls movement in the face
82
Extrapyramidal Tract Function
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
Extrapyramidal Tracts
- Vestibulospinal Tracts
- Rubrospinal Tracts
- Tectospinal Tracts
84
Vestibulospinal Tracts
Responsible for balance and posture
85
Rubrospinal Tracts
Responsible for upper extremity/hands
86
Tectospinal Tracts
Responsible for head/eye coordination
87
Upper vs Lower Motor Neurons
- All upper motor neurons terminate at the ventral horn of the spinal cord
88
Parts of the Cerebellum
- Flocculonodular Lobe
- Vermis and Intermediate Hemispheres
- Lateral Hemispheres
89
Flocculonodular Lobe
Connects to vestibular system
90
Vermis and Intermediate Hemispheres
- Execution of movement
- Muscle tone (GMNs)
- Feedforward command??
91
Lateral Hemispheres
Planning, preparation, and evaluation of movement
92
Result of a lesion in the cerebellum?
Decomposition of movement (loss of smooth movement)
93
Attachment of the Cerebellum to the Brainstem
- Inferior cerebellar peduncle
- Middle cerebellar peduncle
- Superior cerebellar peduncle
94
Inferior Cerebellar Peduncle
Mainly cerebellar afferents
95
Middle Cerebellar Peduncle
Mainly cerebellar afferents
96
Superior Cerebellar Peduncle
Mainly cerebellar efferents
97
Lobes of the Cerebellar Cortex
- Anterior Lobe
- Posterior Lobe
- Flocculonodular Lobe
98
Anterior Lobe
Concerned with:
- The status of the axial musculature (muscle tone)
- The degree of flexion or extension at any given point in time
99
Flocculonodular Lobe
- Concerned with the status of the head region
| - Control of the eyes and position of the head
100
Posterior Lobe
Concerned with the organization and coordination of motor responses
101
Afferents to the Cerebellum from the Spinal Cord
- 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
Posterior Spinocerebellar Tract
Ipsilateral muscle spindles concerning the status of individual muscles to the cerebellar cortex from the lower limbs and trunk
103
Anterior Spinocerebellar Tract
Ipsilateral signals from the GTO, detecting whole limb movement
104
Cuneocerebellar Tract
Ipsilateral muscle spindles concerning the status of individual muscles to the cerebellar cortex from the upper limb.
105
Afferents to the Cerebellum from the Brainstem
- 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
Layers of the Cerebellar Cortex (superficial to deep)
- Molecular layer
- Purkinje cell layer
- Granule cell layer
107
Afferent Fibers of Cerebellar Cortex
- Climbing fibers
- Mossy fibers
- Excite their target neurons in the cerebellar cortex
- Provide excitatory inputs from collaterals to the deep cerebellar nuclei
108
Climbing Fibers
- 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
Mossy Fibers
- 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
Efferent Fibers of Cerebellar Cortex
- Purkinje cells
| - Deep cerebellar nuclei
111
Deep Cerebellar Nuclei
- 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
Vestibular Nuclei and the Cerebellum
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
Reticular Nuclei and the Cerebellum
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
Interposed Nuclei
- 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
Red Nucleus and the Cerebellum
Rubrospinal Tract
- Inhibits activity of extensors and increases activity of flexors
- Purkinje cell --> interposed nuclei --> red nucleus --> rubrospinal tract
116
Dentate Nucleus
- 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
Cerebral Cortex and the Cerebellum
Corticospinal Tract
- Controls voluntary movements of contralateral limbs and trunk
- Cerebral cortex --> ventrolateral nucleus (in thalamus) --> dentate nucleus
118
Cerebellar Involvement in Nonmotor Tasks
Lateral hemisphere
- Cognition
- Timing
- Motor and nonmotor learning
119
Anatomy of the Basal Ganglia
- Putamen
- Caudate Nucleus
- Globus Pallidus
- Substantia Nigra
120
Role of the Basal Ganglia
Preparation and execution of movement
121
Role of Putamen and Caudate Nucleus (Striatum)
Receive input
122
Role of the Globus Pallidus and Substantia Nigra
Major output areas of the basal ganglia
123
Role of the Subthalamic Nucleus
Indirect pathway
124
Mesencephalon and Brainstem
- Stimulation initiates locomotion and adjusts stepping movements
- Control facilitation and inhibition of muscle tone for posture control
125
Cortical Spinal Pathway of the Basal Ganglia
Controls voluntary movement
126
Brain Stem-Spinal Cord Pathways of the Basal Ganglia
Controls automatic movements
127
Components of the Basal Ganglia
- Neostriatum
- Paleostriatum
- Subthalamic nucleus
- Substantia nigra
128
Neostriatum
- Caudate nucleus
- Putamen
- Primary afferents for inputs from cerebral cortex, thalamus, and substantia nigra
129
Paleostriatum
- Globus pallidus
- Primary output from medial globus pallidus to the thalamus
- Lateral globus pallidus receives input from neostriatum
130
Subthalamic Nucleus
Reciprocal connections with globus pallidus
| - Receives input from lateral globus pallididus and sends output to the medial globus pallidus
131
Substantia Nigra
- Input from neostriatum
| - Outputs to neostriatum, thalamus, and superior colliculus
132
Lentiform nucleus
Globus pallidus + putamen
133
Major Output Pathways of Basal Ganglia
- Ansa lenticularis
| - Lenticular fasciulus
134
Putamen
- Largest afferent source comes from the cerebral cortex
- Putamen receives input source comes from the cerebral cortex
- Putamen is involved with motor functions
135
Caudate Nucleus
- 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
Cortical Input
- 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
Injury to the Substantia Nigra
Diminished substantia nigra is seen in Parkinson's Disease
138
Parts of the Substantia Nigra
- Pars reticulata
| - Pars compacta
139
Role of Dopamine
- The dopamine pathway from the substantia nigra to the neostriatum facilitates movement
- Excites the direct pathway
- Inhibits the indirect pathway
140
Direct Pathway
- 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
Indirect Pathway
- 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
