Higher Centers of Motor Control - Descending Pathways (11) EXAM 3 Material Flashcards
1
Q
Primary Motor Cortex, aka:
A
Precentral Gyrus
2
Q
Which part of the frontal lobe controls contralateral voluntary movements?
A
Primary Motor Cortex (precentral gyrus)
3
Q
Controls fine movements of hands and face (hand, foot and lower face are entirely contralateral)
A
Primary Motor cortex (precentral gyrus)
4
Q
What part of the frontal lobe controls motor planning and trunk and girdle muscles of the body?
A
Premotor cortex
5
Q
What part of the frontal lobe controls motor planning, initiation of movement, orientation of eyes and head, and planning bimanual and sequential movements?
A
Supplementary Motor Cortex
6
Q
What two arts of the frontal lobe are important in motor planning?
A
Premotor cortex and supplementary motor cortex
7
Q
Where do the motor cortices receive info from?
A
Secondary association areas, somatosensory areas, basal ganglia and cerebellum
8
Q
What type of organization is the primary motor cortex (precentral gyrus)
A
Somatotopic (motor homunculus)
9
Q
What does the homunculus of the primary motor cortex have the greatest representation of?
A
Hand and lower face (NOT rigidly fixed)
10
Q
Where does the primary motor cortex (precentral gyrus) receive info from?
A
Thalamus
11
Q
Dorsolateral Tracts: control
A
Limb flexion and fine movement (buttoning a button)
12
Q
Dorsolateral Tracts:
A
- Lateral corticospinal tract
- Rubrospinal tract
- Corticobulbar Tract
13
Q
Which tracts control limb flexion and fine movements?
A
Dorsolateral tracts
14
Q
Which tracts control trunk and limb muscles?
A
Ventromedial System
15
Q
Ventromedial System Tracts:
A
- Ventral/Anterior corticospinal tract
- Medial vestibulospinal tract
- Lateral vestibulospinal tract
16
Q
Lateral corticospinal tract: What system?
A
Dorsolateral system
17
Q
Lateral corticospinal tract: Function:
A
Voluntary control of distal muscles needed for precise movement
(Fractionation)
18
Q
Fractionation Definition (part of which tract and what group)
A
Ability to activate individual muscles independently of other muscles
ex: Mr Burns in simpsons - evil villain / buttoning button
Lateral Corticospinal tract
Dorsolateral System
19
Q
Pathway of Lateral corticospinal tract:
A
- Originates in primary motor, premotor and supplementary motor cortex
- Decussation at pyramids of medulla
- Travels through the lateral funiculus (white matter (in the SC
- Most fibers terminate by contacting interneurons in the spinal cord; some synapse directly with LMNs
20
Q
Lateral corticospinal tract: How many neurons?
A
ONE long neuron, NOT a chain
21
Q
Ventral/Anterior Corticospinal Tract: What system?
A
Ventromedial system
22
Q
Ventral/Anterior corticospinal tract: function
A
Control of neck, shoulder and trunk muscles
23
Q
Ventral/Anterior corticospinal tract pathway:
A
- Descends ipsilaterally
- Travels through anterior funiculus of the SC
- Can have a bilateral projection at the level of the SC
24
Q
Corticobulbar tract: part of what system?
A
Dorsolateral system
25
Corticobulbar tract: function
Voluntary control of face muscles (precise movement)
26
Corticobulbar tract: Pathway
1. Originates in motor areas of cortex
2. Projects to and terminates on cranial nerve nuclei in the brainstem
3. Some projections terminate contralaterally and others bilaterally.
27
What plays an important role in regulating posture and equilibrium?
Brainstem
28
Brainstem nuclei act reflexively to what?
Stimuli and in response to descending info from cortex and cerebellum
29
What two ways do descending links from the brainstem affect muscle tone?
1. Links to alpha motor neurons
| 2. Links to gamma motor neurons
30
Function of descending tracts from brainstem:
Postural control; control axial and proximal muscles
31
Medial and Lateral Vestibulospinal Tracts: Part of which system?
Vestibulospinal tracts (ventromedial system)
32
What is the function of the medial and lateral vestibulospinal tracts?
Medial: Neck and upper back movement, facilitates extensors (bilateral)
Lateral: Lumbar, trunk, facilitates extensors (ipsilateral)
33
Reticulospinal tracts: function
Facilitates bilateral LMNs innervating postural and gross limb movement muscles (coordinates all 4 limbs while walking)
34
Rubrospinal tract: part of which system:
Dorsolateral system
35
Rubrospinal tract: Function
Works closely with LCT (lateral corticospinal tract) to control distal musculature (primarily upper limb flexor muscles)
36
Works closely with LCT (lateral corticospinal tract) to control distal musculature (primarily upper limb flexor muscles)
Rubrospinal Tract
37
Rubrospinal Tract: Pathway
1. Originates in red nucleus of the midbrain
2. IMMEDIATELY Decussates
3. Descends to SC to synapse on LMNS (turn off reflex arc)
38
Which tracts originate in the cortex?
1. Lateral corticospinal tract
2. Anterior corticospinal tract
3. Corticospinal tract
39
Which tracts originate in the brainstem?
1. Medial and Lateral vestibulospinal tracts
2. Reticulospinal tract
3. Rubrospinal tract
40
Just like some reflexes are mediated at the spinal level, some reflexes are mediated where?
At the brain stem
41
What are brain stem reflexes concerned with?
Posture, alignment of the head and body with respect to gravity
42
Brain stem reflexes are not neurologically intact when?
In children and adults
43
When are brain stem reflexes exhibited typically?
Developing infants
44
Can brain stem reflexes be seen in older children/adults?
Yes, but it accounts for atypical neurology or following neurological trauma when info from cortex does not reach the brainstem to modulate this reflex
45
What inhibits brain stem reflexes?
Higher centers
46
Asymmetric Tonic Neck Reflex (ATNR): Stimulus
Head turned (to right or left)
47
Asymmetric Tonic Neck Reflex (ATNR): Response (if head is turned right)
Right arm ABducted and extended, Left arm ADducted and flexed at the elbow
48
When should ATNR be inhibited by?
6 months of age in walking state
49
If ATNR is active in a child at a later age, it can affect:
1. Hand-eye coordination
2. Ability to cross midline
3. Bilateral integration (cutting, clapping, jumping)
50
Symmetrical Tonic Neck Reflex (STNR): Stimulus
Head flexion or extension
51
Symmetrical Tonic Neck Reflex (STNR): Response to head flexion
Arms flex and legs extend
52
Symmetrical Tonic Neck Reflex (STNR): Response to head extension
Arms extend and legs flex
53
What is STNR a precursor to?
Crawling on hands and knees
54
When is STNR present until typically?
8-11 months of post-natal life
55
If STNR remains present in an older child, it can affect:
1. Integration of upper and lower portions of body (swimming)
2. Sitting posture
3. Poorly developed muscle tone
4. Poor hand-eye coordination
56
UMN descend to synapse where?
| In order to convey what?
LMNs and/or interneurons in the brainstem or spinal cord in order to convey commands for movement
57
Where do UMN cell bodies originate?
Higher regions of brain (cortex or brainstem)
58
What adjusts the activity of the descending (UMN) tracts?
Control circuits
59
What is considered an UMN lesion?
Lesion in cortex, hemisphere, brainstem or spinal cord area which controls ventral horn cells
60
```
UMN or LMN motor neuron lesion?
Brain damage (stroke)
```
UMN
61
UMN or LMN motor neuron lesion?
| Damage to peripheral nerve
LMN (talk to muscles)
62
UMN or LMN motor neuron lesion?
| Damage to descending tract
UMN
63
UMN or LMN motor neuron lesion?
| Damage to motor neuron inside SC; damage to ventral root; damage to nerve
LMN
64
UMN or LMN motor neuron lesion?
| Damage to descending tract, synapsing on a motor neuron
UMN
65
What happens immediately following an UMN lesion?
Cerebral shock
| the LMNs become temporarily inactive due to loss of descending facilitation and edema in area of lesion
66
What happens following shock recovery in UMN lesion?
Interneurons and LMNs resume activity, but are no longer modulated by UMNs
67
UMN Lesion: Clinical Correlations:
1. Paresis/paralysis
2. Loss of fractionation movement
3. Atypical reflexes
68
Atypical Reflexes: Muscle Stretch Hyperflexia
Unmediated stretch reflex
69
Atypical Reflexes: Babinski Reflex
Typical in infants, pathological in adults
| Abnormal (positive) reflex: big toe extends, toes fan out
70
Atypical Reflexes: Clonus
Involuntary repeating, rhythmic contractions of a single muscle group
71
Atypical Reflexes: Clasp-Knife response
When a paretic (weak) muscle is slowly and passively stretched, resistance drops at a specific point in the ROM
(this is when a therapist would be moving the muscle)
72
Cerebral Palsy: Definition
Movement and postural disorder caused by permanent, non-progressive damage to a developing brain
73
Cerebral Palsy: Etiology
Maternal or fetal infection, hypoxia, trauma, fetal stroke
74
Cerebral Palsy: Classified by:
Type of motor dysfunction of by area of body affected
75
Cerebral Palsy: T or F, many have no additional medical disorders?
True
76
Cerebral Palsy: Associated Problems (5 things)
1. Seizures
2. Cognitive deficits
3. Language impairments
4. Visual problems
5. Spinal deformities
77
What is one of the most common forms of cerebral palsy and what age group is it often seen in?
```
Spastic Diplegia (Spastic - increased resistance to passive stretch)
Premature Infants
```
78
In spastic diplegia, what extremities are more involved?
Bilateral lower extremities more involved (affected), upper extremities are less affected
79
What form of cerebral palsy usually results from a lesion in the motor cortex (contralateral side)?
Hemiplegia
80
Hemiplegia Cerebral Palsy is often caused by:
Head trauma at birth or stroke
81
Hemiplegia Cerebral Palsy: What extremities are most affected?
Unilateral; upper extremity more involved than lower
82
What is the most severe form of cerebral palsy?
Complex/Spastic Tetraplegia
83
Which form of cerebral palsy has spasticity bilaterally in all extremities?
Complex/Spastic Tetraplegia
84
Less/More affected areas in diplegia (in pictorial representation):
```
Legs more affected
Higher area (trunk, arms) less affected
```
85
Less/More affected areas in hemiplegia (in pictorial representation):
```
One side leg and arm more affected
One side (same as leg and arm side) trunk area less affected
```
86
Less/More affected areas in Quadriplegia (in pictorial representation)
Both legs and arms more affected
| Trunk area less affected
87
Constraint-Induced therapy for Cerebral Palsy:
Less affected upper limb is restrained during session that demand use of the paretic upper limb
88
How is botox used to treat cerebral palsy?
Reduces the rigidity of muscles or unwanted spasms in a specific muscle
89
What is baclofen?
A drug used to treat cerebral palsy. It is a muscle relaxant that relieves the stiffness caused by spasticity.
90
What is a treatment for cerebral palsy that is only done in SUPER severe cases?
```
Dorsal Rhizotomy
(cuts overactive dorsal roots)
```
91
What type of cerebral palsy is dorsal rhizotomy most often used for>
Spastic Diplegia and other spastic forms of cerebral palsy
