Phys Motor System Components Flashcards
Musculoskeletal contributions to strength reflect what?
o Length of movement arm of the muscle o Length/tension relationship of the muscle o Type of muscle fiber o Cross-sectional area of muscle o Fiber arrangement
Neural contributions to strength reflect what?
o # of motor units recruited
o Discharge frequency
o Type of motor units recruited
What is weakness in the context of neuropathology?
o Inability to generate force
o Inability to recruit or modulate motor neurons
neuropathology can lead to what?
Loss of movement, loss of power, lack of muscle activity, immobility
Neurologically-induced weakness may result from:
o Cortical lesion
o Lesion in descending pathways
o Disruption of impulses from alpha motor neurons
o Peripheral nerve injury
o Synaptic dysfunction at neuromuscular junction
o Damage to muscle tissue
T/F the extent and distribution of weakness depends on extent and location of the lesion
True
Paralysis or plegia -
total or profound loss of muscle activity
Paresis -
mild or partial loss of muscle activity
How do you name neuromuscular impairments (muscle weakness)? Mono - hemi - para - tetra -
Named by distribution mono - One single limb hemiplegia - one entire side of body paraplegia/diplegia - both legs tetraplegia - entire body
Common observations due to underlying weakness in neurologic pathology
o Postural abnormalities
o Asymmetrical weight bearing
o Abnormal Synergies
Flexor synergy -
- UE
- scapula retraction and elevation, shoulder abduction and ER, elbow flexion, supination, wrist and finger flexion
Extensor synergy -
LE
hip extension, adduction, and IR, knee extension, ankle PF and inversion, toe PF
What is tone?
Muscle’s resistance to passive stretch (certain amount of tone is normal)
Hypotonicity vs hypertonicity/spasticity
Hypo - flaccid
Hyper - rigid
Neural contributions to normal muscle tone
- Net balance of descending input on motor neurons from corticospinal, rubrospinal, reticulospinal, vestibulospinal tracts
- Sensitivity of synaptic connections
Non-neural contributions to normal muscle tone
Connective tissue plasticity and viscoelastic properties of the muscles, tendons and joints
What is spasticity/hypertonia?
Resistance to movement
Is spasticity dependent/independent of velocity?
Dependent - the faster you move muscle, the more tone you will see
-Described as clasp-knife phenomenon
Is hypertonia dependent/independent of velocity?
Independent - no matter how fast you move, it will be same tone
Spasticity occurs as result of damage to what part of spinal cord?
Pyramidal tract or other nearby descending paths
T/F Spasticity is not associated with clonus
False, can be associated with clonus (commonly in distal extremities > proximal)
How do changes in neural contributions lead to spasticity?
↓ descending activity -> reduction of inhibitory synaptic input -> increase in tonic excitatory input
T/F Spasticity results in alterations to threshold of golgi tendon reflex
False, alterations to stretch reflex
What scale used to measure spasticity?
Modified Ashworth Scale
Modified Ashworth Scale:
0 -
No increase in muscle tone
Modified Ashworth Scale:
1 -
- Slight increase muscle tone
2. Catch/release or minimal resistance at end range when moved into flex/ext
Modified Ashworth Scale:
1+ -
- Slight increase muscle tone
2. Catch followed by minimal resistance throughout remainder (less than half) of ROM
Modified Ashworth Scale:
2 -
- More increase in muscle tone through most ROM
2. BUT affected part(s) easily moved
Modified Ashworth Scale:
3 -
- Considerable increase in muscle tone
2. Passive movement difficult
Modified Ashworth Scale:
4 -
- Affected part rigid in flexion or extension
What is tardieau scale?
Measuring spasticity that takes into account resistance to passive movement at both slow and fast speeds
Tardieau scale:
V1 -
V2 -
V3 -
V1 - Slow as possible
V2 - Speed of limb falling under gravity
V3 - Fast as possible
Tardieau scale:
0 -
No resistance in passive movement
Tardieau scale:
1 -
slight resistance with passive movement
No clear catch at precise angle
Tardieau scale:
2 -
Clear catch at precise angle interrupting passive movement followed by release
Tardieau scale:
3 -
Fatigable clonus (<10 seconds when maintaining pressure) occurring at precise angle
Tardieau scale:
4 -
Infatigable clonus (> 10 sec when maintaining pressure) occurring at precise angle
What is rigidity?
heightened resistance to passive movement of the limb, independent of velocity of the stretch
Where is rigidity predominantly seen?
Flexors
What is leadpipe rigidity?
constant resistance to movement throughout entire ROM
What is cogwheel rigidity?
Alternating episodes of resistance and relaxation
Do you see posturing during movement or at rest?
At rest
What is decorticate posturing? Where would you expect a lesion to be?
-UE flexion
-LE ext/IR/PF
Lesion = brainstem above red nucleus
What is decerebrate posturing?
UE and LE extension
Lesion = below the red nucleus
T/F Tone characteristics depend on type and location of pathology
True
If you have a cortical lesion where would you expect the lesion and what type of tone would it cause?
Pyramidal (change in descending inputs of alpha motor neurons)
Spasticity (dep of velocity)
If you have a basal ganglia lesion where would you expect the lesion and what type of tone would it cause?
Extrapyramidal Rigidity (type of hypertonia - ind of velocity)
If you have a Brainstem lesion where would you expect the lesion and what type of tone would it cause?
Above/below red nucleus
Decorticate/decerebrate posturing (type of hypertonia - ind of velocity)
What is chronicity in regard to tone characteristics?
Increase nonneural changes -> increased stiffness
What are some common pathologies with hypertonicity?
CVA, TBI, MS, PD (rigidity)
What is hypotonicity?
o Reduction in resistance to lengthening; reduction in “stiffness”
Floppy hypotonicity -
collapse into gravity, harder to excite
Flaccidity -
complete loss of muscle tone
Hypotonicity is cause by:
Disruption of afferent input from stretch reflex -> lack of cerebellar efferent influence -> decreased input to gamma motor neurons
Common pathologies of hypotonicity
Cerebellar lesions, down syndrome, muscular dystrophies, late stage ALS, post-polio
ACUTE CNS injuries -> hypertonicity/spasticity once subacute/chronic
What are functional implications of increased tone?
Abnormal posturing
Misalignment
High risk for injury during prolonged rest (skin breakdown)
Bias with recruitment - Increased likelihood of synergistic movement
Destabilization with changes in position (clonus, ↑ risk for contractures)
What are functional implications of decreased tone?
Fall into gravity
High risk for injury during dynamic tasks
What is coordination?
the ability to use different parts of the body together smoothly and efficiently
What are 3 critical components of coordination?
- Sequencing
- Timing
- Grading
What is incoordination?
o Movements that are awkward, uneven, inaccurate
o Disruption of sequencing, timing, grading
Find incoordination with what type of lesions?
o Found with motor cortex, basal ganglia, cerebellar lesions (Also tied to proprioceptive lesions)
What is dysmetria?
general term for problems judging path to get to ultimate location (get to path ultimately)
Hypermetria -
overestimate/shoot the target
Hypometria -
undershoot the target
What are the functional timing difficulties with incoordination?
Increased reaction times
Slowed movement times
Difficulties terminating movement
What is the rebound phenomenon?
- Incoordination
- cerebellum lesions
- difficulty halting movement when resistance is removed
Dysdiadochokinesia
inability to perform rapid alternating movement
What is coactivation?
- Firing of both extensors and flexes at same time
- Decrease degrees of freedoms patient can move through
What is impaired inter-joint coordination?
- Cerebellum lesions
- Move one joint at a time sequentially
How do you examine incoordination?
- Multi joint movements Finger to nose Alternating pronation/supination (Dysdiadochokinesi) Hand or foot tapping Heel to shin
What are 4 involuntary movements?
- Dystonia (twisting/repetitive movements)
- Tremors
- Choreiform (jerky/rapid movements)
- Athetosis (slow twisting movements)
What is dystonia? Lesion to what area of brain? Affects what part of body?
o Basal ganglia
o Syndrome dominated by sustained muscle contractions
o Causes twisting, repetitive movements, abnormal postures
o Coactivation agonist/antagonist
o Focal, segmental, hemibody, or generalized/whole
What are tremors?
o Rhythmic, involuntary oscillatory movement of a body part
o Can be intermittent or constant, sporadic or as a sequelae to disease or injury
What is a resting tremor?
Occurs in body part that is not voluntary activated, relaxed
What is an action tremor?
Postural -
Intention -
Any tremor that is produced by voluntary contraction of a muscle
• Postural Tremor: person maintains a part of body against gravity (hold a lifted arm)
• Intention Tremor: produced with purposeful movement (sliding or lifting arm)
What is choreiform?
Seen in what syndromes?
o Involuntary, rapid, irregular and jerky movements
o Seen with Huntington’s Disease; side effect of PD medications
What is athetosis?
Is UE or LE move affected?
Common in what syndrome?
o Slow, writing and twisting movements
o UE>LE
o Common in Cerebral Palsy
Neuromuscular impairments can secondarily cause what issues?
- ROM and alignment issues
- Endurance issues
- Pain
Spasticity and hypertonia can lead to (decrease/increase) ROM?
Decrease (contractures)
Immobilization of joint can lead to (decrease/increase) stiffness?
Increased stiffness
↑ resistance to stretch, ↓ in sarcomeres -> ↑ in connective tissues
↓ rate of protein synthesis -> atrophy
Changes in length/tension relationship can do what 2 things?
Contributes to further weakness
Alters mechanical advantage
Endurance issues with neuromuscular impairments -
o Decrease in central drive to spinal cord motor neurons
o Decrease in activity level/immobility
o Presence of comorbidities - Afib, CAD, COPD, DM, etc…
Musculoskeletal pain due to:
Synergistic movements resulting in overworking of certain muscles
Muscle asymmetries causing abnormal loading through joints
ROM and alignment issues
Decreased efficiency of movements leading to increased workload required to complete tasks
