Motor Systems Components Flashcards
What are some primary neuromusclar impairments that can result from a neurological pathology?
- Muscle weakness
- Abnormal tone
- Coordination deficits
- involuntary movements
What are some secondary neuromusclar impairments that can result from a neurological pathology like an UMN lesion?
- ROM and alignment issues
- Endurance issues
- Pain
how would you define muscle weakness as a neuromusclar impairment?
inability to generate force or recruit/modulate motor units
list some neural contributions that can result in the primary neuromusclar impairment of muscle weakness
Change in:
- # of motor units recruited
- D/C frequency
- type of motor unit recruited
What are some potential neurological pathologies that can result in neuromusclar weakness as an impairment?
- Cortical lesions
- lesions in descending pathways
- disruption of impulses to alpha motor neurons
- peripheral nerve injury
- synaptic dysfunction at NMJ
Muscle weakness as a neurological impairment can result in what secondary impairments/observations?
- postural abnormalities
- asymmetrical weight bearing
- abnormal synergies
list 2 types of abnormal synergies
- Flexor synergy (UE)
- Extensor synergy (LE)
describe a flexory synergy?
scapular retraction and elevation
shoulder abduction and ER
elbow flexion
supination
wrist and finger flexion
describe an extensor synergy
hip extension, adduction and IR
knee extension
ankle PF and inversion
toe PF
what is tone?
muscles’ resistance to passive stretch
Describe the continuum/varying levels of tone
From too little to too much
- Flaccid
- Hypotonicity
- normal
- hypertonic/spasticity
- Rigid
what are the neural contributions to normal tone?
net balance of descending input on motor neurons from:
corticospinal tracts
rubrospinal tracts
reticulospinal tracts
vestibulospinal tracts
as well as the sensitivity of synaptic connections
what are the non neural contributions to normal tone?
- CT plasticity
- viscoelastic properties of the muscles, tendons, and joints
How is spasticity different from hypertonia?
spasticity is velocity dependent and hypertonia is not
Spasticity can sometime be described as a ___________
clasp-knife phenomenon
what is a typical cause of spasticity and a common result/association?
damage to pyramidal tract or other nearby descending paths
can be associated with clonus (commonly in distal > proximal extremities)
Describe the mechanism by which spasticity occurs
- changes in neural contributions
- results in decreased descending activity
- reduction of inhibitory synaptic input
- increases tonic excitatory input
- results in alterations to threshold of stretch reflex
List 2 scales typically used to measure tone
- Modified Ashworth Scale
- Tardieu scale
which scale used to measure tone, also gives us info on spasticity?
Tardieau
since we vary the velocities (V1, 2, 3)
which applied velocities equate to spasticity on the Tardieau scale?
V2 = speed of limb falling under gravity
V3 = fast as possible
In what muscle group is hypertonia typically observed?
Flexors
When testing hypertonia with movements, it can be described as _________ or _________
leadpipe or cogwheel
what is the difference between leadpipe and cogwheel hypertonia?
leadpipe = constant resistance to movements throughotu entire ROM
Cogwheel = alternating episodes of resistance and relaxation
what is hypertonia at rest called?
Posturing
What are the 2 types of posturing?
decorticate = UE flexion, LE extension/IR/PF
decerebrate = UE and LE extension
what type of posturing is due to a lesion at or above the level of the red nucleus?
decorticate posturing
characteristic of the tone abnormality depends on what factors?
- type and location of pathology
- Chronicity
- increases in nonneural changes = increased “stiffness”
List the type of abnormal tone that would result if a lesion occured at the cortical, brainstem, and basal ganglia level?
- cortical: pyramidal → change in descending inputs of alpha motor neurons → spasticity
- Basal ganglia: extra pyramidal → rigidity
- brainstem: above/below red nucleus → decorticate/decerebrate posturing
List some pathologies in which hypertonicity is commonly observed
- CVA
- TBI
- MS
- Parkinsons Disease (rigidity)
define hypotonicity
reduction in resistance to lengthening
reduction in “stiffness”
hypotonicity can be described as _______ or _______
floppy = collapse into gravity, harder to excite
flaccidity = complete loss of muscle tone
what causes hypotonicity?
disruption of afferent input from stretch reflex →
lack of cerebellar efference influence →
result in decreased input to gamma motor neurons
List some pathologies where hypotonicity is commonly observed
- Cerebellar lesions
- down syndrome
- musclar dystrophies
- late stage ALS
- post-polio
- Acute CNS injuries → typically end up resulting in hypertonicity/spasticity once subactue phase is over
what are the functional implications for 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, increased risk for contractures)
what are the functional implications for decreased tone?
- fall into gravity
- high risk for injury during dynamic tasks
define coordination
ability to use parts of the body together smoothly and efficiently
what are the critical components of coordination?
- sequencing
- timing
- grading
define incoordination
movements that are awkward, uneven, inaccurate
disrupting of sequencing, timing and grading
loss of coupling between synergistic joints and muscles
incoordination is typically observed with what types of lesions?
motor cortex
basal ganglia
cerebellar
(proprioceptive lesions too)
the functional implications of incoordination can be divided into what categories?
- grading/scaling dysfunction
- timing difficulties
- activation and sequencing problems
what are the types of grading/scaling dysfunctions found with incoordination?
- dysmetria = under/overshooting intended position (a type of ataxia)
- hypermetria = moving beyond intended goal
- hypometria = moving short of intended goal
list some timing difficulties that are a result of incoordination
- increased reaction times
- slowed movement times
- difficulty terminating movements
- rebound phenomenon
- dysdiadochokinesia
list some activation and sequencing problems that occur with incoordination
- abnormal synergies
- coactivation
- impaired inter-joint coordination
what are the components of the coordination examination?
- finger to nose
- alternating pronation/supination
- hand or foot tapping
- heel to shin
List several categories/types of involuntary movements that are primary neuromusclar impairments
- dystonia
- tremors
- choreiform
- athetosis
what is dystonia?
syndrome dominated by sustained muscle contractions
causing twisting, repetitive movements, and abnormal postures
what region of the brain is dystonia correlated with?
basal ganglia
what are tremors?
rhythmic, involuntary oscillatory movement of a body part
can be intermittent or constant, sporadic or as a sequale to a disease or injury
what is the difference between a resting and active tremor?
resting = occurs in a body part that is not voluntarily activated (it’s relaxed)
active = any tremor produced by voluntary contraction of muscle (can be postural or intention)
what is a postural tremor? Intention tremor?
postural = person maintains a part of body against gravity
intention = produced with purposeful movement
what is a choreiform?
involuntary, rapid, irregular and jerky movements
seen with Huntingtons disease and is a SE of PD meds
what is athetosis?
slow, writhing and twisting movements
UE > LE
common in CP
What causes endurance issues to be a secondary neuromuscular impairment?
- decrease in central drive to spinal cord motor neurons
- decrease in activity level/immobility
