Motor System Flashcards
Leadpipe + tremor causes a series of “catches”
cogwheel rigidity
what are the 2 most commonly used medications to decrease spasticity?
baclofen and Botox
what is produced when lack of UMN control allows activation of abnormal reflex activity in spinal cord?
clonus
what are 3 effects of interrupted LMN signals?
Loss of reflexes – Atrophy – Flaccidity/hypotonia
When a paretic muscle is slowly and passively stretched, resistance drops at a specific point in the ROM
clasp-knife response
this mechanism is behind which muscle tone disorder?: loss of LMN input to skeletal muscles
flaccidity
Abnormal, PROLONGED shortening of soft tissue (not just muscle)
contractures
complete loss of muscle tone
flaccidity
velocity-dependent increase in resistance to stretch
spasticity
How muscle resists during passive stretch: less than normal resistance
hypotonia
what muscle tone disorder occurs with basal ganglia disorders and severe lesions affecting the midbrain or structures above the midbrain?
rigidity
On the MAS, what number represents: more marked increase in muscle tone through most of ROM, but the affected part is easily moved?
2
what assessment measures spasticity?
Modified Ashworth Scale
The ability to activate individual muscles independently of other muscles (essential for hand function)
fractionation of movement
On the MAS, what number represents: no increase in muscle tone?
0
which treatment for spasticity prevents LMN from releasing ACh?
Botox
abnormally low muscular resistance to passive stretch
hypotonia
basic unit of striated muscle tissue
sarcomere
when an action potential travels down a T tubule, what is released?
calcium
On the MAS, what number represents: affected part is rigid in flexion or extension (abduction or adduction)
4
what muscle tone disorder occurs with LMN disorders, severe spina bifida, floppy infant syndrome?
flaccidity
These lesions are caused by: Spinal cord injury, spastic CP, MS, stroke
UMN lesions
If testing a muscle that primarily extends a joint, place the joint in a maximally _______ position and move to a position of maximal ________ over one second
extended; flexion
If testing a muscle that primarily flexes a joint, place the joint in a maximally ________ position and move to a postion of maximal _________ over one second
flexed; extension
These lesions are caused by: Trauma, infection, degenerative or vascular disorders, tumors
LMN lesions
where would an implanted pump deliver baclofen?
subarachnoid space
what muscle tone disorder occurs with developmental disorders (trisomy 21, CP), temporarily following UMN lesions during neural shock, and LMN disorders?
hypotonia
what generally causes loss of fractionation of movement?
UMN lesions: Damage to lateral corticospinal tract
When healthy innervated muscle is continuously immobilized in a shortened position for a prolonged period, what disappear from the ends of myofibrils?
sarcomeres
what muscle tone disorder occurs with chronic UMN lesions, TBI, MS?
spasticity
what are 4 effects of UMN lesions?
Paresis/Paralysis – Loss of fractionation of movement – Abnormal reflexes – Hypertonia
what causes the LMN excessive excitability that leads to spasticity?
Absence of corticospinal inhibition to LMNs
what substance connects the M and Z lines of a muscle fiber, keeping the muscle from being pulled apart?
titin
lack of reciprocal inhibition (simultaneous firing of antagonist and agonist muscles)
co-contraction
clasp-knife response is associated with what kind of lesion?
UMN lesion
this mechanism is behind which muscle tone disorder?: decreased descending facilitation resulting in fewer weak actin-myosin bonds, excessive muscle length, decreased LMN input to skeletal muscles
hypotonia
On the MAS, what number represents: slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder (less than half) of ROM?
1+
How muscle resists during passive stretch: no resistance
flaccidity
where are the cell bodies for LMNs?
brainstem or spinal cord
How muscle resists during passive stretch: excess resistance that increases with movement
spasticity
which spasticity medication causes inhibition in spinal cord stretch reflex pathways (CNS depressant)?
baclofen
resistance to stretch present throughout entire ROM
lead pipe rigidity
How muscle resists during passive stretch: excess resistance that does not change with speed of stretch
rigidity
projections that go from superficial to deep into the muscle
Transverse tubules
velocity-independent increase in resistance to stretch
rigidity
On the MAS, what number represents: slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of ROM?
1
When an action potential is generated from a LMN, what is released?
Ach
On the MAS, what number represents: considerable increase in muscle tone, passive movement is difficult?
3
this mechanism is behind which muscle tone disorder?: direct UMN facilitation of alpha motor neurons
rigidity
what synapses with motor end plates on muscle fibers?
LMNs
a group of sacs of calcium adjacent to every T tubule
sarcoplasmic reticulum
Involuntary, repeated rhythmic contractions of a single muscle group
clonus
clonus is associated with what kind of lesions?
UMN lesions
the inhibition of antagonist muscles during agonist contraction
reciprocal inhibition
Coordinated muscular action
muscle synergies
what is the membrane called that covers skeletal muscle?
sarcolemma
this mechanism is behind which muscle tone disorder?: neuromuscular overactivity, contracture, weak actin-myosin bonds
spasticity
