3. Muscle Fnx and Analysis Flashcards
“Primary mover”
– Often considered as functional muscle group
• “elbow flexors”
– responsible for the initiation and execution of a
specific action at a joint
Agonists –
oppose or reverse the action of
the prime mover
• Antagonists –
assist the prime mover in its
actions
• Synergists –
Describe the concept of Recipricol Inhibition
Skeletal muscle functions usually includes pairs of muscles
• Depending on the muscle function one of the
pair muscles work as the agonist muscle and
the other the antagonistic muscle
For maximal muscle efficiency, speed and control
muscle pairs will:
– Increased tone in preparation for full activation
(getting the slack out)
– antagonist muscle prepares to slow down/ stop the
intended function
– The muscle pair need to coordinate their contractions to
avoid muscle injury
In neurologically intact patients, ________
reciprocal inhibition contributes to antagonist
suppression during movement
group Ia-mediated
When an individual axon is depolarized, an
_______l propagates down the nerve.
action potential
• Depolarization of all the fibers in a motor unit
creates an electrical potential called.
motor unit action potential (MUAP)
serves as the foundation for electromyography.
Analysis of the MUAPs (size, complexity, firing frequency) and assessment of baseline electrical signal at rest
How do we assess muscle function
clinically?
Manual muscle testing
• Motion analysis
• Electromyography
nerve compression, hereditary or acquired diseases, or
myopathy can be diagnosed via:
Electromyography and Nerve Conduction Studies
________ studies test motor, sensory, mixed
nerves
Nerve conduction
__________ tests skeletal muscle fibers
• Standard needle electromyography mostly tests type I
muscle fibers
Electromyography
MUAPs generated by contraction of an individual
muscle can be recorded by using
a surface or needle electrode
This information can be used to monitor that muscle’s activity during a certain action and to assess the integrity of the muscle and the nerves supplying it.
MUAPs from individual muscle contraction
Nerve conduction studies are a component of
electromyography. These studies assess
the integrity of the peripheral nervous system.
Number of muscles fibers innervated by a
single axon/motor neuron = innervation ratio
Description of motor unit
– Varies widely between muscles – Low for fine motor • Extraocular muscles – High for gross motor • Soleus
Motor unit
Size principle
During motor unit recruitement, larger MUs are recruited later
Lesion of the upper motor neuron in the central
nervous system occur in the Brain or Spinal cord. Cause what type of signs
Overactivity or “Positive Signs” – Hyperreflexia – Spasticity • Underactivity or “Negative Signs” – Weakness • No inherent muscle atrophy
Overactivity or “Positive Signs” – Hyperreflexia – Spasticity • Underactivity or “Negative Signs” – Weakness • No inherent muscle atrophy
UMN lesion
Velocity-dependent increase in tonic stretch reflex
(muscle tone)
• Hyperexcitability of the stretch reflex
• One component of the upper motor neuron
syndrome
• Decreased reciprocal inhibition
Spasticity
Intra-muscular injections can be used to reduce
focal muscle overactivity
• Affects both intrafusal and extrafusal muscle
• May affect nociceptor pathways via C and A
delta fibers and substance P as well
Botulininum Toxin
• Can be used to block salivary and sweat gland
• Used to treat numerous disorders: dystonia,
spasticity, ophthalmologic, GI/GU, dermatologic
and pain.
Botulininum Toxin
Mech of Botulininum Toxin
Gets internalized and cleaves SNAP 25
Needle EMG test
Type I fibers
