Class 3 Flashcards
Muscle cramps commonly involve what part of the body?
Calf, foot, thigh
What is observed during and immediately after a muscle cramp?
A hard knot
Muscle cramps are characterized by
Sudden onset of painful, involuntary squeezing or contraction of muscle
Constant muscle cramps are indication of what?
High frequency stimulation
Observation of hard knot after cramp occurs could indicate what?
Deficiency in muscle relaxation, could be cytosolic Ca or ATP concentration
- High frequency of stimulation
- Cumulation of cytosolic Ca
- Constant muscle contraction
During muscle cramps
- Lack of ATP
- Deficiency of SERCA
- Cytosolic Ca remains high
After muscle cramps
Appearance of hard knot in affected muscle could be an indication of (-) depletion
ATP
Can speed of relief of muscle cramps by:
- stretching affected muscle
- contraction of its antagonist muscle
In muscle cramp, (-) is not getting to the muscle, resulting in no (-) in the muscle to allow it to relax
Oxygen, ATP
After muscle cramps, some symptoms are
- soreness
- swelling
Elevated serum creatine kinase (CK) indicates
Skeletal muscle damage, or muscle cramps
Muscle cramps can cause what kind of damage to muscle?
Hypoxic/metabolic damage
Two hypothesis for causation of muscle cramps
- dehydration and electrolyte depletion
- neuromuscular
Triggering factors of muscle cramps - dehydration and electrolyte depletion
- sweat loss
- pH disturbances
- thermal strain
Stretch receptors that can be found in the capsules of the extrafusal muscle fibers are
Muscle Spindles
Triggering factors of muscle cramps - neuromuscular hypothesis
- muscle fatigue
- motor neuron disease (like ALS)
- changes in electrolyte concentration or mechanical effects
Onset of muscle cramp requires what?
Alpha motor neuron to fire in high frequency
Sequence of events for neuromuscular hypothesis
- triggering factors
- increase afferent sensory neuron excitability
- increase alpha motor neuron firing frequency
- increase frequency of muscle contraction
- muscle cramp
For muscle contraction is it very necessary for (neural or physiological) control?
Neural
EMGs are used to look at muscles after muscle cramps and can show
Involuntary repetitive high frequency firings of the motor neuron that innervates the cramping motor unit
High frequency firings of the motor neuron can mean what?
Leakage in Ca
EMG data suggests muscle twitch are of peripheral nerve origin (T/F)
True
Why are muscles in the lower extremities effected more?
Longer axon in lower limb, the longer it is the more damage that can happen
Who is more frequently affected with muscle cramps?
- Pregnant women
- Elderly people
- People with thyroid disease
- People with liver disease
Why are elderly more effected by muscle cramps?
Effected by mild loss of motor neurons
Why are pregnant people more effected by muscle cramps?
Physical distortion of neuromuscular junction as byproduct of fluid retention and joint laxity
Why are those with thyroid disease/hypoadrenalism affected with more muscle cramps?
Adrenal gland controls electrolyte balance by sodium uptake, pH effected
Why are those with liver disease and cirrhosis effected with muscle cramps?
Could be decrease in intravascular volume and edema
Neurophysiology of muscle cramps are related to what?
Somatic motor neuron
When are muscle spindles firing?
Constantly, they are tonically active
Sensory neuron spans
The length of the muscle
Impulses on somatic motor neuron has a (higher, lower) frequency than that of descending tract of the axons within spinal cord
Higher
Maintaining tension at rest shows
Muscle tone
Impulses from sensory neuron originate from where?
Muscle spindle
Impulses from sensory neuron will integrate from (-) at the level of (-)
Brain, spinal cord
Stretching of extrafusal muscle will also stretch
Muscle spindles
Alpha motor neuron activation process
- Alpha motor neuron fires
- Muscle contracts
- Less stretch on center of intrafusal fibers
- Firing rate of spindle sensory neuron decreases
Stretching helps muscle cramps which is mediated by:
Central Inhibition
What induces involuntary repetitive high frequency firings of the motor neuron that innervates the cramping motor unit
Stretching
Further increase in frequency of impulses to the stretched muscle through
The alpha motor neuron
