Neuro - Muscle strength Flashcards
Muscle strength is dependent on which four factors?
- Structural
- Biomechanics
- Neural factors
- Functional factors
What is involved in the ‘structural factors’ of muscle strength?
- Size (of cross-sectional area)
- Density of muscle fibres per unit area
- Efficiency of mechanical leverage over joints
What is involved in the ‘biomechanical factors’ of muscle strength?
- Visco-elastic properties (i.e. tissues absorb energy during stretch which increases contractile force)
What is involved in the ‘neural factors’ of muscle strength?
- No. of motor units recruited
- Frequency of motor unit recruitment
- Efficiency of synergistic coordination
What is involved in the ‘function factors’ of muscle strength?
- Initial muscle length
- postural and joint stability
Which symptoms are symptomatic of an upper motor neurone lesion?
- Weakness and disuse
- Hypertonia
- Hyper-reflexia
- Spasticity
- Babinski sign
A lower motor neurone lesion could result in which symptoms?
- Flaccid muscles
- Hypotonia
- Hypo-reflexic
- Denervation atrophy
- -ve babinski sign
What are the negative signs of UMN syndrome?
- Weakness
- Decreased motor control
What are the positive signs of UMN syndrome?
- Spasticity (increased tendon reflex)
- Co-activation of muscles
- Spasms
- Clonus
- Associated reaction
What are the secondary adaptive changes in UMN syndrome?
- Increased resistance to passive movement
- Contractures
ABNORMAL MOTOR OUTPUT
What could be the reasons for an under-active agonist?
- Muscle weakness
- Secondary disuse atrophy
ABNORMAL MOTOR OUTPUT
What could be the reasons for an over-active antagonist?
- Increased tone and spasticity
ABNORMAL MOTOR OUTPUT
What could the reasons for a shortened antagonist muscle?
- Secondary biochemical changes.
