Lecture 26: Clinical 3: Reflexes & muscle tone Flashcards
Reflex muscle contraction when the muscle is lengthened (prevent overstretch) & consists of… _______ and ______
Reflex muscle contraction when the muscle is lengthened (prevent overstretch) & consists of:
-
Phasic stretch reflex
- Tendon jerk/reflex
- Brisk, brief
-
Tonic stretch reflex
- Passive bending – tone
- Weaker, long-lasting
Describe Tendon Jerks
- Involuntary
- Stereotyped (same jerks)
- Non-fatiguing (no decrease in power)
- Response determined by stimulus strength
- Normal v_ariations between individual_s, look for symmetry of an individual!
- ↑ by muscle activation in same segment & other muscles, called reinforcement, e.g. clenching the teeth.
- Reinforcement is used to confirm absent/reduced reflexes.
What nerve/nerve roots are associated with Jaw jerk?
Trigeminal
What nerve/nerve roots are associated with the following
Biceps
Brachioradialis (supinator)
Triceps
C5/C6
C5/C6
C6/C7
What nerve/nerve roots are associated with the following
Finger
C8
What nerve/nerve roots are associated with the following
Knee
Ankle
L3/L4
S1
Describe the Grading reflexes
Grading reflexes allows:
- Comparison between different examiners
- Reflex changes to be followed over time
If normal, relaxed shows +, reinforcement (clench teeth) shows ++.
If there was UMN lesion. what would you observe? (7)
- No wasting
- No fasciulation
- Increased tone (spasicity)
- Reduced power
- Increased tendon reflexes
- Extensor plantar response (babinski reflex)
- Rapid alternating movements is reduced
If there was a Lower Motor Neuron lesion, what would you observe?
- Some wasting
- May be fasciulations
- Normal or decreased tone (Hypotonia)
- Reduced power
- Decreased or absent t_endon reflexes_
- Flexor plantar response (normal reflex)
- Rapid alternating movements is Normal
If there was an Extra-pyramidal lesion, what would you observe?
1) No wasting
2) No fasciulation
3) Increased tone (rigidity)
4) Normal power
5) Normal tendon reflexes
6) Flexor/normal plantar reflex
7) Reduced alternating movements
What are fasciulations?
Fasciculation is a brief spontaneous contraction affecting a small number of muscle fibres, often causing a flicker of movement under the skin
What is rigidity?
Rigidity is an increased resistance to passive movement of a joint which is constant throughout the range and speed of joint displacement.
What is spasticity?
Spasticity is an increased resistance to passive movement of a joint which varies with amplitude and speed of displacement of a joint.
What are some abnormalities in reflexes?
If you see reduced or absent tendon reflexes what are SOME areas where the lesion can have occured?
- Afferent (sensory) nerve
- Cell body of motor neuron (anterior horn cell)
- Efferent (motor) nerve
- (Muscle)
What is tone?
Tone is resistance of a muscle to passive lengthening
Components of tone:
- Muscle elasticity
- Neural (tonic or stretch reflex)
Assessed by passive flexion and extension of limb at varying speeds
What are some abnormalities of tone?
Describe spasticity
Depends on the speed of muscle stretch:
- Slow stretch has little resistance;
- Faster stretch has ↑ resistance;
- Rapid stretch has ↑ resistance then sudden loss of reflex contraction (“clasp knife”).
What would you see if there were lesions in the brain?
CNS lesions result in:
- ↑ tone (spastic)
- ↑ reflexes
- ↓ sensation
- Extensor (up-going) plantar response (Babinski reflex)
- Look for symmetry on CT scan. Area of increased signal appears white. Note that coronary plexuses is white (normal).*
- Golf ball size mass affecting on right lateral ventricle. There is intracerebral haemorrhage with intraventricular extension.*
There was a lesion at the C5 of the spinal cord.
What would you observe on each of the limbs/peripheries?
Are the reflexes and tone increased/decreased?
- ↓ tone and reflexes at level of the lesion -> compress nerve roots (LMN)
- Absent biceps (C5/6) & brachioradialis (C5/6) jerks
- ↓ tone at the elbow
- ↑ tone and reflexes below the lesion -> compress spinal cord (UMN)
- ↑ triceps (C7) & finger jerks (C8)
- ↑ knee (L3/4) & ankle jerks (S1)
- ↑ tone in legs (spastic)
There is CSF (white) on each side of spinal cord (black). Loss of CSF signal at C4-6 level with spinal cord looking indented/pitched. There is a disk lesion compressing the spinal cord. Always worse on side than the other.
