tone

Question 1

2

normal muscle tone

Answer 1

• sufficient tension to allow movement but maintian stability
• varies with posture and …?

Question 2

2

what provides normal muscle tension?

Answer 2

• neural - firing of nerves active muscle contraction and background activity even when the muscle is relaxed
• non-neural- non-elastic structures within the muscle tendons; elastic properties and connective tissues

Question 3

between 3 things

what interaction maintains tension?

Answer 3

extrafusal muscle fibres, spindles and golgi tendon organs

Question 4

extrafusal muscle fibres

Answer 4

comprise the main bulk of muscle and form the major force-generating structure

Question 5

3 where, contain?

intrafusal muscle fibers

Answer 5

• buried in the muscle
• contain the muscle spindles (afferent receptors for stretch)
• contain contractile elements

Question 6

2

reciprocal inhibition basic principle

Answer 6

1. when a muscle spindle is stretched and the stretch reflex is activated
2. the opposing muscle group must be inhibited to prevent it from working against the resulting contraction of the homonymous muscle

Question 7

how is inhibition acomplished?

Answer 7

by an inhibitory interneuron in the spinal cord

Question 8

reciprocal inhibition

what divides in the spinal cord

Answer 8

1. The 1a afferent of the muscle spindle

Question 9

where do the branches go and wha do they do

Answer 9

• One branch innervates the alpha motor neuron that causes the homonymous muscle to contract, producing the reflex.
• The other branch innervates the 1a inhibitory interneuron, which in turn innervates the alpha motor neuron that synapses onto the opposing muscle.

Question 10

what does the interneurone prevent and why

Answer 10

• it prevents the opposing alpha motor neuron from firing, thereby reducing the contraction of the opposing muscle.
• Because the interneuron is inhibitory

Question 11

5, 6 med

extrinsic factors affecting tone

Answer 11

1. posture (BoS, CoG)
2. temperature
3. visual or auditory stimuli- affect alert state
4. emotional states e.g anxiety
5. medical factors
   * UTI’s
   * bowel impactation
   * skin irritation/ ulceration
   * ingrown toenail
   * increased sensory stimuli (clothes or orthoses)
   * pain

Question 12

3

model of abnormal motor output

Answer 12

1. under-active agonist
2. over active antagonist
3. shortened antagonist

Question 13

model of abnormal motor output 2

Answer 13

over active antagonist
- increased tone/ spasticity
- may still be weak due to lack of voluntary drive

Question 14

model of abnormal motor output 3

Answer 14

shortened antagonist
- stiffness and contracture

Question 15

secondary adaptive changes UMN lesion

Answer 15

• mechanical muscle stiffness
• contractures (decreased range of movement)

Question 16

Clinical presentation of UMN syndrome

weakness (underactive)

Answer 16

low tone

Question 17

Clinical presentation of UMN syndrome

spasticity (overactive)

Answer 17

High tone
neural

Question 18

Clinical presentation of UMN syndrome

2nd adaptive muscle and soft tissue

Answer 18

high tone
**non- neural **

Question 19

Nerve impulse

Answer 19

• a small electrical potential generating a current that travels rapidly along the nerve fibre (See health sciences module for nerve conduction, velocities, nodes of ranvier, saltatory conduction etc.)

Question 20

voluntary movement

Answer 20

• initiated by nerve impulses arising in the pre-motor and motor cortex.
• complex interconnecting pathways connect the brain with the muscles to generate movement.
• Feedback to the brain and spinal cord from many and varied types of sensory receptors enables movement to be controlled.

Question 21

Voluntary movement by definition

Answer 21

involves the conscious brain, but the basic building block of movement is the spinal reflex, onto which higher centres exert control. More about reflexes later.

Question 22

why can brain lesions cause symtoms on the opposide side of the body

Answer 22

some nerve impulses travel directly from the motor cortex to the spinal cord – pyramidal tracts (corticospinal tract) - majority cross over in the brain so that the right side of the brain controls the left side of the body and vice-versa – example stroke. Impulses arising in other parts of the brain, e.g. reticular formation, cerebellum, do not.

Question 23

spasticity definitions

Answer 23

• velocity depended increase in tonic stretch reflexexs as one component of the upper motor neuron sydrome
• disordered sensory-motor control, resulting from upper motor neuron lesion, presenting as intermittent or sustained involuntary activation of muscles

Question 24

what is spasticity

Answer 24

• innapropriate muscle activity- often presents itself as an axaggerated stretch reflex or co-activation of opposing muscel groups

Question 25

stretch reflex

Answer 25

* When muscle is stretched * firing of the 1a afferents * The 1a afferents have their cell bodies in the dorsal root ganglia of the spinal cord * send projections into the spinal cord, and make synapses directly on alpha motor neurons * that innervate the same (homonymous) muscle. . **Thus, activation of the 1a afferent causes a monosynaptic activation of the alpha motor neuron that causes the muscle to contract.** stretch reflex is activated, it not only causes contraction of the synergistic muscles, but also caused relaxation i.e. has an inhibitory effect on the antagonist muscles.

Question 26

under-active agonist

Answer 26

* derease neural drive to spinal neurons * muscle weakness/low tone

Question 27

over-active antagonist

Answer 27

- increased tone/ spasticity - may still be weak due to voluntary drive

Question 28

shortened antagonist

Answer 28

stiffness and contracture

Question 29

# assessment handling

Answer 29

* Avoid over handling reflex stimulating surfaces e.g. ball of foot and palm of hand * Use lumbrical grasp with firm contact throughout your whole hand i.e. avoid gripping with finger tips, so that its supportive but not painful (which would stimulate reflex response) * Make sure hands are warm as temperature really affects neuro patients

Question 30

# assessment Passive range of motion

Answer 30

* Consider starting position, ideally well supported in supine to ensure accuracy and patient able to relax with minimal associated reactions or compensatory movement * Slowly move the joint through range, apply small traction force * Watch patient’s face * Make sure you know your anatomy and biomechanics – how far should this joint move? What is the normal range? Are there any muscles limiting ability to assess joint range specifically? * Take care with low tone joints – e.g. risk of damage / pain GH joint post-stroke * Take care if poor sensation – e.g. risk of joint damage if reduced proprioception * What is the ‘feel’ during movement? How much resistance? Does this change through range? Is there a catch? * What is the ‘feel’ at end of range?

Question 31

Assessment of hypertonia (spasticity):

Answer 31

* Hypertonicity (spasticity) is present if resistance through range increases as speed increases or if a "catch" occurs as the velocity becomes fast enough * Sometimes there is also a "clasp-knife" response, this is where following the initial catch, there is a sudden reduction in resistance and movement returns through the rest of the available range * Rapid passive movements may also elicit spasm or clonus of muscle being stretched * Patients starting posture will affect result i.e. muscles partially stretched are more likely to elicit reflex e.g. hamstrings demonstrate greater reflex activity if start in hip flexion rather than hip extension * Recording the influence of starting posture on reflex response is important (it will also influence the starting postures used in treatments) * Consider other relevant factors i.e. tight clothing, medication, noxious stimuli (i.e. UTI)

Question 32

upper limb tone hypertonia test

Answer 32

* Elbow flexors * Wrist flexors

Question 33

lower limb hypertonia test

Answer 33

* Ankle plantar flexors (knee extension and knee flexion) * Knee extensors

Question 34

assess clonus in lower limb

Answer 34

* Ask patient to relax * Support the knee in a partly flexed position * Quickly dorsiflex the foot and observe for rhythmic clonic movements * More than three rhythmic contractions of the plantar flexors is a positive response and indicates an UMN lesion

Question 35

initial assessment

Answer 35

in supine as it lowers tone and is a good position for patient and therapist Assess again in sitting and in walking