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Motor Examination Flashcards

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1
Q

What do you look for on general inspection during the motor exam

A

Posture/position
Deformities
Muscle Wasting
Spontaneous Fasciculations
Bilateral Ptosis
Facial Asymmetry
Dyskinesia (Chorea, Hemiballismus, Athetosis, Myoclonic Jerks, Tardive Dyskinesia)
Neuro-cutaneous lesions
Scars

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2
Q

What are spontaneous fasciculations

A

Visible irregular twitching of resting muscles caused by single motor units firing spontaneously

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3
Q

What are some causes of spontaneous fasciculations

A

Lower Motor Neuron Lesion

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4
Q

Explain how a lower motor neuron lesion causes spontaneous fasciculations

A

Fasciculations are as a result of denervation hypersensitivity (which occurs in severe lmn lesions)

Denervation Hypersensitivity:
When α-motor neurons are damaged, they can fire spontaneous action potentials, causing contractions in the fibres of the motor unit.

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5
Q

Fasciculations are only considered pathological when existing in the presence of which other observable features?

A

Wasting and weakness

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6
Q

What is a lower motor neuron?

A

A lower motor neuron/ alpha motor neuron is a multipolar neuron that connects UMN directly or via interneurons to the skeletal muscle that they innervate

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7
Q

Where does the cell body of an LMN lie

A

In the anterior/ventral horn of the spinal cord (CNS)

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8
Q

What are the components of a motor unit

A

LMN(anterior horn cell, axon, myelin)
Neuromuscular junction, and Muscle fibers.

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9
Q

True or false
One motor neuron will innervate several muscle fibers, but a single muscle fiber is only innervated by one motor neuron

A

True

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10
Q

What are the two main types of LMN

A

alpha motor neuron
and
gamma motor neuron

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11
Q

Within the spinal cord, where specifically do the cell bodies of Alpha motor neurons originate?

A

Lamina VIII and IX of the ventral/anterior horn

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12
Q

In terms of the muscles groups that alpha neurons innervate, how are the cell bodies arranged int the ventral horn of the spinal cord?

A

Neurons that innervate distal muscle groups are located laterally to those that innervate axial groups

Neurons that innervate extensors are located anterior to those that innervate flexors

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13
Q

What is the main function of the alpha motor neurons

A

To perform contraction

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14
Q

What portion of the reflex arc do alpha motor neurons form ?

A

The efferent arm

PS. Alpha neurons receive input from UMN and sensory nerves that form the reflex arc

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15
Q

True or False
There can be coordinated muscle contraction if the alpha motor neurons are not functioning

A

False

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16
Q

What is the function of gamma motor neurons

A

Controls muscle tone and unconscious proprioception
maintains muscle sensitivity to stretch

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17
Q

True false
A LMN syndrome involves damage to both alpha and gamma neurons

A

False, only alpha neurons are damaged in LMN syndrome

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18
Q

True or False,
γ-motor neurons are solely under control from the UMNs.

A

true

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19
Q

True or False
the firing of γ-motor neurons is directly proportional to the tone of a muscle.

A

True

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20
Q

How can tone be increased?

A

If you increased the firing of the gamma motor neurons
This hypersensitivity in turn causes greater activation and recruitment of α-motor neurons via the reflex arc, creating a stiff muscle on passive movement.

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21
Q

Define a lower motor syndrome

A

A LMN syndrome is the term used by clinicians to describe the collection of signs and symptoms present when a patient damages α-motor neurons

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22
Q

Where can the damage occur in the LMN lesion

A

Anywhere along the Brainstem nuclei/origin in the ventral horn of the spinal cord to where it synapses on the muscle fibre

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23
Q

What are 5 LMN lesion signs

A

-Hyporeflexia/Areflexia
-Hypotonicity
-Fasciculations
-Muscle Weakness/Paralysis
-Muscle atrophy

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24
Q

How does LMN lesion cause hy oreflexia/areflexia

A

The alpha motor neurons form the efferent arm of the reflex arc, therefore if they are damaged there will be no reflex contraction of the muscle group stimulated by the reflex

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25
How does LMN lesion cause hypotonia/atonia
Tone is a product of the contraction of extrafusal fibres in response to stretch. Therefore damage to the alpha motor neurons will result in decreased tone
26
What is Spinal Muscular Atrophy ?
This is an autosomal recessive disorder in which there is loss of nuclei in the ventral/anterior horn of the spinal cord. There also may be loss of motor neurons in the pons and medulla
27
Define dystonia
Dystonia is defined as sustained muscle contractions, leading to twisting, repetitive movements and sometimes tremor
28
Define chorea
Chorea describes brief, jerky, random, low amplitude, purposeless movements that may affect various body parts, commonly the arms.
29
Define athetosis
Athetosis is a slower, writhing movement, more similar to dystonia than chorea.
30
Define ballism
Ballism refers to violent flinging movements sometimes affecting only one side of the body (hemiballismus) large-amplitude, arrhythmic, and more proximal (especially at the shoulder and hip)
31
Give two causes of dystonia
Neonatal birth injury (hypoxia, brain hemorrhage) Drugs: antipsychotics, antiemetics Hepatorenal Syndrome
32
Give two causes of chorea
ST VITUS DANCE S- Sydenham's chorea T- trauma (bilateral subdural haematoma) V- vascular (infarct) I- increased RBC T- Thyrotoxicosis U- Ureamia S- SLE D- Drugs (Levodopa, carbamazepine, phenytoin) A- APLA Syndrome N- Neurodegenerative disease (Huntington's) C- Chorea Gravidarum E- Exposure to toxins (CO, Mg)
33
Causes of athetosis
Basal Ganglia disease Cerebral palsy Huntington Syndrome
34
List two causes of ballismus
neurodegenerative, vascular, toxic metabolic, infectious or immunological process affecting the basal ganglia
35
What is a tremor
This is an involuntary oscillating movement about a joint or a group of joint resulting from alternating contracting and relaxation of the muscle groups
36
What is a physiological tremor?
This is a fine (low amplitude), fast (high frequency) postural tremor
37
What are some non neurological causes of physiological tremors?
Beta Agonists Hyperthyroidism Alcohol intoxication Caffeine intake
38
Define the tremor seen in Parkinson's disease
Parkinson’s disease causes a slow (3–7 Hz), coarse, ‘pill-rolling’ tremor, worse at rest but reduced with voluntary movement.
39
Describe an intention tremor
Intention tremor is absent at rest but maximal on movement and on approaching the target
40
What is the most common cause of intention tremor
Cerebellar damage
41
In the Lower limb motor examination, what comes after general inspection?
Assessment of bulk in: Quadriceps femoris (Rectus femoris, vastus medialis, vastus lateralis, vastus intermedius) Hamstrings (biceps femoris, semimembranosus, semitendinosus) Calf muscles (gastrocnemius, soleus)
42
Which nerve innervates the quadricep femoris muscles (vastus medialis, lateralis, intermedius, rectus femoris)
Femoral Nerve (L2,L3,L4)
43
Which nerve innervates the Hamstrings (Biceps Femoris, Semitendinosus, Semimembranosus)
Tibial part of the sciatic nerve (L5, S1, S2, S3)
44
Which nerve innervates the soleus and gastrocnemius?
Tibial Nerve (L4, L5, S1, S2, S3)
45
After assessing bulk in the lower motor examination, which step is next?
Assessing tone
46
How is tone assessed in a lower motor exam?
Hip flexion/extension adduction/abduction Knee flexion/extension Ankle plantarflexion/dorsiflexion
47
Hypotonicity indicates what lesion?
LMN lesion
48
What is an UMN
An upper motor neurone (UMN) is is a neurone whose cell body originates in the cerebral cortex or brainstem and terminates within the brainstem or spinal cord.
49
Corticobulbar tracts arise and synapse where?
They arise from the pre-central gyrus and synapse at the motor nuclei of cranial nerves
50
Corticspinal tracts arise and synapse where?
They arise from the pre-central gyrus and synapse at the nuclei in the ventral horn of the spinal cord
51
What is the neurotransmitter typically involved in the transmission from upper to lower motor neurones?
Glutamate
52
What lesion causes hypertonia?(resistance to passive movement)
UMN lesion
53
How does UMN lesion cause hypertonia
UMN modulate tonicity by descending inhibition. UMN regulate inhibitory interneurons and their action on gamma and alpha (LMN). Therefore, in the absence of UMN there is no inhibition to LMN effect and results in hypertonia
54
Does UMN lesion cause hyper or hypotonicity
Descending inhibition from the UMNs also regulates the extent to which the stretch reflex is elicited (by gamma and alpha LMNs). Therefore, loss of the UMN activity causes brisk reflexes.
55
Define hypertonia
This is resistance to passive movement, not dependent on velocity
56
Define spasticity
this is a sudden increase in resistance to sudden passive movement and is velocity dependent ie (rapid passive movement of a limb, there will be a point where the muscle becomes suddenly resistant to further stretch
57
After tone is assessed in the Lower Motor examination, what is the next step?
Assessing power
58
What is the power muscle scale 0-5
0: No contractions 1: Flicker or trace of contraction 2: Active movement with gravity eliminated 3: Active movement against gravity but not resistance 4: Active movement against gravity but weaker than normal 5: Normal power
59
What is tone?
This is the resistance that the examiner feels when moving a joint passively
60
Define Rigidity
This is a sustained resistance throughout the range of movement and is most easily detected when the limb is moved slowly.
61
What is clonus?
This is a rhythmic series of contractions evoked by sudden stretch of the tendon and muscle
62
Clonus is caused by UMN or LMN lesion
UMN
63
How do UMN lesions cause clonus
Because of the decreased modulation of spinal reflexes in UMN syndrome, patients will often exhibit flexor and extensor spasms
64
What is myotonia
The inability or difficulty of muscle groups relaxing
65
Hip flexion is controlled by which muscle, nerve and nerve root
Iliopsoas Femoral Nerve L1,2,3
66
Hip extension is controlled by which muscle, nerve nerve root
Gluteal Maximus Internal Gluteal Nerve L5, S1, S2
67
Extension at the knee is controlled by which muscle, nerve, nerve root?
Quadriceps Femoris Femoral Nerve L2, 3, 4
68
Flexion at the knee is controlled by which muscle, nerve, nerve root?
Hamstrings Sciatic nerve L5, S1, S2
69
Define Huntington's Disease
This is an autosomal dominant neurogenetive disorder that is incurable and progressive. It often presents at middle age with prodromal symptoms of : irritabilty, depression. incoordination. CAused by atrophy and neuronal loss of striatum and cortex

Medicine (14 decks)

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