Unit 3: Overview Of Motor Control/Motor Disturbances Pg. 117 - 120

Question 1

α motor neurons innervate

Answer 1

Extrafusal muscle fibers

Question 2

γ motor neurons innervate

Answer 2

Intrafusal muscle fibers in NM spindles

Question 3

Supranuclear motor control area of brain and brainstem comprised of

Answer 3

UMNs and pathways → influence LMNs (gamma reflex loop)

Question 4

The cerebellum and basal ganglia (accessory motor control areas) function by

Answer 4

Influencing other supranuclear motor control areas and UMNs in those areas

Question 5

Disturbances of motor control can be from these general categories

Answer 5

• cerebellar disturbances
• basal ganglia disturbances
• ‘pure lesion’ of pyramidal system

Question 6

De-afferent

Answer 6

To cut sensory fibers

Question 7

Interruption of sensory innervation of skeletal muscle (de-afferent) results in

Answer 7

1. No paralysis of muscle
2. Hypotonia
3. Hyporeflexia (loss of DTR)

Note: about hyporeflexia. When there is no sensory innervation, there is no sensory innervation, and no deep tendon reflex (DTR)

Question 8

What starts deep tendon reflex (DTR)?

Answer 8

Sensory information

Question 9

Lower motor neuron lesion may be caused by

Answer 9

1. Poliomyelitus (virus destroys LMNs in spinal cord ventral horn or brainstem motor nuclei)
2. Peripheral nerve injuries

Question 10

Lower motor neuron lesion results may

Answer 10

• decrease/loss in muscle tone
• paralysis or paresis of affected skeletal muscles
• weak or absent DTR
• muscle atrophy

Question 11

Upper motor neuron lesion may be caused by

Answer 11

Lesion in CNS that interrupts many descending motor control pathways that exert control on LMNs

Question 12

Unilateral UMN lesion above pyramids would result in typical signs _____ to the lesion

Answer 12

Contralateral

Question 13

Unilateral spinal cord UMN lesion below the pyramids would disrupt motor control ____ to lesion

Answer 13

Ipsilateral

Question 14

Initially during a period of spinal shock after an UMN lesion, what are the transient signs?

Answer 14

• Flaccid paralysis or paresis
• Hypotonia
• Hyporeflexia

Question 15

Eventually after a period of several weeks after an UMN lesion, what are the “permanent” signs?

Answer 15

• Voluntary movements are weak (paresis) or absent (paralysis)
• Tone of muscles is increased beyond normal = hypertonia

Question 16

Hypertonia

Answer 16

Tone of muscle is increased beyond normal

Question 17

What does hypertonia from a UMN lesion lead to?

Answer 17

Spasticity of musclesa

Question 18

Why does spasticity of muscles happen in UMN lesions?

Answer 18

A loss inhibition from descending pathways on the gamma reflex loop and the stretch reflex

Question 19

UMN lesions result in

Answer 19

Spastic paralysis of anti-gravity muscles

Question 20

Hypereflexia

Answer 20

Deep tendon reflexes are exaggerated

Question 21

After UMN lesion, limb positions will become abnormal. Upper extremity in cerebral lesion?

Answer 21

Flexed

Question 22

After UMN lesion, limb positions will become abnormal. Upper extremity in spinal cord lesion?

Answer 22

Flexed

Question 23

After UMN lesion, limb positions will become abnormal. Lower extremity in spinal cord lesion?

Answer 23

Extended (variable)

Question 24

UMN lesion limb positions

Answer 24

Uptight, spastic paralysis

Question 25

LMN lesion limb positions

Answer 25

Hanging, loose, flaccid

Question 26

In UMN lesion, only muscles of facial expression of the contralateral lower 1/2 of the face and muscles of the contralateral tongue are involved because

Answer 26

• LMNs that innervate these muscles usually receive contralateral C-B/C-N (UMN) innervation
• all other cranial nerves receive bilateral C-B/C-N (UMN) innervation

Question 27

Typical and atypical signs : Babinski sign

Answer 27

Typical: toes plantarflex
Atypical: toes (big toe) spread and dorsiflex

Question 28

Typical and atypical signs : Hoffman sign

Answer 28

Typical: no movement of fingers
Atypical: addiction or flexion of human and/or index finger

Question 29

Typical and atypical signs : abdominal reflex

Answer 29

Typical: brief contraction of muscle — umbilical moves toward stimulus
Atypical: no abdominal muscle movement

Question 30

Cremasteric reflex in infants

Answer 30

Soft touch on inner, upper thigh will result in cremaster muscle contraction

Question 31

Quadriplegia/tetraplegia

Answer 31

Paralysis of all four extremities

Question 32

Hemiplegia

Answer 32

Paralysis of half of body (L or R) both upper and lower extremity

Question 33

Paraplegia

Answer 33

Paralysis of both lower extremities

Question 34

Monoplegia

Answer 34

Paralysis of a single extremity

Question 35

Unilateral CNS lesions above pyramids results in

Answer 35

Contralateral spastic paralysis

Hemiplegia or monoplegia (depending on lesion location)

Question 36

Spinal cord lesion: complete transaction of middle cervical cord

Answer 36

Bilateral spastic paralysis
Quadriplegia
Loss of all somatosensation below level of lesion

Question 37

Spinal cord lesion: complete transaction of thoracic cord

Answer 37

Bilateral spastic paralysis
Paraplegia of lower extremity
Loss of somatosensation below level of lesion

Question 38

Spinal cord lesion: hemisection of cord

Answer 38

Called: Brown-Sequard syndrome

Motor:

• Flaccid paralysis at level of lesion on ipsilateral side
• Spastic paralysis below lesion on ipsilateral side

Loss of all Somoatosensation below level of lesion:

• ipsi loss of fine touch, prop, vibration
• contra loss of noci, temp, crude touch

Loss of noci, temp, crude touch at level of lesion — ipsi and contra sides