Neuro: Cortiospinal Motor System: Dip And Weak

Question 1

What are the two consecutive neurons in the Corticospinal motor system?

Answer 1

Upper motor neuron and lower motor neuron

Question 2

Where is the UMN located?

Answer 2

Pre central gyrus

Question 3

Where is the LMN located

Answer 3

Ventral/anterior horn

Question 4

LMN project to muscle from the ventral horn via ____ ____

Answer 4

Peripheral nerves

Question 5

Neuroanatomical pathway:

Answer 5

1. UMN cell bodies in PrecentralGyrus.
2. Axons descend through Cerebrum in a white
   matter tract called the Internal Capsule.
3. Axons continue to descend through brainstem levels, including through the Pyramids of Medulla.
4. Most UMN axons cross the midline to the
   opposite side at the Pyramidal Decussation in Medulla.
5. UMN axons continue to descend down Lateral CorticospinalTract (LCST) until they reach their target level of the spinal cord, i,e, their target LMNs.
6. Axons exit the LCST and terminate (synapse) on LMN in Anterior (Ventral) Horn.
7. LMN projects out anterior (ventral) roots and via peripheral nerve to muscle.

Question 6

The precentral gurus is the _____ cortex

Answer 6

Motor cortex

Question 7

UMN damage at the pre central gurus: possible pathologies

Answer 7

-Amyotrophic lateral sclerosis
-Cerebral palsy(hypoxia/ ischemia)
-Ischemic stroke

Question 8

UMN damage at the pyramidal decussation: possible pathologies

Answer 8

-Brain stem infarcts(UMN axons)
-mass growing

Question 9

UMN damage at the spinal cord: possible pathologies

Answer 9

-white matter disease
-injury/infarct/mass

Question 10

LMN damage can occur at

Answer 10

Spinal cord, muscle, neuromuscular junction, peripheral nerves

Question 11

If the corticospinal tract is damaged superior to pyramidal decussation produces

Answer 11

Limb paresis or paralysis on side contra lateral to the lesion

Question 12

Lateral corticospinal tract damage inferior to the pyramidal decussation produces

Answer 12

Paresis or paralysis on side ipsilateral to the lesion

Question 13

Damage to the pyramidal decussation produces

Answer 13

Bilateral paresis or paralysis

Question 14

Damage only to the ventral/anterior horns typically produces

Answer 14

Segmental pattern of weakness

Question 15

Damage only to the lateral corticospinal tract produces a

Answer 15

Level-down pattern of weakness

Question 16

Rating of neurological exams

Answer 16

5 / 5 Normal strength, can overcome resistance from examiner
4 / 5 Limited ability to overcome resistance
3 / 5 Movement does not overcome resistance, but can overcome gravity
2 / 5 Movement does not overcome gravity or resistance (horizontal only)
1 / 5 Muscle contraction visible without movement
0 / 5 No contraction, no movement

Question 17

Stretch reflex or deep tendon reflex rating in neuro exam

Answer 17

4 / 4 Clonus, (rapid alternating contractions, e.g. flexion / extension)
3 / 4 Brisk (slightly excessive in magnitude or speed)
2 / 4 Normal***
1 / 4 Trace (barely detectable)
0 / 4 Absent reflex

Question 18

The patellar reflex is mediated by ____ _____

Answer 18

Muscle spindles

Question 19

patellar reflex pathway

Answer 19

① Tap on patellar tendon creates mild stretch in quadriceps muscles.
② Stretch detected by sensory neuron
fibers wrapped around spindle muscle
fibers.
③ Sensory neuron fires, releases
excitatory neurotransmitter on
motorneuronthat activates
contraction of quadriceps muscles.

Question 20

Stretch reflex can also be activated by ______ stretch by the examiner which activates _____ ____.

Answer 20

Passive, muscle spindles

Question 21

Sensory arc for muscle spindles

Answer 21

Stretching muscle spindle fibers activate sensory neurons that are wrapped around muscle fibers

Question 22

Motor arc for muscle spindles

Answer 22

Sensory fibers form excitatory synapses on alpha motor neurons to activate muscle contraction and movement

Question 23

the patellar reflex tests which spinal cord level?

Answer 23

L4

Question 24

The shoulder reflex tests which spinal cord level

Answer 24

C5

Question 25

The brachioradialis reflex tests which spinal cord level

Answer 25

C5-C6

Question 26

The triceps reflex tests for which spinal cord level

Answer 26

C7

Question 27

What are the four most common stretch reflex tests

Answer 27

Biceps Brachioradialis Triceps Knee jerk(patellar)

Question 28

LMN lesion signs - Strength: Muscle tone: Stretch reflexes: Atrophy: Other signs:

Answer 28

Strength:decreased Muscle tone: decreased Stretch reflexes:decreased Atrophy: severe Other signs: fasciculation’s

Question 29

UMN lesion signs Strength Muscle tone Stretch reflexes Atrophy Other signs

Answer 29

Strength: decreased Muscle tone: increased Stretch reflexes:increased Atrophy:mild Other signs: clonus, pathological reflex (babinski)

Question 30

Fasciculation definition

Answer 30

Spontaneous contractions of groups of muscle fibers visible as muscle twitches

Question 31

Clonus definition

Answer 31

A series of alternating and opposite muscle group contractions in response to muscle stretch by the examiner Exaggerated response to passive stretch stimulus

Question 32

What is babinkski’s sign

Answer 32

Foot extends and toes fan out in response to touching the bottom of foot -normal response is toe flexion

Question 33

LMN signs are described as ____ weakness

Answer 33

Flaccid weakness

Question 34

UMN signs are described as ___ weakness

Answer 34

Spastic

Question 35

If both LMNs and UMNs are damaged, patient shows ___ signs

Answer 35

LMN

Question 36

LMN must be _____ for UMN signs to occur

Answer 36

Intact

Question 37

The exaggerated reflexes of UMN lesions signs is due to

Answer 37

LMN trying to compensate for the lack of stimulus from UMN

Question 38

If there is a lesion on the entire pre central gurus on the patients left side: Where is the weakness UMN or LMN

Answer 38

Where is the weakness: right side UMN

Question 39

If there is a lesion on the internal capsule on the patients right side: Where is the weakness: UMN or LMN:

Answer 39

Left side UMN

Question 40

If there is a lesion in the corticospinal tract in the brain stem, patient’s left side: Where is the weakness: UMN or LMN:

Answer 40

Right side UMN

Question 41

If there is a lesion on the pyramidal decussation at the midline: Where is the weakness: UMN or LMN:

Answer 41

Bilateral UMN

Question 42

A lesions at the lateral corticospinal tract @ C5, patients right side: Where is the weakness: UMN or LMN: Segmental or level-down Pattern:

Answer 42

Right side UMN Level-down

Question 43

A lesion on the anterior horn @ C5, patient’s right Where is the weakness: UMN or LMN: Segmental or level-down Pattern:

Answer 43

Right side LMN Segmental

Question 44

A lesion or neuropathy on the peripheral nerves would cause:

Answer 44

- mixed motor and sensory deficits -Nerve conduction testing, hand-held device

Question 45

lesion of the neuromuscular junction disorder would cause____ _____ issues

Answer 45

pure motor

Question 46

What is Myasthenia Gravis?

Answer 46

Neuromuscular junction disorder Antibodies vs Nicotinic Ach receptors, “fatigue able weakness”

Question 47

What is Lambert-Eaton disorder?

Answer 47

Neuromuscular junction disorder Antibodies vs Ca++ channels Pattern: weakness can improve with activity