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52 Cards in this Set

  • Front
  • Back
In terms of paralysis, describe the difference btw the LMN and UMN lesions.
LMN is flaccid paralysis

UMN is spastic paralysis
Which motor neurons does ALS attack?
UMN have projection neurons going from where?
Layer V of cerebral cortex
What are the pathways of the UMN?


What type of movement is UMN responsible for?
Where are most UMN located?
Motor/Premotor cortex
How does UMN control LMN?
Via interneurons in the intermediate zone
What type of Pyramidal UMNs (in the Motor cortex) bypass the intermediate zone, allowing for direct connections with LMN?

What does this mechanism control?
Betz cells

Hand movement
What are the components of the pyramidal tracts?
Corticobulbar tract

Corticospinal tract
In the midbrain, the majority of pyramidal tract crosses over where?
Caudal Medulla
In the corticospinal tract, what is the major pathway for voluntary muscle?
Lateral Corticospinal tract.
What does the lateral corticospinal tract have exclusive control over? and how?
Intrinsic muscles of hand.

Via UNN-LMN connection (no interneurons)
Is the lateral corticospinal tract a crossed pathway?
Is the anterior corticospinal tract a crossed pathway?
Yes, but it is also uncrossed too.
What does the anterior corticospinal tract control?
Proximal musculature on the ipsilateral and contralteral side, chiefly in the upper body
Where in the spine does the corticobulbar cross over?
Never goes into spine.

Just pons and medulla.
Is the corticobulbar tract crossed?
Majority is crossed, but some uncrossed also.
What areas does the corticobulbar tract control?
Face and Oral Cavity
Where do corticobulbar neurons cross usually?
At the level of the cranial nerve nucleus being innervated.
Which portions controls the lower part of the face?
Only the CROSSED over portions of the corticobulbar
The majority of corticobulbar axons control LMN in which cranial nerves?
Facial (CN VII - facial expression)

Vagus (CN X)

Hypoglossal (CN XII - speech)
What are the components of the extrapyramidal pathways?
Rubrospinal tract

Reticulospinal tract (medial/lateral)
Is the rubrospinal a crossed pathway?
What does the rubrospinal tract control?
Strong EXCITATORY effect on PROXIMAL flexors of the upper extremity.
Is the medial reticulospinal tract crossed?
Yes, but also uncrossed too.
What is the Major Alternate Pathway, and what does it control?
Medial reticulospinal tract.

Controls axial and proximal musculature.
What pathway has a strong excitatory effect on anti-gravity musculature (axial and extensor musculature)?
Medial reticulospinal tract.
Is the lateral reticulospinal tract crossed?
Yes, but also uncrossed too.
What does the lateral reticulospinal tract control?
Variety of excitatory and inhibitory movements on axial and proximal limb muscles.
Where does the lateral reticulospinal tract cross over?
Spinal cord
Unilateral lesions may result in incomplete paralysis. Why?
Due to pathways being crossed and uncrossed.

Also, due to the Major Alternative Pathway
Describe the motor cortex's evocation of muscle.
Evokes movement of individual muscles

based on homonculus
Describe the threshold for the M1 (Motor Cortex)
Describe the threshold for the M2 (Premotor Cortex)
Describe the Premotor cortex's evocation of muscle.
Evokes mass muscle movements

involving postural adjustments

ipsilaterally and contralaterally
What is the supplementary motor cortex?
The medial surface of M2
Most axons of the pyramidal tract originate where?
Motor Cortex
Most axons of the extrapyramidal tract originate where?
Premotor cortex
Lesions in the M2 usually leads to what?
Contralateral spasticity of antigravity muscles

due to loss of inhibition by UMN
The supplementary motor area evokes what type of movement?
Bilateral and sequencing of motor activity
What are the possible lesion sites for the UMN?
Internal capsule
Spinal cord
UMN lesions usually result in what type of symptoms?
1. Spastic paralysis (hemiplegic/hemiparesis)

2. Muscle weakness with Pronator drift (on paretic side)

3. Abnormal reflexes

4. Loss of speed and agility (on paretic side)

5. Loss (complete) of control over distal muscle (intrinsic hand muscles)
List the abnormal reflexes associated with UMN lesions.
1. Clonus
2. Hoffman's sign
3. Increased DTR
4. Clasp-Knife reflex
5. Babinski sign
6. Superficial reflexes lost.
Describe the effects of UMN lesions to the Lower Extremity.
Extensor Hypertonia

Gait: stiff, spastic, with circumduction at hip joint.
Describe the effects of UMN lesions to the Upper Extremity.
Flexor hypertonia

with paralysis of intrinsic hand muscles,

but grasping movement may be spared.
A DTR of 0 would indicate a lesion where?
A DTR of +1 would indicate a lesion where?
LMN and Cerebellar
A DTR of +2 would indicate a lesion where?
none. it is normal
A DTR of +3 would indicate a lesion where?
A DTR of +4 would indicate a lesion where?
Describe a DTR of +4
Hyper reflex with clonus
A babinski sign would indicate a lesion in which tract?
Pyramidal - Lateral Corticospinal tract.