Lecture 20 (4/16) Flashcards Preview

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Flashcards in Lecture 20 (4/16) Deck (10):

Damage to the Lower Motor Neurons


1. Paralysis or diminution of movement

2. Decrease in muscle tone - hypotonia

3. Loss of tendon reflexes

4. Atrophy

5. Fibrillations (tremors) and/or fasciculations (spontaneous activity of muscle fibers)


Damage to the Upper Motor Neurons


1. Paralysis, diminution of movement

2. Spasticity - increased muscle tone

3. Overactive tendon reflexes

4. Atrophy is rare in UMNs and there are no fasciculations

5. Abnormal extensor reflexes
-Babinski Sign


Babinski Sign

Pen on bottom of foot

In typical person toes go down, in a person with damage to the UMNs there will be a fanning of the toes upward


Amyotrophic Lateral Sclerosis (ALS) (Overview)

Etiology is unknown

Death is approx. 3 years after onset

Patients with ALS speak with a great deal of effort, which intensifies as the disease progresses


ALS (Specifics)

In ALS both UMNs and LMNs are damaged

Pathology is caused by atrophy of the ventral horn cells (LMNs)

Sclerosis of the anterolateral columns and pyramidal columns

Deterioration of cranial nerve nuclei at the level of the medulla


Right Spastic Hemiplegia

Hemiplegia means one sided paralysis, Hemiparesis means one sided weakness

Contralateral because damage occurs to the UMNs


Corticobulbar Tract

Provides motor input to the cranial nerves' nuclei (LMNs)

The corticobulbar tract is the UMN

Innervates CNs 7 & 12 contra laterally and unilaterally

CNs 5, 7, 11, &12 are innervated directly

CNs 3, 4, &6 don't have their nuclei directly innervated by the corticobulbar tract


Upper Motor Neurons

2 Main Types:
Corticospinal tract

Corticobulbar tract


Corticospinal Tract

One of 2 types of UMNs

Travels from the cortex, decussates, and synapses on LMNs in the spinal cord


Corticobulbar Tract

One of 2 Types of UMNs

Starts in the cortex and provides info to the CNs