Lecture 20 (4/16) Flashcards
Damage to Motor Neurons
Damage to the Lower Motor Neurons
Causes:
- Paralysis or diminution of movement
- Decrease in muscle tone - hypotonia
- Loss of tendon reflexes
- Atrophy
- Fibrillations (tremors) and/or fasciculations (spontaneous activity of muscle fibers)
Damage to the Upper Motor Neurons
Causes:
- Paralysis, diminution of movement
- Spasticity - increased muscle tone
- Overactive tendon reflexes
- Atrophy is rare in UMNs and there are no fasciculations
- 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
