Descending Motor Systems Flashcards
Where are the lower motor neurons located?
In the lamina 8 of the spinal cord, ventral (anterior) gray matter
Where is the primary motor cortex located?
pre-central gyrus
What happens when the pre-motor cortex is damaged?
apraxias
What are the two effects that the UMN has on LMN?
- increases firing rate during voluntary movements
- inhibits afferent input to LMN through inhibitory interneurons
Where does the vestibulospinal tract receive input from?
NOT the cortex, the vestibular ganglia
what is the lateral vestibulospinal tract responsible for?
anti-gravity response
What is the medial vestibulospinal tract responsible for?
ipsilateral/contralateral and mediates other responses to vestibular input; cross at the medullary-pontine junction
Where is the “vestibule area”?
floor of the fourth ventricle
What symptoms does brainstem disease produce?
life-threatening coma and alterations to heart rate and breathing
What are the 7 things that can cause weakness?
- muscular pathology (muscular dystrophy)
- neuromuscular junction
- nerve pathology (compression)
- lower motor neuron pathology
- corticospinal tract pathology (stroke of the internal capsule)
- primary motor cortex pathology
- premotor correct pathology
Weakness, hyper-flexia, hypertonia, spasticity, disuse atrophy, hyper-reflexia are all signs of a lesion where?
Upper motor
weakness, hyporeflexia, hypotonia, “marked” atrophy, fasciulations of muscles are signs of a lesion where?
lower motor lesion
What tract inhibits reflexes
corticospinal tract
Are reflexes exaggerated or diminished if the corticospinal tract is damaged?
exaggerated
skilled movements of the extremities
lateral corticospinal tract
