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neuro lec 4


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lower motorneurons
connect directly or muscle fiber
upper motorneurons
descending axons from cortex and brainstem
basal ganglia (in terms of neuromuscular)
modlualtes motor cortex output
cerebellum (in terms of neuromuscular)
modlualtes brainstem output
alpha motorneurons
lower, get extrafusal muscle fibers
gamma motor neurons
- lower, get intrafusal motorneurons, smaller than alpha
- helps take up slack caused by contraction of extrafusal
IA afferant fibers
largest and fastest, excitatory in muscle stretched and inhibitory interneruon in antogonistic muscle
IB afferant fibers
large and fast, excitatory in antogonistic muscle and inhibitory interneruon in muscle stretched
motor cortex in descending pathways
plan, initiate and direct voluntary movement - axons are the longes in CNS and run dorsolateral in spinal cord
brainstem in descending pathways
posture and balance - neurons arise form vestibular and reticular nuclei - axons run in medial ventral spinal cord to get posture muscles
cerebellum in descending pathways
sensory motor coordination - influences output from motor cortex and brainstem
basal ganglia in descending pathways
initation of movement - influences output from motor cortex and brainstem
vestibular pathway
in brainstem - maintains balance via inner ear inputs
reticular pathway
in brainstem - maitains balance from input from brainstem or cortical motor centers to maintain equilibrium during movement
ventral medulla damage
only place where corticospinal tract is isolated - have difficulty with fine finger movements
dorsolateral funiculus lesion
can fractionate movement - slow, less accureate movement
corticospinal tract lesion
- initially can fractionate movement - slow, less accureate movement
- then only the fingers can't fractionate movement
premotor cortex damage
- linked to basal ganglia
- aproxia - where you can't develop strategies for complex movements (brushing teeth)
premotor cortex lateral neurons
- fire in perparation for movments elicited by external stimuli
- if damaged, cant decide what movement to make
premotor cortex medial neurons
- fire in perparation for volatile movments elicited by internal stimuli - active when doing complex thins by memory
Myasthenia garvis associated w/
thyroid disease, amenia, DMI, rhemetoid arthitis, lupus, increase MHC markers (thymectory helps)
Myasthenia garvis ACh
- the ACh relased is normal, but EPP is smaller
- as # decreases w/ RNS, EPP's fall bacuase they cant reach the threshold
Myasthenia garvis diagnosis
- give endrophonium slows ACh hydrolysis - will help those w/ MG so used to diagnose
- test RNS for ACh Ab levels
Myasthenia garvis treatment that helps NT release
pyridostigmine, neostigmine
Myasthenia garvis treatment that helps immune suppression
steriods, cyclosporine, mycophenolate mofetil, azathioprine, inhibit IL-2 to increase CD8 suppression and decrease CD4 helper

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