Motor Systems Flashcards
voluntary muscle contraction path (neuron #1)
UMN
cell body in cerebral cortex (precentral gyrus - primary motor cortex)
cross midline @ pyramidal decussation in brain stem
voluntary muscle contraction path (neuron #2)
LMN
cell body in ventral horn (alpha)
voluntary muscle contractions path
UMN (in cerebral cortex)
cross midline @ pyramidal decussation in lateral corticospinal tract
LMN synapse on muscle
CST aka
pyramidal tract
voluntary muscle contractions path
UMN (in cerebral cortex)
cross midline @ pyramidal decussation in lateral corticospinal tract
LMN synapse on ipsi muscle
CST aka
pyramidal tract
muscle stretch reflex path
stretch affects muscle spindle
Ia fiber to DRG
synapse on LMN in ventral horn
affect skeletal muscle
muscle stretch reflex path
stretch affects muscle spindle
Ia fiber to DRG
synapse on LMN in ventral horn
affect skeletal muscle
UMN lesion
spinal cord: spastic weakness ipsi and below
medulla: spastic weakness contra and below
reflex: hypereflexivity
LMN lesion
flaccid weakness at level of lesion
LMN lesion
flaccid weakness at level of lesion
UMN and reflexes
UMN inhibit muslce stretch reflexes
UMN and reflexes
UMN inhibit muslce stretch reflexes
muscle stretch reflex
patellar tendon
muscle spindle to Ia to DRG to ventral root
contract quads
inhibit hams
inverse myotatic reflex
excessive force
golgi tendon organ to Ib to DRG to ventral root
inverse myotatic reflex
excessive force
golgi tendon organ to Ib to DRG to ventral root
LMN makes muscle relax
UMN and reflexes
UMN inhibit muslce stretch reflexes
inverse myotatic reflexes –> clasp knife reflex
clinical grading of muscle strength
0/5 = can't move 5/5 = normal strength
clinical grading of muscle stretch reflexes
0 = no reflex 2+ = normal 4 = hyperactive stretch reflexes w/ clonus
UMN lesion sx
spastic weakness contra or ipsi and below lesion
hyperreflexia (clonus)
babinski sign
up muscle tone
LMN lesion sx
flaccid paralysis @ level of lesion areflexia (or hypo) no babinski down muscle tone fasciculations and atrophy (severe)
babinski sign
toes go up when touched along bottom of foot
babinski sign
toes go up when touched along bottom of foot
UMN lesion contra vs ipsi
in brain = contra (cross at pyramidal decassation)
spinal cord = ipsilateral
