Motor and Sensory Flashcards
M1
Motor cortex
Precentral gyrus
Homonculus
Corticospinal tract
Motor system
Upper motor neuron (cortex) to midbrain, to medulla (cross), to spinal cord lower motor neuron
Damage to corticospinal tract
Loss of strength Decorticate thumb Babinski reflex re-emerges legs circumduct upper body flexion lower body extension brisk increased reflexes on weak side
Damage to upper motor neuron
Forehead spared
Damage to lower motor neuron
Forehead weak
Spinal reflex arc
stimulus, stretch receptor, sensory neuron, interneuron, motorneuron, reflex
Babinski
upon stroking, toes spread out
normal in baby, re-emerges in corticospinal damage
Lesion in M1
distal weakness (not proximal)
Check for distal strength
arms out, check hand pronation
hands out and fingers spread
push on index and pinky
observe if fingers kept apart
Check speed/movement decrease
patient taps thumbs and index fingers
possible but slow
S1
Somatosensory cortex
postcentral gyrus
Homonculus
Cerebellum
feedback control
responsible for rhythm, rate, direction
Check coordination/gait
finger to nose/heel to shin testing simple and complex finger movements three step motor movements heel to toe walking Romberg test
Nigrostriatal Pathway
Basal ganglia
substantia nigra gives dopamine to caudate/putamen
Parkinson’s causes
Decrease dopamine (less than 25%)
