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Flashcards in Motor Systems Deck (24)
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1

voluntary muscle contraction path (neuron #1)

UMN
cell body in cerebral cortex (precentral gyrus - primary motor cortex)
cross midline @ pyramidal decussation in brain stem

2

voluntary muscle contraction path (neuron #2)

LMN
cell body in ventral horn (alpha)

3

voluntary muscle contractions path

UMN (in cerebral cortex)
cross midline @ pyramidal decussation in lateral corticospinal tract
LMN synapse on muscle

4

CST aka

pyramidal tract

5

voluntary muscle contractions path

UMN (in cerebral cortex)
cross midline @ pyramidal decussation in lateral corticospinal tract
LMN synapse on ipsi muscle

6

CST aka

pyramidal tract

7

muscle stretch reflex path

stretch affects muscle spindle
Ia fiber to DRG
synapse on LMN in ventral horn
affect skeletal muscle

8

muscle stretch reflex path

stretch affects muscle spindle
Ia fiber to DRG
synapse on LMN in ventral horn
affect skeletal muscle

9

UMN lesion

spinal cord: spastic weakness ipsi and below
medulla: spastic weakness contra and below
reflex: hypereflexivity

10

LMN lesion

flaccid weakness at level of lesion

11

LMN lesion

flaccid weakness at level of lesion

12

UMN and reflexes

UMN inhibit muslce stretch reflexes

13

UMN and reflexes

UMN inhibit muslce stretch reflexes

14

muscle stretch reflex

patellar tendon
muscle spindle to Ia to DRG to ventral root
contract quads
inhibit hams

15

inverse myotatic reflex

excessive force
golgi tendon organ to Ib to DRG to ventral root

16

inverse myotatic reflex

excessive force
golgi tendon organ to Ib to DRG to ventral root
LMN makes muscle relax

17

UMN and reflexes

UMN inhibit muslce stretch reflexes
inverse myotatic reflexes --> clasp knife reflex

18

clinical grading of muscle strength

0/5 = can't move
5/5 = normal strength

19

clinical grading of muscle stretch reflexes

0 = no reflex
2+ = normal
4 = hyperactive stretch reflexes w/ clonus

20

UMN lesion sx

spastic weakness contra or ipsi and below lesion
hyperreflexia (clonus)
babinski sign
up muscle tone

21

LMN lesion sx

flaccid paralysis @ level of lesion
areflexia (or hypo)
no babinski
down muscle tone
fasciculations and atrophy (severe)

22

babinski sign

toes go up when touched along bottom of foot

23

babinski sign

toes go up when touched along bottom of foot

24

UMN lesion contra vs ipsi

in brain = contra (cross at pyramidal decassation)
spinal cord = ipsilateral