Motor Systems

Question 1

voluntary muscle contraction path (neuron #1)

Answer 1

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

Question 2

voluntary muscle contraction path (neuron #2)

Answer 2

LMN

cell body in ventral horn (alpha)

Question 3

voluntary muscle contractions path

Answer 3

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

Question 4

CST aka

Answer 4

pyramidal tract

Question 5

voluntary muscle contractions path

Answer 5

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

Question 6

CST aka

Answer 6

pyramidal tract

Question 7

muscle stretch reflex path

Answer 7

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

Question 8

muscle stretch reflex path

Answer 8

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

Question 9

UMN lesion

Answer 9

spinal cord: spastic weakness ipsi and below

medulla: spastic weakness contra and below
reflex: hypereflexivity

Question 10

LMN lesion

Answer 10

flaccid weakness at level of lesion

Question 11

LMN lesion

Answer 11

flaccid weakness at level of lesion

Question 12

UMN and reflexes

Answer 12

UMN inhibit muslce stretch reflexes

Question 13

UMN and reflexes

Answer 13

UMN inhibit muslce stretch reflexes

Question 14

muscle stretch reflex

Answer 14

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

Question 15

inverse myotatic reflex

Answer 15

excessive force

golgi tendon organ to Ib to DRG to ventral root

Question 16

inverse myotatic reflex

Answer 16

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

Question 17

UMN and reflexes

Answer 17

UMN inhibit muslce stretch reflexes

inverse myotatic reflexes –> clasp knife reflex

Question 18

clinical grading of muscle strength

Answer 18

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

Question 19

clinical grading of muscle stretch reflexes

Answer 19

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

Question 20

UMN lesion sx

Answer 20

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

Question 21

LMN lesion sx

Answer 21

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

Question 22

babinski sign

Answer 22

toes go up when touched along bottom of foot

Question 23

babinski sign

Answer 23

toes go up when touched along bottom of foot

Question 24

UMN lesion contra vs ipsi

Answer 24

in brain = contra (cross at pyramidal decassation)

spinal cord = ipsilateral