Lec 8 Motor Systems

Question 1

3 motor pathways

Answer 1

bulbospinal, corticospinal, corticobulbar

Question 2

bulbospinal pathway is blank but the other two are blank

Answer 2

involuntary, voluntary

Question 3

motor neurons in cerebral cortex or brainstem and have axons that remain in CNS

Answer 3

upper motor neurons

Question 4

motor neurons with cell bodies in CNS but axons leave and synapse directly on muscle

Answer 4

lower motor neurons

Question 5

innervate extrafusal (contracting) muscle fibers. Use Acetylcholine as neurotransmitter released on the “end plate” (neuromuscular junction synapse), Acetylcholine activates Nicotinic Receptors (NR) can be blocked by curare.

Answer 5

alpha motor neurons

Question 6

innervate intrafusal muscle fibers (adjust sensitivity of Muscle Spindle receptors by regulating tension of muscle spindle).

Answer 6

gamma motor neurons

Question 7

spinal cord and motor apparatus can do these two things

Answer 7

reflexes, central pattern generating (like for walking)

Question 8

this coordinates reflexes of spinal cord

Answer 8

fasciculus proprius

Question 9

tectospinal tract, rubrospinal tract, vestibulospinal tract are all blank pathways

Answer 9

bulbospinal

Question 10

visual stimuli>optic nerve>S. colliculi> neck motoneurons

Answer 10

tectospinal

Question 11

Red nucleus>flexor motoneurons of distal arm, hand and foot gripping movement

Answer 11

rubrospinal tract

Question 12

vestibular nuclei>neck and axial motoneurons

Answer 12

vestibulospinal

Question 13

Reticular Formation:

1. Excites axial and leg extensor motoneurons
2. Inhibits spinal motoneurons

Answer 13

reticulospinal

Question 14

skilled and adaptive motor functions, complex behaviors…. voluntary movements… done by these tracts

Answer 14

corticobulbar, corticospinal

Question 15

Note corona radiate>internal capsule>Crus cerebri (cerebral pedunculi)> pyramidal tracks

Answer 15

corticospinal tract

Question 16

LMN lesion causes blank

Answer 16

paresis (flaccidity), ipsilateral

Question 17

UMN lesion causes blank

Answer 17

paresis (spastic), ipsilateral in spinal cord, contralateral if higher than spinal cord

Question 18

babinski sign is due to blank

Answer 18

umn lesion

Question 19

umn lesion is due to damage to the blank tract

Answer 19

lateral reticulospinal