Chapter 17

Question 1

UMNS are located in the

Answer 1

brainstem or cerebral cortex and send descending axons to synapse with the local circuit neurons or rarely with the lower motor neurons.

Question 2

Axons of UMNs in brainstem course through

Answer 2

the anterior medial white matter of spinal cord and terminate on medial cell groups in both sides of the spinal cord

Question 3

Axons of UMNs in motor cortex course through

Answer 3

the lateral white matter of spinal cord

Question 4

Axons of UMN in motor cortex terminate on the

Answer 4

contralateral side of the spinal cord and mediate the expression of skilled voluntary movements of distal extremities

Question 5

Axons of UMNs from brainstem terminate on

Answer 5

both side of the spinal cord and govern posture and balance mechanisms of axial muscles.

Question 6

Brainstem upper motor neurons

Answer 6

medial lower motor neurons (both sides) > axial muscles for posture control

Question 7

cortical upper motor neurons

Answer 7

lateral lower motor neurons (contralateral side) > distal muscles for skilled movement

Question 8

Motor cortex contains two parts

Answer 8

primary motor cortex and premotor cortex

Question 9

Corticospinal tract:

Answer 9

the axons of the upper motor neurons in the motor cortex descend and terminate in the contralateral spinal cord.

Question 10

Purposeful movements are mapped in the

Answer 10

primary motor cortex

Question 11

Neurons in the primary motor cortex encode intentions for

Answer 11

movements in central personal space

Question 12

Population coding

Answer 12

the commands to perform precise movement patterns are encoded by the concurrent discharges of a large population of UMNs

Question 13

premotor cortex

Answer 13

four interconnected frontal lobe areas that lie anterior to the primary motor cortex

Question 14

UMNs in the lateral premotor cortex encode

Answer 14

intentions for movements that are oriented toward extra personal space.

Question 15

Mirror motor neurons

Answer 15

a subset of UMNs in premotor cortex fire in response to not only preparation of a particular movement, but also to observation of the particular movement being performed by others.

Question 16

Primary motor cortex encodes (5 things)

Answer 16

1. movements for muscle contraction
2. intentions for movements in central personal space
3. these movements are purposeful/pre-programmed movements
4. population coding

Question 17

3 functions of UMNs in the brainstem:

Answer 17

1. vestibular complex
2. reticular formation
3. superior colliculus

Question 18

Descending projections from VCR from:

Answer 18

semicircular canals > UMNs in medial vestibular nucleus > LMNs in cervical spinal cord > neck muscles > regulates head position

Question 19

Descending projections in VSR

Answer 19

otolith organs > UMNs in lateral vestibular nucleus > LMNs in thoracic and lumbar spinal cord > body muscles > regulates posture

Question 20

Descending projections from reticular formation (corticoreticular pathway)

Answer 20

UMNs in premotor cortex > UMNs in reticular formation > LMNs in thoracic/lumbar spinal cord > body muscles > regulates posture

Question 21

Vestibular nuclei and reticular formation both provide

Answer 21

information to the spinal cord for posture maintenance.

Question 22

UMNs in vestibular nuclei ensure a

Answer 22

rapid compensatory feedback reflex response to any existing postural instability.

Question 23

UMNs in reticular formation initiate

Answer 23

feedforward voluntary adjustments that stabilize posture during ongoing movements (predicts, anticipates, the posture instability to adjust posture)

Question 24

Midterm Question: Application question on whether or not it is a vestibular nuclei or reticular formation.

Question 25

Superior colliculus

Answer 25

control the orienting head and eye movement

Question 26

Cortico-collicular pathway

Answer 26

sensory inputs from visual cortex > UMNs in cortex > UMNs in superior colliculus > LMNs in cervical spinal cord > orienting head and eye movements (saccade)