Chapter 15 part 3

Question 1

somatic motor pathways always involve at least _____motor neurons:

Answer 1

2:
upper motor neuron
lower motor neuron

Question 2

where is the nucleus of the upper motor neuron and the lower motor neuron

Answer 2

nucleus of upper motor neuron lies in the CNS processing center

nucleus of lower motor neuron lies in a nucleus of the brain stem or spinal cord

Question 3

explain how a single motor unit in a skeletal muscle is innervated

Answer 3

the upper motor neuron synapses on the lower motor neuron, which then innervates a single motor unit in the skeletal muscle

Question 4

do the axons of the upper and lower motor neuron extend outside of the CNS?

Answer 4

NO
only the axon of the lower motor neuron does

Question 5

what happens if a lower motor neuron is destroyed or damaged?

Answer 5

eliminates voluntary and reflex control over the innervated motor unit

Question 6

activity in the upper motor neuron may ___ or ____ the lower motor neuron

Answer 6

facilitate or inhibit

Question 7

conscious and subconscious motor commands control skeletal muscles by traveling over three integrated motor pathways.
what are they?

Answer 7

-the corticospinal pathway
-the medial pathway
-the lateral pathway

Question 8

the output of these 3 motor centers stimulates or inhibits the activity of either _____ or _____

Answer 8

motor nuclei or the primary motor cortex

Question 9

the corticospinal pathway provides…….

Answer 9

voluntary control over skeletal muscles

Question 10

the corticospinal pathway is sometimes called the ____ system

Answer 10

pyramidal

Question 11

what are the upper motor neurons of the corticospinal pathway?

Answer 11

pyramidal cells

Question 12

explain how the corticospinal pathway is both direct and indirect

Answer 12

direct because the upper motor neurons synapse directly on the lower motor neurons that innervat skeletal muscle

indirect because the corticospinal pathway innervates centeres of the medial and lateral pathways

Question 13

the corticospinal pathway contains _____ pairs of descending tracts:

Answer 13

-corticobulbar tract
-lateral corticospinal tract
-anterior corticospinal tract

Question 14

the corticobulbar tract provides conscious control over..

Answer 14

skeletal muscles that move the jaw, phase, and some muscles of neck and pharynx (cranial nerves III-vii, ix, xi, xII)

Question 15

what is a motor homunculus?

Answer 15

representation of the body’s motor functions in the brain.
shows which areas of the brain control different parts of the body

Question 16

true or false

motor control is integrated at all levels through extensive feedback loops and interconnections

Answer 16

true

Question 17

the components of the medial pathway help to control…

Answer 17

gross movements of the trunk and proximal limb muscles

Question 18

the components of the lateral pathway help to control…

Answer 18

the distal limb muscles that perform more precise movements

Question 19

which pathways innervate the SAME lower motor neurons?

Answer 19

the medial and lateral pathways innervate the same motor neurons as the corticospinal pathway

Question 20

the medial pathway is primarily concerned with control of…

Answer 20

muscle tone and gross movements of the neck, trunk, and proximal limb muscles

Question 21

the upper motor neurons of the _____ pathway lie within the red nuclei of the _________

Answer 21

lateral pathway, midbrain

Question 22

the _ and ______ are responsible for coordination and feedback control over muscle contractions

Answer 22

BASAL NUCLEI AND CEREBELLUM

Question 23

the basal nuclei provide the _ patterns of movement involved in voluntary motor activities

Answer 23

background — ie: the background position of the trunk or limbs, or direct rhythmic cycles of movement as in walking or running

Question 24

explain how the basal nuclei work to perform their function

Answer 24

they do NOT exert direct control over the lower motor nuclei.
instead, they adjust the activities of the upper motor neurons based on input from all portions of the cerebral cortex, as well as the substantia nigra