16.4

Question 1

lower motor neurons

Answer 1

all excitatory & inhibitory signals that control movement converge on these motor neurons that extend out of the brainstem & spinal cord to innervate skeletal muscles in the body

Question 2

Where are the cell bodies located in lower motor neurons?

Answer 2

in the lower parts of the CNS ( brainstem and spinal cord)

Question 3

from the brainstem, axons of LMNs extend through _____ to innervate skeletal muscles of the face & head

Answer 3

cranial nerves

Question 4

from the spinal cord axons of LMNs extend through ____ to innervate skeletal muscles of the limbs & trunk

Answer 4

spinal nerves

Question 5

why are the LMNs called the final common pathway?

Answer 5

Only LMNs provide output from the CNS to skeletal muscle fibers

Question 6

input arrives at lower motor neurons from nearby interneurons called

Answer 6

local circuit neurons

Question 7

where are local circuit neurons located>

Answer 7

close to the lower motor neurone cell bodies in the brainstem and spinal cord

Question 8

what do local circuit neurons function

Answer 8

help coordinate rhythmic activity in specific muscle groups such as alternating flexion and extension of the lower limbs during walking

Question 9

both local circuit neurons & lower motor neurons receive input from?

Answer 9

Upper motor neurons

Question 10

Upper motor neurons are located where? 2 places

Answer 10

cerebral cortex - planning & execution of voluntary movements of body
motor centres of brainstem - help regulate posture, balance, muscle tone & reflective movements of the head and trunk

Question 11

Which neurons assist with movement by providing input to upper motor neurons?

Answer 11

Basal nuclei neurons

Question 12

Neural circuits interconnect the basal nuclei with motor areas of the cerebral cortex (via the thalamus) and brainstem. What do these circuits help with?

Answer 12

Initiating and terminating movements, suppress unwanted movements, and establish a normal level of muscle tone

Question 13

Cerebellar neurons?

Answer 13

also aid movement by controlling the activity of upper motor neurons

Question 14

neural cicuits interconnect the cerebellum with motor areas of the cerebral cortex (via the thalamus) and brainstem. A prime function of the cerebellum is to

Answer 14

monitor differences between intended movements & movements performed. Then it issues commands to UMN to reduce errors in movement

Question 15

control of body movements involves motor pathways that begin in motor areas of the cerebral cortex. 2 areas are the?

Answer 15

Premotor area (area 6 in frontal lobe)
primary motor are (area 4 in the precentral gyrus of frontal lobe)

Question 16

The role of the premotor area in body movements? steps

Answer 16

1. desire to move a part of body generated in one or more cortical association areas (such as prefrontal cortex, somatosensory association are, auditory association area or visual association area)
2. this info sent to basal nuclei which processes the info & sends to thalamus and then to premotor area where a motor plan is developed
3. the plan identifies which muscle should contract, how much they need to contract and in which order.
4. from the premotor are the plan is transmitted to the primary motor are for execution

Question 17

which area is the major control region for the execution of voluntary movements?

Answer 17

the primary motor area

Question 18

electrical stimulation of any point in the primary motor area causes>

Answer 18

contraction of specific muscles on opposite side of the body

Question 19

motor homunculus

Answer 19

distorted muscle map of the body which is present in the primary motor area (each point within the area controls muscle fibres in different parts of the body)

Question 20

which pathway provides input to the lower motor neurons via axons that extend directly from the cerebral cortex

Answer 20

direct motor pathways

Question 21

which pathway provides input to the lower motor neurons from motor centres in the brainstem?

Answer 21

indirect motor pathways

Question 22

action potentials for voluntary movements propagate from the cerebral cortex to lower motor neurons via ?

Answer 22

direct motor pathways

Question 23

the direct motor pathways (also known as pyramidal pathways) consist of axons that descend from>

Answer 23

pyramidal cells of the primary motor area and premotor area

Question 24

the main output cells of the cerebral cortex?

Answer 24

pyramidal cells (upper motor neurons that have pyramid shaped cell bodies)

Question 25

direct motor pathways (2 types)

Answer 25

corticospinal pathways and corticobulbar pathway

Question 26

which pathway conduct impulses for the control of muscles of the limbs and the trunk

Answer 26

corticospinal pathways

Question 27

axons of upper motor neurons in the cerebral cortex form the?

Answer 27

corticospinal tracts –> which descend through the internal capsule of the cerebrum & the cerebral peddle of the midbrain

Question 28

which corticospinal tract conveys nerve impulses from motor cortex to skeletal muscles on opposite side of body for precise voluntary movements of distal parts of limbs (ex buttoning a shirt)

Answer 28

lateral corticospinal tract

Question 29

corticospinal axons that decussate in the medulla form the

Answer 29

lateral corticospinal tract in the lateral white column of the spinal cord

Question 30

corticospinal axons that do not decussate in the medulla form the ___

Answer 30

anterior corticospinal tract in the anterior white column of the spinal cord

Question 31

conveys nerve impulses from the motor cortex to skeletal muscles on opposite sides of the body for movements of trunk and proximal part of limbs

Answer 31

anterior corticospinal tracts

Question 32

corticobulbar pathway

Answer 32

conducts impulses for the control of skeletal muscles in the head

Question 33

axons of UMNs descend from the cortex into brainstem where some decussate & others do not. They provide input to lower motor neurons in the nuclei of the oculomotor (III), trochlear (IV), trigeminal (V), abducens (VI), facial (VII), glossopharyngeal (IX), vagus (X), accessory (XI), and hypoglassal (XII) nerves. which control?

Answer 33

voluntary movements of the eyes, tongue and neck, chewing, facial expression, and speech

Question 34

the brainstem is another region important to motor control. It contains 4 major centres that help regulate body movements which are>

Answer 34

1. vestibular nuclei - in the medulla & pons
2. reticular formation - located throughout brainstem
3. superior colliculus - in the midbrain
4. red nucleus - in midbrain

Question 35

The brainstem motor centres give rise too?

Answer 35

indirect motor pathways (also known as extrapyramidal pathways)
include all somatic motor tracts other than the corticospinal & corticobulbar tracts

Question 36

the indirect motor pathways convey action potentials from the brainstem to cause what kind of movements

Answer 36

involvuntary movements that regulate posture, balance, muscle tone & reflective movements of the head and trunk

Question 37

the vestibular nuclei play an important role in regulation of?

Answer 37

posture

Question 38

Where do vestibular nuclei receive neural input from?

Answer 38

vestibulocochlear (VIII) nerve regarding the state of equilibrium of the body and neural input from the cerebellum

Question 39

in response to the input, the vestibular nuclei generate action potentials along axons of the ______ tract which conveys signals to ____ muscles of the trunk and _____ parts of the limbs

Answer 39

vestibulospinal tract, skeletal, proximal

Question 40

rubrospinal pathway

Answer 40

conveys nerve impulses from red nucleus (which receives input from the cerebral cortex and cerebellum) to contralateral skeletal muscles that govern precise voluntary movements of distal parts of upper limbs

Question 41

which pathway Conveys nerve impulses from superior colliculus to contralateral skeletal muscles that reflexively move head, eyes, and trunk in response to visual or auditory stimuli.

Answer 41

tectospinal pathway

Question 42

which pathway Conveys nerve impulses from vestibular nucleus (which receives input about head movements from inner ear) to ipsilateral skeletal muscles of trunk and proximal parts of limbs for maintaining posture and balance in response to head movements.

Answer 42

vestibulospinal pathway

Question 43

which pathway Conveys nerve impulses from reticular formation to ipsilateral skeletal muscles of trunk and proximal parts of limbs for maintaining posture and regulating muscle tone in response to ongoing body movements.

Answer 43

lateral & medial reticulospinal pathways

Question 44

Basal nuclei functions

Answer 44

initiation of movements
suppression of unwanted movements
regulation of muscle tone
regulation of non motor processes