Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A&P module 4 CNS > 4.3 Physiology of Somatic Motor System > Flashcards

4.3 Physiology of Somatic Motor System Flashcards

1
Q

Functions of somatic motor system

4

A

General functions of the somatic motor system

  1. Skilled, voluntary skeletal muscle activity
  2. Subconscious adjustment of posture
  3. Subconscious coordination of different muscle groups to make movements smooth and precise
  4. Subconscious protective reflexes -
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

___________- a.k.a. ventral anterior horn cell, α-motor neuron, efferent neuron to skeletal muscle, or somatic efferent neuron

A

lower motor neuron - a.k.a. ventral anterior horn cell, α-motor neuron, efferent neuron to skeletal muscle, or somatic efferent neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

“final common pathway” is?

through?

A

The lower motor neuron through

spinal and cranial nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q 
Higher centers that regulate lower motor neuron-
c
p v r 
B
C
SR
A

1-cerberal cortical motor areas/cerebral cortex/precentral gyrus
…corticospinal/pyramidal tract, corticobulbar/corticonuclear tract

2-Extra pyramidal tract..Vestibulospinal tract and Reticulospinal tract

3-Basal nuclei and accessories

i. Basal nuclei (caudate nucleus, globus pallidus, putamen)
ii. Substantia nigra (a cluster of neurons in the midbrain)
iii. Subthalamic nucleus

  1. cerebellum
  2. spinal reflex arcs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the three descending motor pathways
c
r
v

A

corticospinal tracts
Reticulospinal tract
Vestibulospinal tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

neither the ____ nor the ____ have any direct connections with the lower motor neurons

A

basal nuclei, cerebellum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Neurons from many areas of the CNS can affect somatic motor function but they all eventually pass information to the _____ located in the anterior horns of the spinal cord or similar areas in the brain stem

A

lower motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

work by influencing the function of the descending tract above
2

A

basal nuclei, cerebellum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  • A lower motor neuron must integrate many input signals ______ arriving continually from several different areas of the nervous system
A

(IPSPs or EPSPs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

most descending fibers that control motor activity synapse on ____ vs. lower motor neurons

A

interneurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

(IPSPs or EPSPs) integrate

A

at the axon hillock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The lower motor neurons are called the final pathway because

A

only lower motor neurons actually stimulate skeletal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The corticospinal tract originates from the following areas:
1.
2.
3.

A
  1. The motor cortex (area 4)
  2. The supplemental and pre-motor cortex (area 6)
  3. The parietal cortex (areas 3,1,2)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  • The motor cortex is connected to the final common pathway via _____, ______,and _____
A

the lateral and ventral corticospinal tract, corticobulbar upper motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

This area is chiefly concerned with skilled, voluntary movements of the hands and face ( as seen on the motor homunculus)

A

the lateral and ventral corticospinal tract, corticobulbar upper motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Most neurons emanating from the motor and premotor cortical areas synapse on____, which in turn synapse on the lower motor neurons.

A

interneurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Most of these interneurons are ____ and prevent lower motor neurons from over-discharging when responding to reflex stimulation

A

inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Injury to upper motor neurons can abolish or lessen the output of these inhibitory interneurons to lower motor neurons; the result could be _____

A

hyperreflexia or increased muscle tone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The motor system relies on sensory feedback for control of voluntary movements. This feedback comes from:
4
senses

A
  1. Sensory receptors in muscles and joints (proprioceptors)
  2. Visual input
  3. Vestibular input from the internal ear (equilibrium)
  4. Pressure and touch receptors in the body surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Effects of injury to corticobulbar or corticospinal tract upper motor neurons; most commonly caused by stroke would include:

A
  1. Spasticity (involuntary movements) and exaggerated reflexes (hyperreflexia)
  2. Loss of voluntary movement
  3. Profound weakness or paralysis affecting the face (corticobulbar), trunk (ventral corticospinal) and extremities (lateral corticospinal)
  4. Depressed or absent superficial reflexes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

These reflexes are elicited by cutaneous afferents, require intact upper motor neurons and are polysynaptic.

A

superficial reflexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q
  • These reflexes are typically elicited by the muscle receptors (e.g., muscle spindle), do not require an upper motor neuron but only a lower motor neuro and are typically monosynaptic.
A

Deep reflexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Big toe goes up and toes fan apart when the sole of the foot is stroked from heel-to-toe (thus, a superficial reflex)

A

Babinski sign
Normally seen in infants but not in adults
Would Indicate damage to an upper motor neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The main subcortical Motor Area:

A

Basal nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

The basal nuclei do not have any direct influence on the final common pathway. It is part of a ____ that considers various courses of action before the final movement plan is sent down the corticospinal tracts

A

“movement planning circuit”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

In essence, the basal ganglia are part of a _____

A

corticocortical loop that is superimposed on the corticospinal tracts - The circuit starts as output from the motor cortex is sent to the basal nuclei. The basal nuclei consider various courses of action and then select the best one. The best course of action is then sent to the thalamus and back to the motor cortex. The best solution can then be sent down the corticospinal tract.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Anatomy of the basal nuclei: 3 main parts

A

(a) Caudate nucleus
(b) Putamen
(c) Globus pallidus (externa and interna) -

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Associated areas of the basal nuclei: 2 parts

A

(a) Substantia nigra (Pars compacta and Para reticularis)

(b) Subthalamic nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Overall role of the basal nuclei in movement is to _____ or______.

A

reinforce, suppress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Involved in planning and programming voluntary movement; in essence, the basal nuclei ____ desired motor activity and ____ unwanted motor activity

A

reinforce, suppress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q
  • together these two component form the striatum:
A

the caudate nucleus and putamen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Describe motor neural circuitry (a looping circuit)

A 
short answer 
Motor cortex to Basal nuclei 
basal nuclei to thalamus 
Thalamus to motor cortex 
motor cortex to lower motor neurons

Describe motor neural circuitry (a looping circuit)
Input from the Motor areas of the cerebral cortex and the substantia nigra pars compacta (midbrain), this input enters the basal nuclei (in the caudate nucleus and putamen) and then follows the direct or indirect pathway. Output from the basal nuclei (either from the Globus pallidus pars interna or the Substantia nigra pars reticularis) is directed through the thalamus back to the cortex, completing the looping circuit -

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

There are two major pathways within the basal nuclei and associated nuclei

A

(a) Direct pathway: facilitates movement

(b) Indirect pathway: inhibits movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

For normal movement there should be a balance in the activities of the ____and ______pathways

A

direct and indirect pathways

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

The ____ modulates the activities of these two pathways via dopaminergic neurons.

A

substantia nigra pars compacta

36
Q

signals through Gs; thus, it is excitatory and facilitates motor activity

A

D1 receptor-

37
Q

signals through Gi; thus, it is inhibitory and facilitates motor activity through disinhibition -

A

D2 receptors

38
Q

Postsynaptic neurons of the direct pathway are located in the striatum and contain the ____ receptor

A

D1

39
Q

(b) Postsynaptic neurons of the indirect pathway are also located in the striatum and contain ____.

A

D2

40
Q

Disorders of the basal nuclei:

A

Parkinson’s disease

Huntington’s disease

41
Q

Dopaminergic neurons connecting the substantia nigra pars compacta and the striatum die, resulting in underactivity in the direct pathway and overactivity in the indirect pathway

A

Parkinson’s disease -

42
Q

The net result is decreased stimulation of the motor cortex and thus one of the following phenotypes:

(a) Hypokinesia: scarcity of spontaneous movement
(b) Akinesia: lack of movement
(c) Bradykinesia: Slowness of movement
(d) Hypertonia (rigidity)

A

Parkinson’s disease

43
Q

An inheritable autosomal dominant disorder in which striatal neurons die

A

Huntington’s disease -

44
Q

Neurons of the indirect pathway are preferentially lost and in the end this causes chorea (i.e., hyperkinesias: rapid, random, jerky movements of the face and extremities)

A

Huntington’s disease -

45
Q

Basal ganglion disorders don’t cause ____; instead they affect quality of movement (i.e., cause excessive suppression of movement [hypo- or akinesia] or extraneous movement [hyperkinesia])

A

paralysis -

46
Q

Descending spinal pathways other than the corticospinal tracts:

A

Reticulospinal tract and Vestibulospinal tract

47
Q

Originates from several nuclei located in the reticular formation of the pons and medulla (brain stem)

A

Reticulospinal tract -

48
Q

The reticular nuclei receive input from the ____, ____ and ____

A

The reticular nuclei receive input from the ____, ____ and ____
basal nuclei, cerebellum, and vestibular nuclei

49
Q

Reticulospinal neurons descend in the spinal cord and terminate on ____

A

lower motor neurons

50
Q
  • The reticular nuclei subconsciously regulates trunk muscle activity to _____ and muscle tone; this positions and stabilizes the trunk to facilitate skilled movements
A

maintain body posture

51
Q

The reticulospinal tract also has an UNRELATED autonomic nervous system function—transmitting action potentials from the hypothalamus to preganglionic sympathetic neurons in the ____ of the spinal cord; keep this function separate from the somatic motor system

A

intermediolateral horns

52
Q

Originates from a vestibular nucleus located in the reticular formation of the medulla

A

Vestibulospinal tract

53
Q

The vestibular nucleus receives input from ____ and also from the ____

A

equilibrium receptors in the inner ear, cerebellum

54
Q

Vestibulospinal neurons descend in the spinal cord and terminate on ____

A

lower motor neurons

55
Q

Injury to these tracts will obviously impair muscle tone and equilibrium - The vestibular nucleus unconsciously regulates skeletal muscle activity chiefly in the trunk to ____

A

maintain body equilibrium or balance

56
Q

Like the basal nuclei, has no direct control over the final common pathway but instead serves to adjust the output of the motor cortex and the vestibulospinal and reticulospinal tracts of the brain stem

A

the cerebellum

57
Q

The motor cortex initiates movements while the cerebellum is responsible for:

A

a. Posture & balance maintenance

b. Smoothes and coordinates ongoing movements

58
Q

the two cerebellar hemispheres are connected with the rest of the CNS by the ____, _____, and______

A

superior, middle, and inferior cerebellar peduncles

59
Q
  1. Proprioceptive information (position sense)from___and ____ receptors located in the ____, _____, ____, and _____via the ______ and _______ cerebellar peduncles
A
  1. Proprioceptive information (position sense)from muscle and joint receptors located in the trunk, limbs, head, and neck via the superior and inferior cerebellar peduncles
60
Q
  1. Visual information
A

via the superior cerebellar peduncle

61
Q

Vestibular information

A

from receptors in the inner ear via the inferior cerebellar peduncle

62
Q
  1. Commands from the motor areas of the cerebral cortex Input received and integrated by the cerebellum: comes from___via____
A
  1. Commands from the motor areas of the cerebral cortex
    Input received and integrated by the cerebellum: comes from___via____

via the middle cerebellar peduncle

63
Q
  • Output from the cerebellum goes to:
A
  1. Vestibular nuclei and reticular nuclei of the brain stem

2. To the motor cortex -

64
Q

Vestibular nuclei and reticular nuclei of the brain stem influences the activity of the _____ to adjust posture and muscle tone in trunk, neck and proximal limb muscles to maintain equilibrium during movement

A

vestibulospinal and reticulospinal tracts

65
Q

The motor cortex neurons extend from the lateral portions of the cerebellar hemispheres to the thalamus

A

premotor and primary motor areas of the cerebral cortex

66
Q

From the thalamus, cerebellar output is relayed to the ____

A

premotor and primary motor areas of the cerebral cortex

67
Q

Uses sensory information to adjust the activity of the corticospinal tract upper motor neurons
(optimizes performance of movements and controls the rate, range, force, and direction of movement)
Coordinates reciprocal innervation of agonist and antagonist muscle groups -

A

Functions of the cerebellum:

68
Q

Since the cerebellum does not initiate movements, no ___ results from cerebellar injury

A

Paralysis

69
Q

Cerebellar lesions generally produce ____ as well as diminishing the quality of skilled movements

A

disorders of posture and equilibrium

70
Q 
wide-based, unsteady gate indicative of impaired balance (like the staggering of an intoxicated person)
Dysdiadochokinesi -
Intention tremor
b. Dysmetria (past-pointing)
\:Ataxia
A

Ataxia

71
Q 
inability to control the distance, power, and speed of a voluntary movement
Dysdiadochokinesi -
Intention tremor
b. Dysmetria (past-pointing)
\:Ataxia
A

b. Dysmetria (past-pointing):

72
Q 
oscillations at the end of a movement due to loss of coordination between antagonistic muscle groups
choices 
Dysdiadochokinesi -
Intention tremor
b. Dysmetria (past-pointing)
\:Ataxia
A

Intention tremor

73
Q 
- inability to perform rapid alternating movements (stopping and quickly reversing a movement repeatedly)
Dysdiadochokinesi -
Intention tremor
b. Dysmetria (past-pointing)
\:Ataxia
A

Dysdiadochokinesi -

74
Q
  • The lower motor neurons also receive sensory input from sensory receptors located in the skeletal muscles or on the body surface as a part of a ____
A

reflex arc -

75
Q

is a subconscious stimulus-response movement mechanism

A

A reflex

76
Q

is the set of anatomical components that carry out a reflex

A

A reflex arc

77
Q

: a sensory organ that generates receptor potentials (local response) when stimulated

A

Receptor:

78
Q

transmits action potentials from the receptor into the spinal cord and terminates on an interneuron or efferent neuron

A

Afferent neuron:

79
Q

short neurons that either redirect input from one side of the spinal cord to the other or change an excitatory signal into an inhibitory signal; not every reflex arc includes an interneuron

A

Interneuron

80
Q

usually the lower motor neuron (final common pathway); transmits action potentials from the spinal cord to the effector (the same skeletal muscle where the receptor is located)

A

Efferent neuron

81
Q

skeletal muscle fibers that produce the response

A

Effector:

82
Q

Purpose of a reflex

A

a. feedback mechanisms that maintain appropriate muscle tone (resistance to passive stretch or “stiffness”); the muscle stretch reflex, for example
b. protective; the flexor withdrawal reflex, for example, causes you to withdraw an extremity from a painful stimulus
c. Clinically, assessment of the presence, absence, or strength of a reflex is important in the diagnosis and localization of neurologic injuries

83
Q
  • Interruption of a reflex arc at any point will abolish the response (interruption of a lower motor neuron will cause _____ while upper motor neuron injury can cause ____)
A

flaccid paralysis, hyperreflexia

84
Q

Reflex arc of muscle stretch reflex (deep tendon reflex)

A
  1. Receptor: muscle spindle stretch receptor stimulated by a rapid stretch of the muscle sends a signal to the
  2. Afferent neuron: the distal end of the peripheral process spirals around the muscle fibers inside the spindle which depolarizes and activates the
  3. Efferent neuron: the lower motor neuron (the same skeletal muscle where the receptor is found) causing
  4. a muscle contraction -
85
Q
  • A reflex arc can be produced diagnostically by striking the taut tendon of a muscle with ____
A

a reflex hammer

86
Q
  • The sudden stretch opens mechanically gated channels in the afferent neuron, producing a receptor potential whose amplitude is proportional to ____
A

the amount of stretch

87
Q

input to basal nuclei via the striatum comes from______ and ______

A

Motor areas

substantial nigra

A&P module 4 CNS (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions