Brainscape's Knowledge GenomeTM

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


See full index

SP15 Neuroanatomy - Dr. Pierson > Lecture 5 - Descending Motor Systems > Flashcards

Lecture 5 - Descending Motor Systems Flashcards

1
Q

Upper motor neurons (UMN) originate in the motor region of the _____ ______ or the ________ and synapse on lower motor neurons.

A
  • cerebral cortex

- brainstem

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

Lower motor neurons (LMN) originate in the ______ ______ gray matter or _____ ____ _____ of the spinal cord and are the last in a chain of neurons.

A
  • anterior horn

- anterior nerve roots

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

Lower motor neurons (LMN) innervate _______ muscle, and signal muscle ________.

A
  • striated

- contraction

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

Lower Motor Neurons:

Extrafusal muscle fibers use _____ motor neurons. Intrafusal muscle fibers use ______ motor neurons.

A
  • alpha

- gamma

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

LMN lesions can result in loss of muscle tone called ______.

A

atonia

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

LMN lesions can result in loss of myotatic (knee jerk) reflex called _______.

A

areflexia

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

LMN lesions can result in inability of muscles to contract called _____ ______.

A

flaccid paralysis

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

LMN lesions can result in spontaneous muscle contractions called ________.

A

fasciculations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

LMN lesions can result in loss of muscle tissue called _____.

A

atrophy

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

LMN lesions can result in irregular contractions of individual muscle fibers called _______.

A

fibrillations

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

UMN lesions result in _____ _______.

A

spastic paralysis (paresis)

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

UMN lesions resulting in increased resting muscle tension called _____.

A

hypertonia

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

UMN lesions resulting in twitching/spastic reflexes called ________.

A

hyperreflexia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

UMN lesions may result in a characteristic upward extension of the toes (instead of flexion) upon stimulation of the plantar surface; this is called the _______ sign.

A

Babinski

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

Lesions on LMN result in ______ atrophy, while UMN lesions result in _____ atrophy.

A
  • severe

- mild

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

As a result of UMN lesions, rapid series of alternate muscle contractions in response to the stretching of a muscle is known as a ______.

A

clonus

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

One LMN axon in the ventral root divides into many terminal _____ to innervate a muscle. Each of these ends at one _____ _____ _____.

A
  • branches

- neuromuscular junction (NMJ)

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

LMN controlling axial muscles are _____ to those controlling distal muscles. Neurons controlling flexors are ______ to the extensor group.

A
  • medial

- posterior

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

1 motor neuron + all myofibers it innervates = ____ ____.

A

motor unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

TRUE or FALSE:

A larger/less specific muscle has more myofibers per motor unit.

A

TRUE. More specific/smaller muscles have fewer fibers per motor unit.

Ex: Extraocular = 10 myofibers/unit; Gastrocnemius = 1,000/unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

3 Types of muscle fibers:

  • _____ fibers contract weakly for long periods of time.
  • _____ fibers contract strongly for short & long periods.
  • _____ fibers contract very strongly for very short times.
  • There [is/is not] mixing of the different myofibers.
A
  • standing
  • running
  • jump
  • is not
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Type ___ muscles are for sustained weight/force bearing, and high in lipids and mitochondria, slow twitch, low glycogen. (duck breast)

Type ___ muscles are for sudden movements, low in lipids/mitochondria, fast twitch, high glycogen. (turkey breast)

A
  • I
  • II
  • “one (type 1) slow (twitch) fat (lipid-rich) red (appearance) ox (oxidative, mitochondria-rich)”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Higher energy (such as jump type) motor units are [more/less] prone to fatigue, because [more/less] motor units are used than lower energy (such as stand).

A
  • more

- more

24
Q

TRUE or FALSE:

Basal ganglia, the cerebellum, and the association cortex play a key role in signaling the LMN for complex motor output.

A

FALSE. Basal ganglia, cerebellum, and association cortex only signal UMN. The UMN then signal the LMN.

25
Q

TRUE or FALSE:

Damage to UMN’s contribute to the muscular weakness and atrophy because the muscle receive inadequate motor impulses.

A

FALSE. UMN damage only results in incoordination; LMN damage results in muscle weakness.

26
Q

The premotor cortex plans movement, tells the motor cortex, then LMN what to do. This top-down signaling is ________ control.

A

hierarchical

27
Q

Direct communication of the premotor cortex and LMN without the motor cortex is referred to as _____ control.

A

parallel

28
Q

The basal ganglia and cerebellum output to the _____ _____ and motor cortex, but NOT the _____ _____.

A
  • premotor cortex

- spinal cord

29
Q

Descending motor neurons mostly terminate on _____ horn neurons and ________.

A
  • dorsal *
  • interneurons
  • double check this… motor neurons should synapse in the anterior horn shouldn’t they?
30
Q

6 Descending Motor Pathways:

  • Cortex to spinal cord = ________ tract
  • Cortex to brainstem = _________ tract
  • Cortex to basilar pons = _______ tract
  • Red nucleus to contralateral anterior horns = ________ tract
  • Reticular formation (medulla, pons) to medial anterior horns = ______ tract
  • Vestibular nucleus to spinal cord = ________ tract
A
  • corticospinal tract (UMN)
  • corticobulbar
  • corticopontine
  • rubrospinal
  • reticulospinal
  • vestibulospinal
31
Q

There are 5 areas in the cerebrum associated with the corticospinal tract. From anterior to posterior, these areas are:

  • The _______ area in the frontal lobe
  • The ______ ______ area in the precentral gyrus
  • The ______ ______ area in the postcentral gyrus
  • The ______ ______ _______ (most posterior)
  • The ______ ______ area on the medial frontal lobe
A
  • premotor (area 6) (20% fibers)
  • primary motor (area 4) (40% fibers)
  • somatic sensory (areas 1, 2, 3) (25% fibers)
  • superior parietal lobule (areas 5, 7) (5% fibers)
  • supplementary motor area (area 6) (10% fibers)
32
Q

TRUE or FALSE:

There are both motor and sensory homunculi, located in the primary motor cortex and somatic sensory cortex, respectively.

A

TRUE.

33
Q

The primary motor area is responsible for ______ voluntary movements, and control of fine ______ movements. It projects to both the _____ and _____ ____. Lesions affect _______ musculature.

A
  • contralateral
  • digital
  • brainstem
  • spinal cord
  • contralateral
34
Q

The premotor area plans movements in response to external ______. It controls ______ and _____ musculature (trunk, shoulder, hip), and may assemble _______ (responsive feeling) facial movements.

A
  • stimuli
  • proximal
  • axial
  • empathetic
35
Q

Most premotor cortex fibers project to the ______ motor cortex and _______ ______ of the brainstem.

A
  • primary

- reticular formation

36
Q

Premotor cortex lesions result in moderate weakness of ________ proximal muscles and inability to associate _____ movements to visual and verbal stimuli.

A
  • contralateral

- hand

37
Q

The part of the brain that learns new sequences, assembles old sequences, and “imagines” movements is the ________ motor area. It projects to the _____ and _____ motor areas for output.

A
  • supplementary
  • premotor
  • primary
38
Q

In the parietal lobe of the cerebrum, just posterior to the central sulcus is the _____ _____ area responsible for sensory input. Directly posterior to this is the _____ _____ lobule on the superior aspect of the parietal lobe.

A
  • somatic sensory

- superior parietal

39
Q

In response to sensory input, the _____ _____ area directs motor patterns in the _____ motor area. Input to this region is received from the _____ and _____ _____.

A
  • somatic sensory
  • primary
  • brainstem
  • spinal cord
40
Q

The corticospinal tract (CST) originates in the ______ _______ area in the ______ _______ of the cerebral cortex. It also has some fibers originating from ____ cells.

A
  • primary motor
  • precentral gyrus
  • Betz
41
Q

CST collaterals project to what 6 areas?

A
  • basal ganglia
  • thalamus
  • reticular formation
  • posterior column nuclei
  • posterior horn
  • intermediate horns
42
Q

CST impairment is associated with _____ paralysis and impairment of fine ____ movement.

A
  • flaccid

- finger

43
Q

The CST leaves the mesencephalon (midbrain) at the _____ _____. It then travels through the anterior ______ _____ of the pons, the _____ ______ of the medulla, and decussates at the __________ junction.

A
    • cerebral peduncle
  • basis pontis
  • medullary pyramid
  • spinomedullary
  • the cerebral peduncle is NOT part of the cerebrum
44
Q

In the ______ CST, 85% of fibers decussate in the medulla and descend in the ______ funiculus (white matter or spinal cord). In the ______ CST, 15% of fibers do not decussate, and descend in the ______ funiculus.

A
  • lateral
  • lateral
  • anterior
  • anterior
45
Q

TRUE or FALSE:

The CST is somatotopically organized.

A

TRUE

46
Q

Clinically, the CST can be damaged by strokes when emboli travel up the internal carotid artery and lodge in the ______ ______ artery.

A

middle choroidal

47
Q

The CST is a _____ tract because it travels through the pyramid of the rostral medulla.

A

pyramidal

48
Q

Control of shoulder and proximal arm musculature is associated with the _______ tract.

A

rubrospinal

49
Q

Control of axial musculature for walking is associated with the ________ tract.

A

reticulospinal

50
Q

Control of axial musculature for balance is associated with the _________ tract.

A

vestibulospinal

51
Q

Head turning reflexes in response to visual stimuli are associated with the ________ tract.

A

tectospinal

52
Q

The vestibulospinal tract receives input from the ______ end organ and _______. The [anterior/lateral] tract travels through the lateral funiculus ipsilaterally for ______ muscle reflexes. The [anterior/lateral] tract travels through the anterior funiculus bilaterally for _____ movements in response to gravity.

A
  • vestibular
  • cerebellum (balance)
  • lateral
  • antigravity
  • anterior
  • head
53
Q

The rubrospinal tract receives input from the _____ and _____ motor cortices, and the ______. It decussates at the ventral ______ area, and travels through the [anterior/lateral] funiculus. Innervation is [contralateral/ipsilateral]. It facilitates muscle tone for shoulder and _____ flexors.

A
  • premotor
  • primary
  • cerebellum
  • tegmental
  • lateral
  • contralateral
  • arm
54
Q

The reticulospinal tract originates in the ______ ______. It receives input from the _____ _____ and _____ _____ cortices. It courses through the medial longitudinal _______ of the brainstem, then the [anterior/lateral] funiculus of the spinal cord [bilaterally/ipsilaterally]. Its function is the support of ______ motor actions like ______.

A
  • reticular formation
  • primary motor
  • somatic sensory (pain associated w/ reticular formation)
  • fasciculus
  • anterior
  • bilaterally
  • rhythmic
  • walking
55
Q

The ________ pathway originates in the face/mouth area of the ______ ______ cortex, and inputs directly on cranial nerves and interneurons in the reicular formation. It ceases to exist after reaching its target nuclei.

A
  • corticobulbar

- somatic sensory

56
Q

The corticobulbar pathway directly influences cranial nerves ___, ___, ___, ___, and the ______ _____ of the reticular formation.

A
  • CN V
  • CN VII
  • CN XI
  • CN XII
  • nucleus ambiguus
57
Q

The corticobulbar pathway contralaterally innervates ______ facial muscles and bilaterally innervates ______ facial muscles through the ______ ______ nucleus. Therefore, unilateral damage inhibits smiling, but doesn’t affect forehead movement.

A
  • lower
  • upper
  • facial motor

SP15 Neuroanatomy - Dr. Pierson (10 decks)

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