Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Human physiology > Lecture 9: Spinal cord and Brainstem Control of Motor Function I > Flashcards

Lecture 9: Spinal cord and Brainstem Control of Motor Function I Flashcards

1
Q

Interneuron characteristics

A 
30x as numerous as anterior motor neurons
Bipolar shape
Small and highly excitable
Capable of spontaneous activity
Most are inhibitory- GABA
Some excitatory- Glutamate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Renshaw cells are what located where and use what NT

A

Inhibitory cells located in anterior horns of spinal cord

Glycine

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

Renshaw cells receive collateral branches from ___

A

Alpha motor neurons

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

Renshaw cells transmit inhibitory signals to who resulting in what

A

Surrounding motor neurons, resulting in lateral inhibition and enhanced fluidity of limb movement

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

What is it called when Renshaw cell transmits inhibitory signal to same motor neuron

A

Recurrent inhibition/negative feedback

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

Sensory and motor neurons are afferent/efferent

A

Sensory afferent

Motor efferent

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

Upper neuron axons project

A

To spinal cord interneurons or lower motor neuron

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

Lower motor neuron axons project

A

From spinal cord to effector

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

Neurotransmitter of upper lower neuron to lower motor neuron

A

Glutamate

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

Lower motor neurons found in

A

Anterior gray portion of spinal cord or cranial nerve nuclei of brain stem

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

LMN use what neurotransmitter

A

Acetylcholine

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

Cranial nerves are unique _____

A

Lower motor neurons

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

Motor unit

A

Single motor neuron and muscle fibers it innervates

Composed of extrafusal fibers

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

Motor neuron pool

A

Group of motor neurons that innervate fibers within the same muscle

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

Small motor neuron characteristics

A

Innervate few muscle fibers
Lowest thresholds
Fire first
Small force

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

Large motor neuron characteristics

A

Innervate many muscle fibers
Highest thresholds
Fire last
Largest force

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

Recruitment

A

Refers to the increase in tension of muscle contractions by the activation of additional motor units

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

Ia inhibitory neurons

A

Inhibits antagonistic muscle
Signal from muscle spindle
Avoids spasticity

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

Ib inhibitory neurons

A

Autogenic inhibition reflex
Golgi tendon activated with stretch
Connects with Ib to inhibit same muscle
Responsible for smooth muscle contraction and protects muscles from tears

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

Excitatory interneurons involved in and receive stimuli from

A

Spinal reflex to remove extremity from damaging stimulus

Sensory group III afferents

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

Muscle spindle consists of and description

A

Group Ia and group II afferents (small gamma MNs)
Arranged in parallel with extrafusal fibers
Detect both dynamic and static changes in muscle length-corrects for increase in muscle length
Consists of 3-12 intrafusal fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Golgi tendon organ consists of/descripiton

A

Group Ib afferents
Arranged in series with extrafusal fibers
Detect muscle tension

23
Q

Pacinian corpuscle consists of/description

A

Group II afferents

Detect vibration

24
Q

Free nerve endings consist of/description

A

Group III and IV afferents

Detect noxious stimuli

25
Sensory nerve fiber groups I-IV myelination
Groups I-III are myelinated, IV is not
26
A fibers are
Somatic, myelinated
27
Types of A fibers and description
Alpha-Largest, Type I Beta- Type II Gamma Delta- smallest,, type IV
28
B fibers
Lightly myelinated | Preganglionic fibers of ANS
29
C fibers
Unmyelinated Found in somatic and autonomic systems Also referred to as type IV
30
Sensory fibers grouped from high speed to low speed
A-alpha/A-beta 30-120m/sec A-delta- 4-30m/sec C fibers- less than 2.5m/sec
31
Nuclear bag fibers
Intrafusal Detect rate of change in muscle length Innervated by group Ia Afferents & dynamic y Efferents Multiple nuclei in central bag like configuration
32
Nuclear chain fibers
``` Intrafusal Detect static change in muscle length Innervated by group II Afferents and static y Efferents More numerous than nuclear bag Nuclei arranged in single row ```
33
Alpha motor neuron characteristics
Most numerous Innervate effector-skeletal muscle NT- Acetycholine
34
Gamma motor neuron characteristics
Innervates intrafusal fibers Keeps muscle spindles taut NT- Acetycholine
35
Muscle spindle Ay neurons suppy
Supply small intrafusal fibers in middle of muscle spindle
36
Muscle spindle gamma-dynamic
Excite nuclear bag intrafusal fibers
37
Muscle spindle gamma-static
Excite nuclear chain intrafusal fibers
38
Brain areas that control gamma motor neurons
Bulboreticular region of brain stem Cerebellum Basal nuclei Cerebral cortex
39
Dynamic stretch reflex
Signals transmitted from primary nerve endings | Opposes sudden changes to muscle length
40
Static reflex
Transmitted by both primary and secondary endings | Causes degree of muscle contraction to remain relatively constant
41
Stretch reflex description
Stretching of muscle stretches Ia afferent fibers Ia afferents synapse directly on a-motor neurons of same muscle The muscle contracts and decrease tension on spindle Synergistic muscles are activated and antagonistic inhibited
42
Golgi tendon organ description
Arranged in series with extrafusal fibers Stimulated by contracting or stretching of muscle Opposite of the stretch reflex
43
Golgi tendon organ circuitry
Type Ib afferent--> inhibitory interneuron--> anterior motor neuron
44
What is after-discharge
Result of persistent neural activity in polysynaptic circuits. It prevents the muscle from relaxing for some time
45
Premotor and supplementary motor areas
Generate a plan for movement and transmit to primary motor cortex Signals generated here cause more complex patterns of movement
46
Supplemental vs premotor areas
Premotor cortex develops a motor image of the total muscle movement to be performed Supplementary cortex programs complex sequences and is responsible for mental rehearsal of a movement
47
Posterior motor cortex circuit
Posterior MC--> primary MC | Posterior MC--> basal nuclei/thalamus--> primary MC
48
Motor cortex- pyramidal cells in what layer/ input signals inter what layer
5th-pyramidal | 2-4th- input signals enter
49
Neurons in 6th layer communicate with
Other regions of the cerebral cortex
50
Upper motor neuron full description
All in CNS Orginate in cerebral cortex, cerebellum, brain stem Form descending tracts
51
Lower motor neuron full description
Begin in CNS from anterior horns of SC or brainstem Made up of alpha motor neurons A-alpha Make up spinal and cranial nerves
52
Medial activation system
Innervate postural and girdle muscles
53
Lateral activation system
Associated with distally located muscles for fine movement
54
Nonspecific activating system
Facilitate local reflex arcs

Human physiology (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions