Motor Fxn I: Part One

Question 1

Stretch reflex Characteristics

Answer 1

• Stretch stretches Group Ia Afferent
• Ia synapse on AMN of SAME Muscle
• Muscle Contracts to decrease tension on Spindle

Question 2

Types of intrafusal fibers

Answer 2

• Nuclear BAG

- Nuclear CHAIN

Question 3

Golgi tendon organ

Answer 3

• Group Ib Afferents
• Arranges in SERIES w/ EF fiber
• Detect Tension

Question 4

Lower motor neurons are classified into what categories?

Answer 4

• Alpha
• Beta
• Gamma

Question 5

Nuclear bag fibers

• Detection
• Innervation
• Nuclei

Answer 5

• Detect Change in LENGTH
• Ia and dynamic Gamma efferent
• Mult. Located in the Bag

Question 6

Gamma motor neurons do what?

Answer 6

Keep Muscle SPINDLE Taught

Question 7

Characteristics of Interneurons

Answer 7

• Bipolar shape
• Capable of Spontaneous activity
• Responsible for most of SPINAL cord integrative fxn

Question 8

Motor Nerve Cells deal with what kind of movement?

Answer 8

Voluntary movement

Question 9

Fxn of Renshaw cells

Answer 9

• Receive branches from AMN
• Transmit Inhibitory signals to surrounding MN
  (Lateral Inhibition)
• Enhance FLUIDITY of limb movement

Question 10

The Afferent neurons are ____.

Answer 10

Sensory

Question 11

Muscle Spindle Fxn

Answer 11

• Dynamic Stretch Reflex
• Static Reflex
• Damping (Prevents Jerking)

Question 12

Bran Areas that control Gamma Fibers

Answer 12

• Bulboreticular Region of Brain Stem
• Cerebellum
• Basal Nuclei
• Cerebral cortex

Question 13

Excitatory Interneurons

Answer 13

• Spinal Reflex
  (Step on a Tack)
• Ipsilateral and Contralateral signals
• Can cut the head off of a chicken and it can still move*

Question 14

Result of Stretch reflex

Answer 14

Synergistic Muscles are Activated and Antagonistic muscles are inhibited

Question 15

Nuclear Chain fibers

• Detection
• Innervation
• Nuclei

Answer 15

• STATIC Change
• Group II and static gamma
• More numerous than NBF
• Nuclei located in a chain

Question 16

Efferent Neurons are _____.

Answer 16

Motor

Question 17

What NT do RENSHAW cells use?

Answer 17

Glycine

Question 18

NT for Alpha and Gamma MN

Answer 18

Both use ACh

Question 19

Golgi tendon Organ

• Orientation to EFF
• Stimulation
• Detection
• Overall fxn

Answer 19

• Arranges in Series w/ EF Fibers
• Stimulated by Contraction or Stretch
• Detects Tension
• Deals with RELAXATION of muscles to heavy load

Question 20

The Babinski reflex is seen in ____.

Answer 20

Infants

Question 21

1 AMN can innervate how many muscle fibers?

Answer 21

3000+

Question 22

What are the types of Motor Neurons in the Spinal Cord?

Answer 22

• Alpha

- Gamma

Question 23

Lesion effects on REFLEXES: UMN vs LMN

Answer 23

UMN:
- Increased

LMN:
- Absent

Question 24

Major Volitional Movement go through what Tract in the Spinal Cord?

Answer 24

Cortico-Spinal Tract

• UMN

Question 25

Pacinian Corpuscles

Answer 25

- Group II | - Detect VIBRATIONS

Question 26

Lower Motor neurons go from ______ to ______.

Answer 26

- Spinal cord | - Effector (Sk. Muscle)

Question 27

T/F: INTERNEURONS are 30x more Numerous as Ant. Motor Neurons

Answer 27

True

Question 28

Motor Neuron pool

Answer 28

AMN that innervate a MUSCLE

Question 29

Does the muscle spindle fxn as a motor or sensory receptor?

Answer 29

Sensory

Question 30

Excitatory IN use _____ and Inhibitory IN use ______.

Answer 30

- GABA | - Glutamate

Question 31

Ib Inhibitory Neurons

Answer 31

- AUTOGENIC Inhibition reflex - GOLGI tendon activated with Stretch - Responsible for smooth muscle contraction - Protects from tears

Question 32

Free Nerve Endings

Answer 32

- Group III and IV Afferent | - Detect Noxious stimuli

Question 33

What is the NT of the UMN to the LMN?

Answer 33

Glutamate

Question 34

Ia Inhibitory Neurons

Answer 34

- Inhibits ANTAGONISTIC muscle | - Avoids Spasticity

Question 35

LMN terminate at Effector and use what NT

Answer 35

ACh

Question 36

Large Motor neurons - Muscle innervation - Threshold - Firing time - Force

Answer 36

- Many - High - Fire LAST - LARGE

Question 37

Small Motor neurons - Muscle innervation - Threshold - Firing time - Force

Answer 37

- Innervate Few muscle fibers - LOW threshold - Fire FIRST - Small force

Question 38

Golgi Tendon Reflex is _____ to Stretch Reflex

Answer 38

Opposite

Question 39

Motor Unit Consists of what?

Answer 39

- A SINGLE Motor Neuron | - The muscle FIBERS it Innervates

Question 40

Where are the cell bodies of Motor neurons located?

Answer 40

3 places: 1. Motor Cortex 2. Brain Stem 3. Spinal Cord

Question 41

What are the INTERNEURONS in the Spinal Cord called?

Answer 41

RENSHAW Cells

Question 42

Muscle Spindle

Answer 42

- Group Ia and II Afferents - Arranges in PARALLEL w/ EF fiber - Direct both Dynamic and STATIC changes is muscle length

Question 43

Ia Inhibitory Neurons receive signals from what?

Answer 43

Muscle SPINDLE

Question 44

Lesion effects on Muscle Tone: UMN vs LMN

Answer 44

UMN: - Spastic LMN: - Flaccid

Question 45

In the Spinal Cord, the Sensory fibers are ____ and the Motor Neurons are ____.

Answer 45

- Lateral | - Medial

Question 46

Are Cranial Nerve UMN or LMN?

Answer 46

LMN