W7: Motion

Question 1

define

Motor System

Answer 1

All our muscles and neurons that control them

Question 2

state

Division of Motor Control (2 Parts)

Answer 2

1. Spinal cord (command and control of coordinated muscle contraction
2. Brain (command and control and often unpredictable environment)

Question 3

state

2 Categories of Muscles

Answer 3

1. Smooth
2. Striated

Question 4

state

2 Categories of Striated Muscles

Answer 4

1. Skeletal
2. Cardiac

Question 5

define

Skeletal Muscle

Answer 5

Constitutes bulk of the muscle mass of the body and functions to…
move bones around joints, move eyes in head, inhale-exhale, control facial expression, produce speech

Question 6

define

Muscle Fibers

Answer 6

Cells of skeletal muscle
-> Each fiber innervated by a single axon branch from CNS

Question 7

define

Somatic Motor System

Answer 7

tba

Question 8

define

Ventral Horn

Question 9

define

Lower Motor Neurons (LMN)

Question 10

define

Higher Motor Neuron

Question 11

define

Final Common Pathway (for Control of Behaviour)

as defined by Sherrington

Question 12

Y/ N: Are skeletal muscles evenly distributed throughout the body?

Answer 12

No

Question 13

Y/N: Are lower motor neurons evenly distributed within the spinal cord?

Answer 13

No

Question 14

state

2 Types of Lower Motor Neurons

(in spinal cord)

Answer 14

1. Alpha
2. Gamma

Question 15

state function

Alpha Motor Neurons

Answer 15

Directly trigger the generation of force by muscles

Question 16

define

Motor Unit

Answer 16

One alpha motor neuron and all the muscle fibers it innervates collectively make up elementary component of motor control

Question 17

define

Muscle Contraction

Answer 17

Results from the individul and combined actions of motor units.

Question 18

define

Motor Neuron Pool

Answer 18

Collection of alpha neurons that innervates a single muscle

Question 19

2 ways

How do alpha motor neurons acheive graded control of muscle contraction?

Answer 19

1. Varying firing rate
2. Recruiting additional synergistic motor units

Question 20

define

Size Principle

Question 21

state

3 Sources of Input to Alpha Motor Neurons

Answer 21

1. Sensory input (from dorsal ganglion)
2. Upper motor neurons (from upper motor neurons in motor cortex and brain stem)
3. Interneurons (in spinal cord)

Question 22

List Types

Fibers

Answer 22

1. Slow (S)
2. Fast (F)

Fatigue-Resistant (FR) & Fast-Fatiguable (FF)

Question 23

define

Excitation-Contraction Coupling

Answer 23

Process by which an AP (excitation) triggers the release of Ca2+ from an organelle inside the muscle fiber which leads to the contraction of the fiber.

Question 24

state basic principles

Sliding Filament Theory

Question 25

# define Muscle Spindle | aka Stretch Receptor

Answer 25

Consists of several types of specialised skeletal muscle fibers contained in a fibrous capsule (found deep within most skeletal muscles)

Question 26

# define Proprioceptors

Question 27

Group Ia Axons

Question 28

Group Ib Axons

Question 29

# define Stretch Reflex

Question 30

# define Extrafusal Fibers

Question 31

# define Intrafusal Fibers

Question 32

# list components Gamma Loop

Question 33

# define Golgi Tendon ORgans

Answer 33

**Another sensor of skeletal muscle, acting like a very sensitive strain gauge monitoring muscle tension (force of contraction)** Located at the junction of the muscle and the tensons are are innervated by group Ib sensory axons

Question 34

# define Flexor (Withdrawal) Reflex

Question 35

Factors Influencing Flexor Reflex

Question 36

Crossed-Extensor Reflex | think: walking / stepping on pin with one leg

Question 37

Central Pattern Generators

Question 38

# list order, NS areas involves, function 3 Levels of Central Motor System | (hierarchy) ## Footnote think about the baseball pitcher + batter

Answer 38

1. HIGHEST LEVEL - neocortex + basal ganglia - *strategy* 2. MIDDLE LEVEL - motor cortex + cerebellum - *tactic* 3. LOWEST LEVEL - brain stem + spinal cord - *execution*

Question 39

How does the brain communicate with the motor neurons of the spinal cord?

Answer 39

Axons from the brain descend through the spinal cord along two major groups of pathways.

Question 40

# list 2 Groups of Pathways (Descending Spinal Tracts)

Answer 40

1. Lateral Pathways 2. Ventromedial Pathways