Lecture 1 - LMN and Muscles : Part 1

Question 1

The corticospinal tracts are only in _________?

Answer 1

Mammals, not all vertebrate animals

Question 2

Where is the corticospinal tract located in human beings?

Answer 2

Ventral horn only (grey matter)

Question 3

Where is the corticospinal tract located in other mammals?

Answer 3

Both ventral and dorsal horns

Question 4

Where is the rubrospinal tract located in human beings?

Answer 4

Intermediate zone (UE only)

Question 5

Where is the rubrospinal tract located in animals?

Answer 5

The whole spinal cord

Question 6

True or false: The rubrospinal tract is located in all vertebrates.

Answer 6

False, not all vertebrates

Question 7

Where is the reticulospinal tract descend to, and where does it go to?

Answer 7

Ventral horn and the whole spinal cord

Question 8

True or false: The reticulospinal tract is shown in all vertebrates.

Answer 8

True

Question 9

What is the red nucleus in charge of?

Answer 9

Skilled learning

Question 10

What are the functions of the motor control tracts in the anterior funiculus?

Answer 10

Gross motor skills and Posture

Question 11

What are the four motor control tracts in the anterior funiculus?

Answer 11

Medial vestibulospinal tract
Medial corticospinal tract
Pontine reticulospinal tract
Lateral vestibulospinal tract

Question 12

What is the function of the medial vestibulospinal tract?

Answer 12

Gross motor/postural control of bilateral neck extension

Question 13

Where does the medial vestibulospinal tract end?

Answer 13

Ends in the neck and upper thoracic

Question 14

What is the function of the medial corticospinal tract?

Answer 14

Bilateral postural flexor muscle control

Question 15

What is the function of the pontine reticulospinal tract?

Answer 15

Gross motor/postural bilateral proximal extremity extensors

Question 16

What is the function of the lateral vestibulospinal tract?

Answer 16

Gross motor/postural control of ipsilateral proximal extremity extensors

Question 17

What are the functions of the motor control tracts in the lateral funiculus?

Answer 17

Fine motor control and skills

Question 18

What is the function of the medullary reticulospinal tract?

Answer 18

Fine motor control of distal extremity flexors

Question 19

What is the function of the rubrospinal tract?

Answer 19

Fine motor control of distal UE flexors

Question 20

Where does the rubrospinal tract end?

Answer 20

End in the neck and upper thoracic

Question 21

What is the function of the lateral corticospinal tract?

Answer 21

Fine motor control of distal extremity

Question 22

What are the 3 motor control tracts in the lateral funiculus?

Answer 22

Medullary reticulospinal tract
Rubrospinal tract
Lateral corticospinal tract

Question 23

What is a motor neural pool?

Answer 23

LMNs for one muscle aligned in a column

Question 24

What is the order of the LMNs in the motor neural pool?

Answer 24

Cranial to caudal for proximal to distal muscle innervation

Question 25

What is the distribution of LMNs like in the motor unit?

Answer 25

They are intermingled, not himogenous

Question 26

In a motor unit, all muscle fibers are innervated by what?

Answer 26

A single LMN

Question 27

How many ATP are in glucose?

Answer 27

36

Question 28

What are the muscle fiber types mainly found in red muscle?

Answer 28

Type 1

Question 29

What are Type 1 muscle fibers?

Answer 29

Slow twitch Slow fatigue resistance (SR) High concentration of mitochondria Less glycogen

Question 30

What are the muscle fiber types are mainly found in white muscle?

Answer 30

Type 2

Question 31

What does a high concentration of mitochondria do in type 1 muscle fibers?

Answer 31

Degrades glucose entirely and creates more ATP so that the muscle doesn't fatigue as fast

Question 32

What are Type 2a muscle fibers?

Answer 32

Fast twitch Fatigue resistance (FR) Medium concentration of mitochondria and glycogen

Question 33

What are Type 2b muscle fibers?

Answer 33

Fast twitch Fatigable (FF) Low concentration of mitochondria but HIGH concentration of glycogen

Question 34

How does type 2b fibers get more ATP?

Answer 34

Through glycolysis

Question 35

What are the components of small LMNs?

Answer 35

SR fibers Less powerful Last hours Produce small force

Question 36

What are the functions of small LMNs?

Answer 36

Fine motor (lateral ventral horn) and postural (medial ventral horn) control

Question 37

What is the function of the medium LMNs?

Answer 37

Gross motor and power

Question 38

What are the components of medium LMNs?

Answer 38

FR fibers More powerful Lasting almost 1 hour Produce medium amount of force

Question 39

What are the components of large LMNs?

Answer 39

FF fibers Most powerful Lasting ~1 minute Produces large force

Question 40

What are the functions of large LMNs?\

Answer 40

Gross motor and power

Question 41

Which type of muscle fibers are mainly in the thenar eminence? Which kind of LMNs control these fibers?

Answer 41

SR fibers Fine motor Small LMNs

Question 42

What do motor unit size depend on?

Answer 42

Functions

Question 43

What is the motor unit size of gross motor functions?

Answer 43

Large 1 LMN to hundreds of muscle fibers FR/FF muscle fibers Medium and large LMNs Large motor unit

Question 44

What is an example of a gross motor function with a large motor unit?

Answer 44

Gastrocnemius

Question 45

What is the motor unit size of fine motor functions?

Answer 45

Small 1 LMN innervates several muscle fibers Type 1 muscle fibers Small LMNs Small motor unit

Question 46

Are the eye muscles slow twitch or fast twitch muscles?

Answer 46

Fast twitch, because saccades is very fast

Question 47

Where is the presynaptic potential produced?

Answer 47

Axonal terminial

Question 48

Where is the postsynaptic potential produced?

Answer 48

Muscle cell

Question 49

What is considered unfused tetanus and fused tetanus?

Answer 49

Unfused: AP frequency over 80 HZ Fused: AP frequency over 100 HZ

Question 50

What is the order of recruitment of motor units?

Answer 50

SR (slow) FR (medium) FF (large)