Section 5, Exam 2

Question 1

A specialized proprioceptor that sends information to the CNS about muscle length and the velocity of stretch (mm/s)

Answer 1

Muscle spindle

Question 2

Muscle spindles are oriented in ______ to extrafusal muscle fibers throughout the fleshy part of skeletal muscle

Answer 2

Parallel

Question 3

What type (motor or sensory) of innervation does the muscle spindle receive?

Answer 3

Both motor and sensory (group Ia and group II)

Question 4

What is the only receptor that receives both sensory and motor innervation?

Answer 4

The muscle spindle

Question 5

What are muscle spindles enclosed in?

Answer 5

A fusiform shaped connective tissue capsule

Question 6

Skeletal muscle fibers outside the capsule are termed ________.

Answer 6

Extrafusal muscle fibers

Question 7

Term used to refer to structures inside the fusiform shaped connective tissue capsule

Answer 7

intrafusal

Question 8

On average, about how many nuclear bag fibers do muscle spindles have? Nuclear chain fibers?

Answer 8

2; 4-6

Question 9

When A gamma efferent axons stimulate muscle fibers, what will happen to the middle of the muscle spindle?

Answer 9

It will stretch due to contraction in the polar region in the m. spindle

Question 10

The property that makes material resistant to a change in form, shape, or structure

Answer 10

Viscosity

Question 11

The equatorial region of both the nuclear bag and chain fibers are ______ viscous comparison to the polar regions

Answer 11

Less viscous

Question 12

The polar regions of both the nuclear bag and chain fibers are _____ sensitive to stretch or length change

Answer 12

Less

Question 13

What region of the muscle spindle contains more contractile proteins?

Answer 13

Polar regions

Question 14

Polar regions are more resistant to change its form or structure because of ___________ between protein molecules.

Answer 14

Electrostatic attraction

Question 15

The equatorial regions of both the nuclear bag and chain intrafusal muscle fibers are innervated by?

Answer 15

Ia (A alpha) afferent axons

Question 16

What does the “a” indicate in the Ia axon classification?

Answer 16

Innervation of the annulospiral nerve

Question 17

What are annulospiral nerve endings also known as?

Answer 17

The primary endings

Question 18

In most cases, what type of intrafusal muscle fiber does Group II afferent axons innervate?

Answer 18

Nuclear chain fibers (sometimes nuclear bag, but significantly less instances)

Question 19

Where in the muscle spindle do Group II axons innervate?

Answer 19

Polar region

Question 20

True or False:

Group II has a slower AP conduction velocity than the Ia axons.

Answer 20

True; they also have smaller sensory axons

Question 21

What are group II nerve endings also known as?

Answer 21

The secondary endings or the flower spray endings

Question 22

Where do A gamma motor neurons connect?

Answer 22

ONLY the polar regions of the nuclear bag and nuclear chain fibers

Question 23

What does the contracting of the polar myofibrils in the muscle spindle cause?

Answer 23

A stretch of the spindle’s equatorial region (due to both ends of intrafusal muscle fibers being pulled)

Question 24

What does activation of the gamma motor neurons prevent while extrafusal muscle contracts?

Answer 24

Prevents the muscle spindle from becoming slack

Question 25

Why does the muscle spindle need to remain taught even during muscle contraction?

Answer 25

To maintain sensitivity so the sensory receptors can send information to the CNS

Question 26

True or false: Activation of A gamma axons causes activation of muscle contraction.

Answer 26

False; A gamma only sensitizes the equatorial region of the muscle spindle. There is not enough of a pull (or stretch) on the equatorial region to cause a muscle contraction

Question 27

The discharge of nerve action potentials at any constant or fixed muscle length

Answer 27

The static response

Question 28

With the static response, a greater length give you ________.

Answer 28

A greater frequency of action potentials

Question 29

What afferent neuron(s) have a static response?

Answer 29

Group Ia and Group II (primarily)

Question 30

The discharge of APs during the stretch or muscle length change.

Answer 30

The dynamic response

Question 31

What afferent neuron(s) are velocity sensitive?

Answer 31

Group Ia

Question 32

Static response signals of fixed length to the CNS: Longer muscle length ---> ______ Shorter muscle length ---> ______

Answer 32

Greater AP (impulse) frequency; Lower AP (impulse) frequency

Question 33

Dynamic Response signals of velocity of length change to CNS: Greater stretch velocity --> _____ Slower stretch velocity --> _____

Answer 33

Greater AP (impulse) frequency; Lower AP (impulse) frequency

Question 34

Physical properties innervated by _____ are low viscosity stretch sensitive equatorial region

Answer 34

Ia

Question 35

Physical properties innervated by _____ are high viscosity stretch resistant polar region

Answer 35

II

Question 36

Conduction properties of the axons of ____ are larger in diameter causing greater impulse conduction velocity with faster response.

Answer 36

Ia

Question 37

Conduction properties of the axons of ____ are smaller in diameter causing lower conduction velocity with slower response.

Answer 37

II

Question 38

A specialized proprioceptor that sends information to the CNS about muscle contraction (or shortening force) and muscle stretch (or lengthening force)

Answer 38

GTO

Question 39

GTO's are oriented in ____ to 15-20 extrafusal muscle fibers in the musculotendinous junction of skeletal muscle

Answer 39

Series

Question 40

The GTO is composed of a network of _______________ arranged in series with 15-20 extrafusal muscle fibers.

Answer 40

Small unmyelinated nerve fibers

Question 41

True or False: The nerve fibers of the GTO are enclosed in a capsule.

Answer 41

True

Question 42

The nerve fibers are branches of _______.

Answer 42

A single Ib myelinated primary afferent axon

Question 43

True or False: The GTO has no motor nerve connection or innervation.

Answer 43

True

Question 44

What stimulates the GTO?

Answer 44

Muscle tension developed during a muscle contraction

Question 45

GTOs send a ____ frequency of APs to the CNS during muscle contraction and a ______ frequency of APs during muscle stretch.

Answer 45

Greater; lower

Question 46

Do muscle spindles send action potentials during muscle contraction?

Answer 46

No, because they are slack