Lecture 6

Question 1

Alpha and gamma neurons are what kind of neurons?

Answer 1

Motor

Question 2

What is the difference between Golgi tendon organs and Muscle Spindles

Answer 2

Both are sensory organs
Muscle spindle- detect stretch in muscle
GTO- Detect stretch in tendon

Question 3

What are the joint kinesthetic receptors

Answer 3

Pacinian and ruffini corpusle

bare endings

Question 4

Muscle spindles are ______ muscle fibers

Answer 4

Intrafusal

Question 5

True or false: muscle spindles contract in their central region

Answer 5

False, the central region is non-contractile

Question 6

Type 2 sensory fibers go to what muscle spindles?

Answer 6

Nuclear chain and STATIC nuclear bag fibers

(not dynamic nuclear bag)

Question 7

Type 1a fibers go to what muscle spindles?

Answer 7

All 3

Nuclear chain, static, and dynamic nuclear bag

Question 8

Static gamma neurons innervate the contractile endings of what muscle spindles?

Answer 8

Static nuclear bag and nuclear chain

Question 9

Dynamic gamma neurons innervate the contractile endings of what muscle spindles?

Answer 9

dynamic nuclear bags

Question 10

True or false: Sarcomeres are found inside of intrafusal muscle fibers

Answer 10

False. only in extrafusal

Question 11

What do gamma motor neurons innervate?

Answer 11

The contractile ends of muscle spindles

slide says: “polar regions of intrafusal fibers”

Question 12

Small diameter Alpha motor neurons (also called lower motor neurons) innervate what?

Answer 12

Extrafusal skeletal muscle fibers

Question 13

Large diameter 1a and 2 fibers originate from the _____ region of muscle spindles

Answer 13

Central regions

Question 14

A typical muscle spindle contains ____ nuclear bag and ____ chain fibers

Answer 14

2-3 nuclear bag and 5 chain fibers

Question 15

Muscle spindles measure the velocity of stretch from phasic discharge of ____ fibers

Answer 15

1a

Question 16

Muscle spindles measure the steady state length of muscle from tonic discharge of _______ fibers

Answer 16

1a and 2

Question 17

1a’s have both ____ and _____ discharges

whereas 2’s only have ____ discharges

Answer 17

1a: Phasic and tonic

2: only tonic

Question 18

True or false: Muscle spindles fire even when muscle fibers are relaxing

Answer 18

True

Question 19

Muscle spindles regulate _____________ neurons via feedback mechanism/stretch reflex

Answer 19

alpha motor neurons

Question 20

Muscle spindles send input via sensory neurons to the spinal cord at the _________ horn and the spinal cord relays information to the muscle via alpha motor neurosn from the _______ horn

Answer 20

Dorsal horn (afferent)

Ventral horn (efferent)

Question 21

Gamma motor neurons control the ______ of the muscle spindles

Answer 21

Sensitivity

Question 22

Dynamic gamma motor neurons increase the dynamic sensitivity of…

Answer 22

1a fibers

Question 23

Static gamma motor neurons increase the tonic activity of….

Answer 23

Type 1a and 2

Note: also decreases the dynamic sensitivity of 1a

Question 24

When extrafusal fibers shorten the intrafusal fibers _______

Answer 24

Are slack, do not fire as much

Note: less stretch = less firing

Question 25

Without the sensory afferents of muscle spindles, the CNS cannot monitor information about....

Answer 25

Muscle length/position

Question 26

coactivation of gamma and alpha motor neurons ensure

Answer 26

appropriate length/tension relationship

Question 28

What causes reciprocal inhibitor? Golgi Tendon Organs OR Muscle Spindles

Answer 28

Muscle Spindles

Question 29

How does reciprocal inhibition work?

Answer 29

Muscle spindles of agonist (example:quads) send signal to spinal cord From the spinal cord a signal is sent that activates further contraction at the quads AND it sends a signal via inter neurons to inhibit contraction of the antagonist (example:hamstrings)

Question 30

True or false: reciprocal inhibition can occur voluntarily AND reflexively

Answer 30

True

Question 31

Where are golgi tendon organs found?

Answer 31

At the junction between muscle fibers and tendons

Question 32

What kind of neurons innervate the Golgi Tendon Organs?

Answer 32

1b fibers

Question 33

What do Golgi tendon organs do?

Answer 33

Autogenic inhibition or activation The respond to force/muscle tension at the junction between the muscle and its tendon They can either inhibit or activate the same muscle that they’re found in.

Question 34

True or false: both the Golgi tendons and the muscle spindles use *fast conducting* afferent nerves

Answer 34

True

Question 35

What is the ratio of muscles to motor neurons?

Answer 35

1:1