Nsp: Muscle Innervation And Reflexes - Blair

Front 1

Are axial and girdle muscles medial or lateral SC?

Are distal limbs/extremities medial or lateral SC?

Back 1

Axial/Girdle: Medial

Distal Limbs/Extremities: Lateral

Front 2

Are flexor motorneurons ventral or dorsal SC?

Are extensor motorneurons ventral or dorsal SC?

Back 2

Flexors - Dorsal

Extenstors - Ventral

Front 3

Which motoneurons innervate the force generating (extrafusal) muscle fibers?

Back 3

alpha-motoneurons

Front 4

Which motoneurons innervate the non-force generating (intrafusal) muscle fibers within the muscle spindle?

Back 4

gamma-motoneurons

Front 5

all the motoneurons the innervate a muscle

Back 5

motoneuron pool

Front 6

a motoneuron and all its muscle fibers

Back 6

motor unit

Front 7

all of the muscles innervated by a single nerve root

Back 7

mytome

Front 8

What two events control the force of contraction?

Back 8

1. Recruitment of motor units (first)

2. Frequency of action potentials

Front 9

What is the size principle in regards to Recruitment?

Back 9

smaller motoneurons are recruited first

Why? Smaller motoneurons are more excitable b/c they have a higher Rin

Rin=Rm/A

Front 10

Which motor units are resistant to fatigue?

Back 10

Slow motor units: Red/Type I

Fast motor units are fatigue-able: white Type II

Front 11

Lesions to nerve roots are called what?

Back 11

radiculopathies

Front 12

Which spinal nerve has no dorsal root?

Back 12

C1

Front 13

What spinal nerve comes out between C5 and C6?

Back 13

C6

Front 14

What spinal nerve comes out between C7 and T1?

Back 14

C8

Front 15

What spinal nerve comes out between T10 and T11?

Back 15

T10

Front 16

If the disc between C3 and C4 herniates which spinal nerve is affected?

Back 16

C4

In the cervical the spinal nerve the exits the same foramen will be affected. I.E. C4 comes out between C3 and C4.

Front 17

If the disc between L3 and L4 hearniates, which spinal nerve is affected?

Back 17

L4

In the lumbar region, the spinal root in the next lowest foramen is affected. I.E. Between L3 and L4, the spinal nerve L3 comes out, so the foramen below this one is affected and thus L4 is in that foramen.

Front 18

Where are most of the muscle spindles located?

Back 18

close to the tendons

Front 19

What do Ia fibers signal ?

Back 19

both rate of change (bag 1) and magnitude of length (bag2/chain)

Front 20

What do group II fibers signal?

Back 20

magnitude and length (bag 2 /chain)

NOT rate of change in length

Front 21

True or false for each statement:

1. A spindle receives innervation from a single Ia fiber.

2. A spindle receives innervation from a single II fiber.

3. A spindle receives innervation from multiple gamma-motoneurons.

4. A spindle receives innervation from multiple Beta-motoneurons.

Back 21

all True

dynamic gamma-motoneurons innervate Bag1 fibers. Static gammas innervate a mixture of Bag 2 & chain.

Dynamic B-motoneurons innervate Bag1 fibers. Static B-motoneurons innervate LONG chain fibers only. (Both types have branches that innervate extrafusal fibers)

Front 22

Stretching the intrafusal sensory fibers results in what?

Back 22

increase in the frequency of action potentials in the sensory neurons

Front 23

Choose between phasic, tonic, or both:

1. Group Ia sensory fibers

2. Group II sensory fibers

Back 23

Ia - both (rate of change and magnitude of length.)

II - only tonic (magnitude of length)

Front 24

gamma motorneurons do what?

Back 24

alter the sensitivity (or gain) of the spindle by increasing or decreasing the amount of stretch on the center region of the spindle

Front 25

Are GTO's in parallel or series with muscle fibers?

Back 25

series

Front 26

What fibers transmit tension information/GTO?

Back 26

Ib fibers

Front 27

While a Ia spindle fiber is excited w/ passive stretch and inhibited w/ contraction/shortening a GTO Ib fiver is ________ with passive stretch and ________ with contraction and shortening.

Back 27

While a Ia spindle fiber is excited w/ passive stretch and inhibited w/ contraction/shortening a GTO Ib fiber is EXCITED with passive stretch and EXCITED with contraction and shortening.

Front 28

How is the stretch reflex elicited?

Back 28

by tapping on a tendon attached to a muscle

Front 29

Does tendon tapping active Ib fibers from Golgi tendon organs?

Back 29

NO

Front 30

What is the primary function of stretch reflexes?

Back 30

maintain appropriate lengths of muscles in different postures

Front 31

What stretch reflex involves C5-6

Back 31

Biceps

Front 32

What stretch reflex involves C7-8

Back 32

Triceps

Front 33

What stretch reflex involves L3-4

Back 33

Knee

Front 34

What stretch reflex involves S1-2?

Back 34

ankle

Front 35

What term describes oscillations in muscle contraction in which the muscle alternatively contracts and relaxes rapidly.

Back 35

Clonus

observed in hyperreflexive states and is causes by sequential stretch reflexes

Front 36

True or False

Alpha and gamma motoneurons are activated together during most normal movements

Back 36

TRUE

Front 37

Which motoneurons have the ability to adjust contraction DURING a movement?

Back 37

gamma motoneurons

Front 38

What fibers are involved in the tendon reflex?

Back 38

Ib fibers

Front 39

The flexor reflex is elicited by what?

Back 39

nociceptive stiumulus - activates Adelta and C fibers NOT afferent muscle fibers

excited neurons innvervating flexor alpha motoneurons and inhibits extensors. Therefore the limb flexes away from the stimulus (protective)

Front 40

What is the purpose of the crossed extensor reflex?

Back 40

To support a limb during withdrawal

Front 41

What are Renshaw cells?

Back 41

a unique type of inhibitory interneuron

Front 42

What excites a Renshaw cell and then what does it do?

Back 42

collateral axons of alpha-motoneurons excites Renshaw cells.

The Renshaw cell inhibits the alpha-motoneuron that excited it and may inhibit all homonymous alpha-motoneurons to the same muscle.

Front 43

In addition to alpha-motoneurons, what else gives input to Renshaw cells?

Back 43

descending pathways from the brain

purpose: can inhbit muscles that are not needed in the forthcoming movement and reduce inhibition to muscles that will be used.