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SF1 - Test 2 > 4 - Zill - Muscle Sensory Control > Flashcards

4 - Zill - Muscle Sensory Control Flashcards

1
Q

Muscle Spindles

A

Signal muscle length, movement, velocity

Have both sensory and motor innervation (gamma motor neurons)

Sensory sensitive to muscle stretch or

CHANGES IN LENGTH

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2
Q

Golgi Tendon Organs

A

Signal force

Located in muscle tendon or connective tissue attachments

Sensitive to tension in tendon

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3
Q

Dorsal Columns

A

Contain axon branches of sensory neurons that carry fine/discriminative touch, conscious proprioception, and vibration

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4
Q

Lateral and Anterior Columns of White Matter

A

Contains spinothalamic tracts of neurons that receive sensory inputs about crude touch, pain, and temperature

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5
Q

stroke

A

Cerebrovascular accident, interupt or block blood flow to brain (either block or rupture vessel)

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6
Q

Kinesthesia

A

Conscious sense of body position, depends upon signals from muscle receptors

Signals transmitted in pathways that reach brain (thalamus and cortex)

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7
Q

What do signals from muscle sensory receptors contribute to?

A

Conscious sense of body position

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8
Q

What does the stretch (“Deep Tendon”) of muscle spindles evoke?

How do these occur?

A

Stretch Reflex in CNS, producing contraction of muscle

Automatically–do NOT require conscious awareness

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9
Q

Guillain Barre Syndrome

A

Loss of axons in peripheral nerves–demyelination of large fibers, lose proprioception

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10
Q

Receptors:

Exteroception

Proprioception

A

Exteroception - detection of outside world (touch, temperature, etc)

Proprioception - detection of position and movement of body intself

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11
Q

Sense Organs:

Proprioceptors

A

Proprioceptors - sense organs that detect position and movement of body itself

Ex: Muscle spindles and golgi tendon organs

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12
Q

What causes skeletal muscles to contract?

A

Alpha motor neurons (lower motor neurons) fire action potentials

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13
Q

What occurs to muscle upon contraction?

A

Muscle length shortens, generates force

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14
Q

How does the nervous system calculate limb position?

A

Know length, calculate limb position, angles, and velocity. Can calculate rate of limb movement.

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15
Q

What detects movement and position?

Force?

A

Muscle spindles = movement/position

Tendon organs = force

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16
Q

What occurs to muscle spindles and golgi tendon organs during isometric contractions?

A

No movement = no change in muscle spindles

Increase force detected by golgi tendon organs

17
Q

Muscle Tonus

How do you test tonus?

How do you test strength?

A

Muscle tension at rest, due to activities (background firing) in alpha motor neurons at rest

Slow stretch of relaxed muscle

Resist stretch in isometric fashion–no increase in muscle spindles, but tendon organs sense force

18
Q

Clinical presentation of changes in tonus?

A

Tonus increased in Upper Motor Neuron Disorders

19
Q

How are muscle spindles oriented to regular muscle cells?

What defines density?

Where is it highest?

A

Parallel

Density - number of spindles/number of regular muscle cells.

Highest in muscles used for fine control–hands, eyes

20
Q

What occurs when muscle are stretched?

A

Muscle spindles are stretched due to parallel orientation

21
Q

How are spindle muscle cells innervated?

A

Sensory neurons (cell bodies in dorsal root ganglia)

and

Motor neurons (cell bodies in ventral horn)

22
Q

Intrafusal Cell

A

Sindle muscle cells

23
Q

Polar Regions

A

Home of contraction filaments (can contract)

location of motor innervation

24
Q

Equatorial Region

A

Nuclei here

Location of sensory nerve endings

25
Q

How do types of intrafusal muscle cells differ?

A

Fast contracting one spindle/fiber, gamma dynamic motor neuron

Slow contracting multiple spindles/fiber , gamma static motor neuron

26
Q

Gamma Motor Neurons

Does one possess voluntary control of these?

A

Innervate only spindle muscle cells (not regular muscle cells)

Firing causes spindle muscle to contract but does not generate much force at the muscle tendon (that occurs through Alpha motor neurons/reflexes)

- -

No voluntary control of Gamma Motor Neurons

27
Q

How does contraction of regular muscle cells occur?

A

Alpha Motor Neurons and Reflexes

28
Q

Sensory Innervation:

Ia

II

A

Ia = 1 per spindle, innervates all muscle cells

II = 1-5 per spindle, innervates ONLY slow contracting muscle cells

29
Q

What type of motor neurons innervate fast contracting muscle cells?

What type of sensory neurons do these receive?

A

Gamma Dynamic Motor Neurons

Only Ia Sensory Neurons

30
Q

What type of motor neurons innervate slow contracting muscle cells?

What type of sensory neurons do these receive?

A

Gamma Static

Ia, II

31
Q

What does a Tendon Tap activate?

A

Activate all muscle spindles (like a stretch), does NOT activate Golgi Tendon Organs

Activates all spindle sensory neurons (Ia / II)

32
Q

What does group Ia and II encode?

A

Ia - Velocity of Stretch (how fast is stretch)

II - Magnitude of change of length (how long is muscle)

33
Q

Sensing which (group II or Ia) will allow rapid change to body position?

A

Group Ia, length and velocity

34
Q

What sets spingle length to match muscle length?

How are sensory signals still set?

A

Gamma Motor Neurons

The muscle spindles are reset so they can still signal stretch

35
Q

What occurs to Gamma Dynamic motor neuron activity?

What is the result of this?

A

It is increased in anticipation of pertubations

Selectively enhances 1a sensory neurons (not enhance group II) and increases discharge at start of perturbation (dynamic phase)

36
Q

Why must patients relax before neurological tests?

A

Ia can be enhanced by Gamma Dynamic Motor Neurons subconsciously (nervous) in anticipation of perturbations

37
Q

Golgi Tendon Organs end point

What type of neuron are these?

A

Large (Type 1b) sensory neurons end in muscle tendon or connective tissue attachment (myotendinous junction)

38
Q

How would you get a maximum discharge in a Golgi Tendon Organ?

A

Isometric Contraction

No discharge from muscle spindles

39
Q
A

SF1 - Test 2 (13 decks)

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