Muscle Sensory Control Flashcards

1
Q

What are the two types of muscle receptors?

A

Muscle spindles

Golgi tendon organs

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2
Q

What is the function of muscle spindles?

A

Signal joint position and movement by monitoring muscle length

Signal movement velocity

Located within the muscle

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3
Q

What is kinesthesia?

A

Conscious sense of body position and movement that depends upon signals from muscle receptors

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4
Q

What is the stretch reflex?

A

Stretch of muscle spindles that causes the contraction of a muscle (e.g. gastrocnemius)

Does not require conscious awareness

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5
Q

What type of motor neurons innervate muscle spindles?

A

Gamma motor neurons

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6
Q

What are golgi tendon organs?

A

Located in muscle tendons or connective tissue attachments

Sensitive to tension in the tendon and signals force

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7
Q

What type of neuron is responsible for skeletal muscle contraction?

A

Alpha motor neurons (Lower motor neurons)

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8
Q

What is muscle tonus?

A

The muscle tension at rest, due to activities in alpha motor neurons at rest

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9
Q

Where is the density of muscle spindles highest?

A

Highest in muscles that are used in fine control

E.g. muscles involved in finger and eye movements

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10
Q

How are muscle spindles different from normal muscle cells?

A

Nuclei are in the middle

Middle region does not contract (no contractile filaments), location of sensory innervation

The polar regions (ends) have contractile filaments and can contract, location of motor innervation

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11
Q

Describe gamma motor neurons

A

Smaller that alpha motor neurons

About 30% of all axons in ventral roots are gamma motor neurons

Firing contracts muscle spindle, but does not generate much force at the muscle tendon

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12
Q

What are Gamma dynamic motor neurons?

A

Innervate fast contracting muscle cells

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13
Q

What are Gamma static motor neurons?

A

Innervate slow contracting muscle cells

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14
Q

What are sensory Ia neurons?

A

1

per spindle; innervates all muscle cells

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15
Q

What are sensory II neurons?

A

1-5 per spindle; innervates only slow contracting muscle cells

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16
Q

How does a tendon tap cause a reflex?

A

Produces a brief fast stretch of the muscle, which in turn activates all spindle sensory neurons in the muscle

17
Q

What do group II fibers encode about stretch?

A

Only encode magnitude of change in length

i.e. how long is the muscle

18
Q

What do group Ia fibers encode about stretch?

A

Encode velocity of stretch and length

i.e. how fast is stretch

19
Q

What is the function of gamma motor neurons?

A

Adjust spindle length to muscle length; reset sensitivity

20
Q

What type of sensory neurons innervate golgi tendon organs?

A

Large, Type Ib sensory neurons

21
Q

What type of contraction will cause a large discharge in the golgi tendon organ?

A

Isometric contractions