Spinal Cord Somatic Reflexes and Motor Control Quiz

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Which of the following is true about the reflex arc for spinal cord somatic reflexes?

Processing of information occurs before sensory info transmission.

Where are motor neurons located in the spinal cord?

Ventral (anterior) gray horn

What type of information do muscle spindles signal?

Muscle length & rate of change

Which type of motor neurons innervate the extrafusal muscle fibers?

Alpha motor neurons

What is the function of the sensory fibers (Ia) that terminate in the non-contractile region of the intrafusal fibers?

To detect changes in muscle length

What is the significance of the linkage between alpha and gamma motor neurons?

Enables the muscle spindle to signal length changes over the full range of muscle length

What is the function of the Golgi tendon organ?

To detect the force level generated by the muscle

Which type of reflex is the SCI Stretch reflex (myotatic reflex)?

Myotatic reflex

What is the purpose of the inverse myotatic stretch reflex?

Causes muscle relaxation of the agonist muscle before tendon damage occurs

What happens during the flexor reflex?

The extensor muscle relaxes and the flexor muscle contracts

What is the function of inhibitory interneurons in the reciprocal innervation (inhibition)?

Inhibit the activity of the motor neuron projecting to the flexor muscle

Which structure signals the amount of force being applied to a muscle?

Golgi tendon organ

What is the function of the muscle spindle?

Signals muscle length

Where are motor neurons located in the spinal cord?

Ventral (anterior) gray horn

What type of information do Golgi tendon organs signal?

Muscle tension

Which of the following is true about the reflex arc for spinal cord somatic reflexes?

It involves both sensory and motor neurons

What is the function of sensory fibers (Ia) that terminate in the non-contractile region of the intrafusal fibers?

Signal muscle spindle activation

Which neurons innervate the extrafusal muscle fibers?

Alpha motor neurons

What is the purpose of the inverse myotatic stretch reflex?

To prevent muscle damage from excessive force

What is the function of inhibitory interneurons in reciprocal innervation (inhibition)?

To inhibit antagonist muscle contraction

What is the significance of the linkage between alpha and gamma motor neurons?

To regulate muscle length

Which type of motor neurons innervate the intrafusal muscle fibers of the muscle spindle?

Gamma motor neurons

What is the function of the sensory fibers (Ia) that terminate in the non-contractile region of the intrafusal fibers?

To detect changes in muscle length

What is the role of gamma motor neurons in the muscle spindle?

To adjust the level of tension in the intrafusal fibers

Which type of gamma motor neurons modulate sensory information in a dynamic fashion?

Dynamic gamma motor neurons

What happens to the firing of the Ia sensory fiber when the alpha motor neuron alone is stimulated?

The firing stops

What happens to the firing of the Ia sensory fiber when both the alpha and gamma motor neurons are stimulated?

The firing increases

What is the function of the Golgi tendon organ?

To detect changes in muscle tension

What type of fibers innervate the Golgi tendon organ?

Ib fibers

What is the role of Ib afferent fibers in the autogenic inhibition reflex?

To activate inhibitory interneurons

What is the significance of the stretch reflex?

It helps maintain muscle tone

Which of the following is true about the myotatic stretch reflex?

The reflex includes a monosynaptic excitatory pathway from group Ia afferent fibers to alpha motor neurons

What is the purpose of reciprocal innervation in the myotatic stretch reflex?

To relax the flexor muscle

Which type of reflex is the flexor reflex?

Polysynaptic

What is the effect of the crossed extensor reflex?

The E muscle contracts and the F muscle relaxes on the opposite side of the stimulus

What happens when a reflex is initiated with a strong stimulus?

More spinal cord segments are recruited

What is the purpose of the Golgi tendon organ?

To control tendon tension of the activated muscle

What is the reflex arc for the myotatic stretch reflex?

Simultaneous activation of alpha motor neurons and inhibitory interneurons

What is the reflex arc for the inverse myotatic stretch reflex?

Afferent signals travel via type Ib sensory fibers to the spinal cord

Which type of motor neurons innervate the extrafusal muscle fibers?

Alpha motor neurons

What is the function of the sensory fibers (Ia) that terminate in the non-contractile region of the intrafusal fibers?

To detect changes in muscle length

What happens to the firing of the Ia sensory fiber when the alpha motor neuron alone is stimulated?

The Ia fiber stops firing

What is the purpose of reciprocal innervation in the myotatic stretch reflex?

To inhibit the antagonist muscle

What is the function of the Golgi tendon organ?

To detect changes in muscle tension

What is the effect of the crossed extensor reflex?

It causes the opposite limb to extend

What type of information do muscle spindles signal?

Changes in muscle length

What is the function of inhibitory interneurons in reciprocal innervation (inhibition)?

To inhibit the antagonist muscle

What is the significance of the linkage between alpha and gamma motor neurons?

It enables the muscle spindle to signal length changes over the full range of muscle length

What type of reflex is the SCI Stretch reflex (myotatic reflex)?

Monosynaptic

Which structure signals the length of a muscle and changes in the length of a muscle?

Muscle spindle

Where are motor neurons located in the spinal cord?

Ventral (anterior) gray horn

What is the function of inhibitory interneurons in the reciprocal innervation (inhibition)?

To inhibit the antagonist muscle

What is the role of gamma motor neurons in the muscle spindle?

To increase muscle spindle sensitivity

Which type of reflex is the flexor reflex?

Polysynaptic reflex

What is the purpose of reciprocal innervation in the myotatic stretch reflex?

To excite the antagonist muscle

What type of reflex is the SCI Stretch reflex (myotatic reflex)?

Monosynaptic reflex

What happens when a reflex is initiated with a strong stimulus?

The reflex response is stronger

What is the effect of the crossed extensor reflex?

To flex the contralateral limb

What is the function of sensory fibers (Ia) that terminate in the non-contractile region of the intrafusal fibers?

To excite the muscle spindle

Which of the following is true about the myotatic stretch reflex?

It is a monosynaptic reflex

What is the function of inhibitory interneurons in reciprocal innervation (inhibition)?

To relax the antagonist muscle

What is the effect of the crossed extensor reflex?

It causes the opposite leg to flex

What type of information do muscle spindles signal?

Muscle length and change of muscle length

What is the purpose of the inverse myotatic stretch reflex?

To prevent exhaustive tension in the agonist muscle

What happens during the flexor reflex?

The extensor muscle relaxes and the flexor muscle contracts

What is the reflex arc for the myotatic stretch reflex?

Alteration of muscle length activates muscle spindles

What is the role of gamma motor neurons in the muscle spindle?

To adjust the sensitivity of the muscle spindle

What happens when a reflex is initiated with a strong stimulus?

More spinal cord segments are recruited

What happens to the firing of the Ia sensory fiber when the alpha motor neuron alone is stimulated?

The firing of the Ia sensory fiber increases

Study Notes

Reflex Arc and Motor Neurons

  • Motor neurons are located in the ventral horn of the spinal cord.
  • Alpha motor neurons innervate extrafusal muscle fibers.
  • Gamma motor neurons innervate intrafusal muscle fibers of the muscle spindle.

Muscle Spindles

  • Muscle spindles signal the length of a muscle and changes in the length of a muscle.
  • Sensory fibers (Ia) that terminate in the non-contractile region of the intrafusal fibers signal the length of a muscle.
  • The role of gamma motor neurons in the muscle spindle is to modulate sensory information in a dynamic fashion.

Reflexes

  • The SCI Stretch reflex (myotatic reflex) is a type of reflex that responds to muscle stretch.
  • The purpose of the inverse myotatic stretch reflex is to reduce muscle tone.
  • The flexor reflex is a withdrawal reflex that occurs when a stimulus is applied to a limb.
  • The effect of the crossed extensor reflex is to contract the extensor muscles of the opposite limb.

Golgi Tendon Organ

  • The Golgi tendon organ signals the amount of force being applied to a muscle.
  • Ib afferent fibers innervate the Golgi tendon organ.
  • The role of Ib afferent fibers in the autogenic inhibition reflex is to reduce muscle force.

Inhibitory Interneurons

  • Inhibitory interneurons are involved in reciprocal innervation (inhibition), which allows for coordinated movement.
  • The function of inhibitory interneurons in reciprocal innervation (inhibition) is to reduce muscle tone.

Alpha and Gamma Motor Neurons

  • The significance of the linkage between alpha and gamma motor neurons is that they work together to control muscle tone and length.
  • When the alpha motor neuron alone is stimulated, the firing of the Ia sensory fiber increases.
  • When both the alpha and gamma motor neurons are stimulated, the firing of the Ia sensory fiber remains constant.

Test your knowledge on spinal cord somatic reflexes and motor control with this quiz. Learn about the reflex arc, sensory information transmission, motor neuron activation, and more. Explore the basic neuronal circuit for motor control and muscle receptors.

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