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Chapter 12. Reflex & Voluntary Control of Posture & Movement

A 48-year-old man was undergoing a thorough neurological exam after falling from a construction platform. The test included an evaluation of his deep tendon reflex. What are the elements of the deep tendon reflex?

A. Golgi tendon organ, group Ib afferent fibers, spinal inhibitory interneuron, contralateral α-motor neuron, and extrafusal fibers of the skeletal muscle

B. Golgi tendon organ, group II afferent fibers, spinal inhibitory interneuron, ipsilateral α-motor neuron, and intrafusal fibers of the skeletal muscle

C. Group Ia sensory fibers originating in the contractile portion of the intrafusal fibers of the muscle spindle, spinal dorsal horn neuron, ipsilateral α-motor neuron, and extrafusal fibers of the skeletal muscle

D. Group Ia sensory fibers originating in the central portion of the intrafusal fibers of the muscle spindle, ipsilateral α-motor neuron, and extrafusal fibers of the skeletal muscle

E. Group II sensory fibers originating in the contractile portion of the intrafusal fibers of the muscle spindle, spinal inhibitory interneuron, ipsilateral α-motor neuron, and extrafusal fibers of the skeletal muscle

When dynamic γ-motor neurons are activated at the same time as α-motor neurons to muscle,

A. prompt inhibition of discharge in spindle Ia afferents takes place.

B. clonus is likely to occur.

C. the muscle will not contract.

D. the number of impulses in spindle Ia afferents is smaller than when α discharge alone is increased.

E. the number of impulses in spindle Ia afferents is greater than when α discharge alone is increased.

The inverse stretch reflex

A. occurs when Ia spindle afferents are inhibited.

B. is a monosynaptic reflex initiated by activation of the Golgi tendon organ.

C. is a disynaptic reflex with a single interneuron inserted between the afferent and efferent limbs.

D. is a polysynaptic reflex with many interneurons inserted between the afferent and efferent limbs.

E. uses type II afferent fibers from the Golgi tendon organ.

Withdrawal reflexes are

A. initiated by innocuous stimulation of the skin.

B. can lead to the appearance of clonus.

C. prolonged if ...

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