Chapter 6 Workbook Questions Flashcards

1
Q

How is unconscious sensory information used by the nervous system?

A

Used for the control of automatic adjustments during postural and movement control.

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2
Q

Where are the cell bodies of most peripheral sensory neurons located?

A

In the dorsal root ganglia or cranial nerve ganglia.

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3
Q

List the classifications of peripheral sensory axons from the largest to the smallest diameter.

A

From the largest to the smallest diameter, the peripheral sensory axons are Ia, Ib, II, Aδ, and C.

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4
Q

What is a nociceptor?

A

Receptor that responds to stimuli that damage or threaten to damage tissue.

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5
Q

What type of afferent fibers conveys information from free nerve endings?

A

The Aδ and C axonal afferents convey sensory information from free nerve endings.

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6
Q

What is the function of the Primary endings (part of the muscle spindle)?

A

Respond to quick stretches of the central region of intrafusal fibers.

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7
Q

What is the function of the Nuclear bag fibers (part of the muscle spindle)?

A

Specialized muscle fibers with noncontractile central regions whose nuclei are arranged in a clump.

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8
Q

What is the function of the Secondary endings (part of the muscle spindle)?

A

Respond to tonic stretch of the central region of intrafusal fibers.

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9
Q

What is the function of the Gamma efferents (part of the muscle spindle)?

A

Motor neurons that innervate the contractile ends of intrafusal fibers.

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10
Q

What is the function of the Nuclear chain fibers (part of the muscle spindle)?

A

Specialized muscle fibers with noncontractile central regions whose nuclei are arranged in single file.

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11
Q

Pain, temperature, itch, or tickle What type of axon conveys this information?

A

Aδ or C

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12
Q

Touch, vibration, skin stretch, or pressure What type of axon conveys this information?

A

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13
Q

Maintained muscle stretch or joint movement What type of axon conveys this information?

A

II

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14
Q

Tendon or ligament tension What type of axon conveys this information?

A

Ib

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15
Q

Quick stretch information from the muscle spindle What type of axon conveys this information?

A

Ia

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16
Q

Is high-fidelity, discriminative awareness a function of the conscious relay pathways or divergent pathways?

A

Conscious relay pathways convey sensory information to the primary sensory cortex for high-fidelity, discriminative awareness of the location and nature of the stimulus.

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17
Q

Which of the spinocerebellar tracts function as internal feedback tracts?

A

The anterior spinocerebellar and rostral spinocerebellar tracts provide internal feedback from interneurons located between the descending motor tracts and the alpha motor neurons.

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18
Q

What is the function of the first-order neuron in a sensory pathway?

A

The first-order neuron conducts an electrical potential in response to stimulation of a peripheral receptor. The first-order neuron thereby conveys information from the peripheral receptor to a second-order neuron within the central nervous system (CNS).

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19
Q

Conveys information from the face to the pons. Which neuron for the discriminative touch/conscious proprioception pathway provides this information?

A

Trigeminal nerve neuron

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20
Q

Conveys information from the medulla to the thalamus. Which neuron for the discriminative touch/conscious proprioception pathway provides this information?

A

Second-order neuron

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21
Q

Conveys information from receptors in the limbs and trunk to the medulla. Which neuron for the discriminative touch/conscious proprioception pathway provides this information?

A

Peripheral/dorsal column neuron

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22
Q

Conveys information from the thalamus to the cerebral cortex. Which neuron for the discriminative touch/conscious proprioception pathway provides this information?

A

Third-order neuron

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23
Q

Spinal axons conveying a signal for conscious somatosensation from the upper limb ascend in which of the following?

A. Ventral horn

B. Fasciculus gracilis

C. Fasciculus cuneatus

D. Internal arcuate fibers

E. Medial lemniscus

A

C: Conscious somatosensory information from peripheral receptors is conveyed to the dorsal root and ascends through the ipsilateral dorsal column. Axons from the lower limb ascend in the medial dorsal column, called the fasciculus gracilis. Axons from the upper extremity ascend in the lateral dorsal column, called the fasciculus cuneatus.

24
Q

Cell bodies of second-order neurons conveying a signal for conscious proprioceptive information from the lower limb are located in which of the following?

A. Dorsal root ganglion

B. Fasciculus cuneatus

C. Somatosensory cerebral cortex

D. Nucleus gracilis

E. Medial lemniscus

A

D: First-order neurons conveying conscious proprioceptive input enter the dorsal root, with cell bodies located in the dorsal root ganglion. First-order neurons from the lower limb synapse with second-order neurons whose cell bodies are located in the nucleus gracilis of the medulla.

25
Q

The ventral posterolateral (VPL) nucleus of the thalamus is the site of synapse for:

A. First-order neurons of the dorsal column/medial lemniscus system

B. Second-order neurons with their cell bodies in the nucleus cuneatus and/or nucleus gracilis

C. Third-order neurons with their cell bodies in the spinal nucleus of the trigeminal cranial nerve

D. Second-order neurons with their cell bodies in the nucleus dorsalis (Clarke’s nucleus)

E. Third-order neuron with their cell body the lateral cuneate nucleus

A

B: Second-order neurons with their cell bodies located in the nucleus gracilis or nucleus cuneatus, cross the midline as the internal arcuate fibers and ascend to the thalamus as the medial lemniscus. These fibers then synapse with third-order neurons in the VPL nucleus of the thalamus.

26
Q

Rapidly turning the eyes and head toward a painful stimulus is a function of which one of the following tracts?

A. Trigeminoreticulolimbic

B. Spinoreticular

C. Spinomesencephalic

D. Trigeminospinothalamic

E. Dorsal column medial lemniscus

A

C: The spinomesencephalic tract carries nociceptive information to the superior colliculus and periaqueductal gray matter, producing a rapid turning of the eyes and head toward the source of the noxious input.

27
Q

Which of the following statements is true about the homunculus for the somatosensory cortex?

A. The homunculus was developed by experimentally recording electrical potentials from cells in the somatosensory cortex during stimulation of various parts of the body.

B. The area of the homunculus that represents the foot is adjacent to the area for the hand.

C. The proportions of the homunculus are the same as the proportions of the physical body.

D. Somatotopic organization is only found in cellular organization of the somatosensory cortex.

E. The area of the homunculus that represents the torso is adjacent to the area for the face.

A

A: The homunculus represents the size of the area of primary sensory cortex devoted to specific parts of the body. This sensory map was developed by recording the electrical potentials of neurons in the sensory cortex when stimulating various areas of the body. Increased cortical representation corresponds to a higher degree of receptors and fine-motor control required by the body area. This somatotopic organization is maintained throughout the second- and third-order neurons.

28
Q

Which of the following is a function of the primary somatosensory cortex?

A. Discrimination of the texture of an object

B. Discrimination of the shape of an object

C. Stereognosis

D. Both A and B

E. A, B, and C

A

D: The primary somatosensory cortex allows for the discrimination of the size, texture, and shape of objects, whereas the thalamus provides stereognosis and memory of the tactile and spatial environment.

29
Q

A lesion to which one of the following regions would result in crossed analgesia?

A. Dorsal horn of the spinal cord

B. Peripheral nerves

C. Medulla or lower pon

D. Thalamus

E. Cortex

A

C: A lesion of the lower pons and medulla can produce crossed analgesia because axons conveying fast pain information from the face descend ipsilaterally near the spinothalamic tract, which carries pain information from the contralateral side of the body.

30
Q

What tract carries Discrimitive pain information?

A

Spinothalamic

31
Q

Where is the termination of the first degree neuron of the spinothalamic tract?

A

Dorsal horn lamina I, II, and/or V

32
Q

Where is the termination of the second degree neuron of the spinothalamic tract?

A

VPL nucleus of the thalamus

33
Q

Where is the termination of the third degree neuron or final group of neurons of the spinothalamic tract?

A

Primary sensory cortex

34
Q

What tract carries nonlocalized pain information that reaches consciousness?

A

Spinolimbic

35
Q

Where is the termination of the first degree neuron of the spinolimbic tract?

A

Dorsal horn lamina I, II, and/or V

36
Q

Where is the termination of the second degree neuron of the spinolimbic tract?

A

Midline and intralaminar nuclei of the thalamus

37
Q

Where is the termination of the third degree neuron or final group of neurons of the spinolimbicc tract?

A

Areas of cerebral cortex involved in emotions, personality, sensory integration, and movement

38
Q

What tract carries nonlocalized, unconscious pain information?

A

Spinomesencephalic or spinoreticular

39
Q

Where is the termination of the first degree neuron of the Spinomesencephalic or spinoreticular?

A

Dorsal horn lamina I, II, and/or V

40
Q

Where is the termination of the second degree neuron of the Spinomesencephalic or spinoreticular tract?

A

Superior colliculus, periaqueductal gray

41
Q

Name the two high-fidelity pathways that convey unconscious proprioceptive information to the cerebellar cortex.

A

Posterior spinocerebellar and cuneocerebellar pathways

42
Q

Posterior spinocerebellar and cuneocerebellar pathways

A

Anterior spinocerebellar and rostral spinocerebellar tracts

43
Q

Label the Dermatomes and peripheral nerve innervation areas indicated in the following

A
44
Q

What are the three types of somatosensory receptors?

A

mechanical, chemical, and temperature.

45
Q

To what do primary and secondary sensory endings in muscle spindles respond?

A

Primary endings respond to stretch of muscle and to the rate of muscle stretch. Secondary endings respond only to stretch.

46
Q

How is the sensitivity of sensory endings in a muscle spindle maintained when the muscle is shortened?

A

Firing of gamma-motor neurons causes contraction of the ends of the intrafusal fibers. The contraction maintains the stretch of the central region of the intrafusal fibers so that the sensory endings are able to respond to stretch of the muscle.

47
Q

What type of information is transmitted by large diameter type Ia and Ib axons?

A

Muscle stretch information from primary endings in muscle spindles, tension in tendons from Golgi tendon organs, and tension in ligaments from ligament receptors are transmitted by large-diameter Ia and Ib axons.

48
Q

What classes of axons convey nociceptive and temperature information?

A

A and C axons convey nociceptive and temperature information.

49
Q

What are the 3 types of pathways that convey information to the brain?

A

The types of pathways that convey information to the brain are conscious relay, divergent, and unconscious relay.

50
Q

High-Fidelity, comatotopically arranged somatosensory information is conveyed to what area of the cerebral cortex?

A

High-fidelity, somatotopically arranged information is conveyed to the primary sensory cortex, located in the postcentral gyrus.

51
Q

Neural signals that are interpreted as dull, aching pain travel in what pathway?

A
  1. Neural signals that are interpreted as dull, aching pain travel in the spinolimbic tract; spinomesencephalic and spinoreticular tract information does not reach conscious awareness.
52
Q

What are the functions of the spinoreticular, spinomesencephalic, and spinolimbic pathways?

A

The spinoreticular pathway conveys nociceptive information from the spinal cord to the reticular formation. The spinomesencephalic pathway conveys nociceptive information to the superior colliculus and periaqueductal gray matter in the midbrain. The spinolimbic pathway transmits slow pain information to the medial and intralaminar nuclei in the thalamus; the neurons from these thalamic nuclei project to the anterior cingulate cortex, insula, amygdala, and dorsolateral prefrontal cortex.

53
Q

All of the unconscious relay tracts end in what part of the brain?

A

The unconscious relay tracts end in the cerebellum.

54
Q

Where do synapses occur between neurons conveying discriminant touch information from the left lower limb?

A

Synapses between neurons conveying discriminative touch information occur in the left nucleus gracilis in the medulla, right VPL nucleus in the thalamus, and primary somatosensory cortex.

55
Q

Where do synapses occur between neurons conveying discrimitive pain information from the left lower limb?

A

Synapses between neurons conveying discriminative pain information occur in the left dorsal horn of spinal cord, the right VPL nucleus in the thalamus, and the primary somatosensory cortex.

56
Q

Name the tracts that relay unconscious proprioceptive information to the cerebellum. Name the tracts that provide unconscious information about activity in spinal interneurons and descending motor commands

A

Posterior spinocerebellar and cuneocerebellar tracts convey unconscious proprioceptive information. The anterior spinocerebellar and rostrospinocerebellar tracts convey information about activity in spinal interneurons, and about descending motor commands.