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Questions and Answers
For a sensory nerve fiber that is connected to a Pacinian corpuscle located on the palmar surface of the right hand, the synaptic connection with the next neuron in the appropriate sensory pathway is in which of the following?
For a sensory nerve fiber that is connected to a free nerve ending located on the left hand, the synaptic connection with the next neuron in the appropriate sensory pathway is in which of the following?
The second neuron in the appropriate sensory pathway that connects a Meissner corpuscle in the left palm to the somatosensory cortex travels in the:
The second neuron in the appropriate sensory pathway that connects a free nerve ending in the left thumb to the somatosensory cortex travels in the:
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During the physical examination of a patient with a spinal injury at C7, two-point discrimination (fine touch) would:
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On which side of a patient with a spinal injury at C5 that transected the left half of the spinal cord would you expect pain and temperature sensations to be absent?
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On which side of a patient with a spinal injury at C7 that transected the left half of the spinal cord would you expect vibration sense to be absent?
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On which side of a patient with a spinal injury at C7 that transected the left half of the spinal cord would the position sensation (proprioception) be absent?
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The loss of fine touch and vibration sense in both the left arm and leg involved which of the following nerve tracts in the patient?
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The loss of pain and temperature sense in the right arm and leg involved which of the following nerve tracts in this patient?
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One can rule out a lesion in which of the following areas of the nervous system for this patient?
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Which of the following is the most likely location of the injury to the nervous system in this patient?
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Which of the following areas of the body has the greatest area of representation in the primary somatosensory cortex?
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Which of the following nerve structures carries axons from the dorsal column nuclei to the thalamus?
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A progressive rise in receptor potential (becomes less negative) of a typical mechanoreceptor is most likely to have which of the following effects on the frequency of action potentials in the axon from that mechanoreceptor?
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Which of the following sensory receptors is most likely to have the highest rate of adaptation?
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The third afferent neuron from a typical mechanoreceptor is most likely to terminate in which of the following structures?
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Which of the following best describes the number of neurons in series from a typical sensory receptor to the somatosensory cortex?
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Which of the following structures has the greatest area of representation in the somatosensory cortex?
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Which of the following serves to improve the two-point discrimination threshold in the fingers of a typical human being?
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All the following somatic sensations are transmitted in the anterolateral system except one. Which one is the exception?
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All the following somatic sensations are transmitted in the dorsal column-medial lemniscal system except one. Which one is the exception?
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Study Notes
Sensory Pathways
- Sensory nerve fibers from the right hand connect to the right dorsal column nucleus.
- Sensory nerve fibers from the left hand connect to the dorsal horn of the left side of the spinal cord.
- The second neuron in the sensory pathway for a Meissner corpuscle in the left palm travels in the contralateral medial lemniscus.
- The second neuron in the sensory pathway for a free nerve ending in the left thumb travels in the contralateral anterolateral column.
- Two-point discrimination (fine touch) is absent on the right side of the body after a spinal cord transection on the right side.
Somatosensory Deficits
- Pain and temperature sensations are absent on the right side of the body after a left-sided spinal cord transection.
- Vibration sense is absent on the left side of the body after a left-sided spinal cord transection.
- Position sensation (proprioception) is absent on the left side of the body after a left-sided spinal cord transection.
- Loss of fine touch and vibration sense in both the left arm and leg indicates involvement of the dorsal column system.
- Loss of pain and temperature sense in the right arm and leg indicates involvement of the anterolateral system.
- Sensory deficits in both arms and legs point to a lesion in the spinal cord, brain stem or peripheral nerves but not the cortex.
- The most likely location of the injury is the left side of the cervical spinal cord.
Somatosensory Cortex
- The face has the greatest area of representation in the primary somatosensory cortex.
- Axons from the dorsal column nuclei travel to the thalamus via the medial lemniscus.
- A progressive rise in receptor potential in a mechanoreceptor leads to a proportional increase in the frequency of action potentials.
- Pacinian corpuscles have the highest rate of adaptation among the sensory receptors.
- The third afferent neuron from a mechanoreceptor terminates in layer IV of the primary somatosensory cortex.
- The sensory pathway from a typical receptor to the somatosensory cortex involves three neurons.
- Lateral inhibition improves the two-point discrimination threshold.
Sensory Pathways and Sensations
- The anterolateral system transmits all somatic sensations except vibration sensations.
- The dorsal column-medial lemniscal system transmits all somatic sensations except tickle and itch sensations.
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Description
Explore the complexities of sensory pathways and somatosensory deficits with this quiz. Discover how sensory fibers connect and what happens when spinal cord transections occur. Test your knowledge on the neurological effects of sensory loss and the implications for fine touch, pain, and vibration sense.
