UNIT 5: Ch 14 (Porth's 5th Ed) - Somatosensory Function, Pain, and Temperature Flashcards
While batting, a baseball player is struck in the ribs by a pitch. Place the following
components of the player’s pain pathway in the chronological order as they contribute to
the player’s sensation of pain. Use all the options.
A) Thalamus
B) Dorsal root ganglion body
C) Dorsal root ganglion periphery
D) Axon
E) Cerebral cortex
Ans: C, B, D, A, E
Feedback:
All somatosensory information from the limbs and trunk shares a common class of
sensory neurons called dorsal root ganglion neurons. Somatosensory information from
the face and cranial structures is transmitted by the trigeminal sensory neurons, which
function in the same manner as the dorsal root ganglion neurons. The cell body of the
dorsal root ganglion neuron, its peripheral branch (which innervates a small area of
periphery), and its central axon (which projects to the CNS) communicate with the
thalamus, which in turn communicates with the cerebral cortex using third-order
neurons.
A student is feeling inside her backpack to find her mobile phone. There are a number
of other items in the bag other than the phone. The nurse knows that which of the
following terms best describes one’s ability to sense of shape and size of an object in the
absence of visualization?
A) Stereognosis
B) Astereognosis
C) Modalities
D) Somesthesia
Ans: A
Feedback:
The sense of shape and size of an object in the absence of visualization is known as
stereognosis. Astereognosis is a deficit whereby a person can correctly describe the
object but does not recognize it. “Modalities” is a term used for qualitative, subjective distinctions between sensations such as touch, heat, and pain. Somesthesia describes most of the perceptive aspects of body sensation and requires the function of the parietal association cortex.
A woman with severe visual and auditory deficits is able to identify individuals by
running her fingers lightly over their face. Which of the following sources is most likely
to provide the input that allows for the woman’s unique ability?
A) Pacinian corpuscles
B) Ruffini end organs
C) Meissner corpuscles
D) Free nerve endings
Ans: C
Feedback:
Meissner corpuscles, which are present on the hair-free areas like palms and fingers, are
responsible for fine tactile sensation. Pacinian corpuscles provide input on vibration,
while Ruffini end organs exist in deeper structures that signal continuous states of
deformation. Free nerve endings also detect touch and pressure, but not to the highly
differentiated degree of Meissner corpuscles.
A mother is placing her child into the bathtub. The child immediately jumps out of the
tub and begins to cry, stating his feet are “burning.” The nurse in the emergency
department knows that the child’s response is based on which of the following
pathophysiological principles listed below?
A) Children react much quicker to contact with hot water than adults.
B) The tactile sensation occurs well in advance of the burning sensation. The local
withdrawal reflex reacts first.
C) It takes a long time for thermal signals to be processed before the brain can send a
signal through the spinal cord and tell the foot to withdraw.
D) The thermal processing center is located on the rapid conducting anterolateral
system on the same side of the brain as the injury.
Ans: B
Feedback:
If a person places a foot in a tub of hot water, the tactile sensation occurs well in
advance of the burning sensation. The foot has been removed from the hot water by the
local withdrawal reflex well before the excessive heat is perceived by the forebrain. All other responses are incorrect.
If the patient’s dorsal columns are not functioning, the nurse will observe which of the
following responses during neurotesting, where the nurse asks the patient to close his
eyes and then proceeds to touch corresponding parts of the body on each side
simultaneously with two sharp points?
A) Grimacing when body touched with sharp points
B) No response to two-point discrimination
C) Heightened proprioceptive response
D) Inability to identify which way his finger was moved during the test
Ans: B
Feedback:
When comparing the discriminative dorsal column–medial lemniscus pathway with
anterolateral tactile pathways with testing (with eyes closed), gently brush the skin with
cotton, touch an area with one or two sharp points, touch corresponding parts of the
body on each side simultaneously or in random sequence, and passively bend the
person’s finger one way and then another. If dorsal columns are not functioning, the
tactile threshold two-point discrimination and proprioception are missing, and the
person has difficulty discriminating which side of the body received stimulation.
Match the pain theory to the correct physiologic basis for the pain. A. Specificity theory. B. Pattern theory C. Gate control theory D. Neuromatrix theory
- Light touch applied to the skin would produce the sensation of touch
through low-frequency firing of the receptor. - Repeated sweeping of a soft-bristled brush on the skin over or near a
painful area may result in pain reduction for several minutes. - Proposes that the brain contains a widely distributed neural network
that contains somatosensory, limbic, and thalamocortical components. - Describes how an acute injury is predicted to be but does not take into
account the person’s feelings of how the pain feels to him or her.
Ans: A–4, B–1, C–2, D–3
Feedback:
Specificity theory—describes how an acute injury is predicted to be but does not take
into account the person’s feelings of how the pain feels to him or her; pattern
theory—light touch applied to the skin would produce the sensation of touch through
low-frequency firing of the receptor; gate control theory—repeated sweeping of a
soft-bristled brush on the skin over or near a painful area may result in pain reduction
for several minutes; neuromatrix theory—proposes that the brain contains a widely
distributed neural network that contains somatosensory, limbic, and thalamocortical
components.
Following a knee injury, a football player is taking ibuprofen, a nonsteroidal
anti-inflammatory drug, for the control of pain. Which of the following drug actions is
most likely to result in diminished sensation of pain for the player?
A) The drug inhibits communication by third-order neurons between the thalamus
and cerebral cortex.
B) The drug inhibits the enzyme needed for prostaglandin synthesis.
C) The drug changes the postexcitatory potential in C fibers, leading to pain
sensitization.
D) The drug slows the conduction velocity of myelinated Aδ fibers in the pain
pathway.
Ans: B
Feedback:
Analgesia can be achieved by inhibition of prostaglandin synthesis, as in the case of
many NSAIDs. These drugs do not affect the function of third-order neurons, the action
potential of C fibers, or the conduction velocity of Aδ fibers.
A 60-year-old male client with a long history of back pain has had little success with a
variety of analgesic regimens that his family physician has prescribed. He has recently
been diagnosed with a chronic pain disorder. Which of the following teaching points
about chronic pain would his physician most likely emphasize to the client?
A) “If your pain comes and goes, then we won’t characterize it as chronic, and it will
require different treatment.”
B) “You need to remind yourself that this is a purely physical phenomenon that
requires physical treatment.”
C) “Our challenge is to bring you relief but still treat the underlying back problem
that your body is telling you about.”
D) “These pain signals your body is sending likely serve no real, useful, or protective
function.”
Ans: D
Feedback:
A hallmark of chronic pain is that it usually does not serve any useful function, and that
it is often remote from, or even irrelevant to, the originating cause. Like all pains,
chronic pain is a complex and multifaceted phenomenon that supersedes purely physical
considerations. Chronic pain need not be continuous and unchanging to be characterized
as chronic.
A client in an acute medicine unit of a hospital with a diagnosis of small bowel
obstruction is complaining of intense, diffuse pain in her abdomen. Which of the
following physiological phenomena is most likely contributing to her complaint?
A) Nociceptive afferents are conducting the sensation of pain along the cranial and
spinal nerve pathways of the ANS.
B) First-order neurons are inappropriately signaling pain to the dorsal root ganglion.
C) The client is experiencing neuropathic pain.
D) The client’s C fibers are conducting pain in the absence of damaged Aδ fibers.
Ans: A
Feedback:
Visceral pain, as characterized by the client’s description of her pain, is conducted by
way of nociceptive afferents that use the cranial and spinal nerve pathways of the ANS.
The problem is not likely rooted in the inappropriate firing of first-order neurons or the
substitution of conduction by C fibers. Pain that is attributable to a pathological process
apart from the neural pain network is not normally considered to be neuropathic.
A nurse on a postsurgical unit is providing care for a 76-year-old female client who is 2
days posthemiarthroplasty (hip replacement) and who states that her pain has been out
of control for the last several hours, though she is not exhibiting signs of pain. Which of
the following guidelines should the nurse use for short-term and long-term treatment of
the client’s pain?
A) Reconciling the client’s need for opioid analgesics with the risk of addiction to
these drugs
B) Recognizing the client’s pain is not likely self-limiting
C) Knowing that the client’s self-report of pain is the most reliable indicator of pain
D) Realizing that chronic pain is likely to require innovative and complex treatment
Ans: C
Feedback:
Clinically, the patient’s self-report of pain is the most reliable indicator of pain. The risk
of addiction to opioids is extremely low, and since the client’s pain is acute rather than
chronic, it is likely self-limiting.
A female client with bone metastases secondary to lung cancer is admitted for palliative
radiation treatment and pain control. The client is presently experiencing pain that she
rates at 9 out of 10. Which of the following nonpharmacological treatments is most
likely to be a useful and appropriate supplement to pharmacological analgesia at this
point?
A) Teaching the client guided imagery and meditation
B) Initiating neurostimulation
C) Heat therapy
D) Relaxation and distraction
Ans: D
Feedback:
Given the client’s high pain rating, initiating teaching around imagery and meditation is
unlikely to be effective or appropriate. Neurostimulation requires implantation and/or
placement of internal components, while heat is more likely to address superficial pain
or pain caused by muscle tension. Relaxation and distraction would be plausible
treatment options for this client.
30-year-old female has suffered a third-degree burn to her hand after spilling hot oil
on it in a kitchen accident. Which of the following teaching points by a member of her
care team is most appropriate?
A) “Tell us as soon as you sense the beginnings of a round of pain, and we will start
with analgesics.”
B) “Opioids like often cause constipation, but if this happens to you, we
will discontinue opioids and change to another family of medications.”
C) “Opioids aren’t without side effects, but we will take action to manage these side
effects, so you can continue getting these drugs.”
D) “It’s imperative that we prevent you from developing a tolerance for opioids while
you’re getting treatment for your burn.”
Ans: C
Feedback:
While opioids carry side effects such as constipation, these can be managed in order to continue treatment; constipation would not preclude the continued use of opioids, but
would require management. Pain medications should precede the onset of pain, and
tolerance is not grounds for discontinuing treatment.
Which of the following would be an example of a child born with congenital
insensitivity to pain? A child who
A) develops pins-and-needles sensation after jumping out of a tree.
B) fell off a skate board and fractured ankle but did not feel any pain and just noted
swelling in foot.
C) skinned knee from a bike accident but only told parents when it started burning.
D) cries every time the wind blows because it hurts his face and ears.
Ans: B
Feedback:
Analgesia is the absence of pain on noxious stimulation or the relief of pain without loss
of consciousness. Congenital insensitivity is when the peripheral nerve defect
apparently exists such that the transmission of painful nerve impulses does not result in
perception of pain. Pens-and-needles sensation is called paresthesia. Burning sensations
are usually associated with temperature (hyperthermia). Pain associated with wind (or
any nonnoxious stimuli) is called allodynia.
Which of the following hospital patients is most likely to be diagnosed with complex
regional pain syndrome II (CRPS II)?
A) A man who has been admitted for treatment of continuing hyperalgesia after
sustaining a nerve injury in a motor vehicle accident
B) A woman who requires analgesia more than 3 months after an episode of shingles
C) A male client with diabetes mellitus who requires analgesia prior to each dressing
change on his chronic foot wound.
D) A female who has seemingly unprovoked attacks of pain that are accompanied by
facial tics and spasms
Ans: A
Feedback:
CRPS is marked by the presence of continuing pain, allodynia, or hyperalgesia after a
nerve injury, not necessarily limited to the distribution of the injured nerve with
evidence at some time of edema, changes in skin blood flow, or abnormal sensorimotor
activity in the region of pain. Pain related to shingles is an example of postherpetic
neuralgia, while a need for analgesia prior to dressing changes would not indicate
CRPS. Sudden attacks of pain accompanied by facial tics and spasms may be indicative
of trigeminal neuralgia.
A 58-year-old woman comes to the clinic for evaluation of a sharp, intermittent, severe,
stabbing facial pain that she describes as, “like an electric shock.” The pain occurs only
on one side of her face; it seems to be triggered when she chews, brushes her teeth, or
sometimes when she merely touches her face. There is no numbness associated with the
pain. What is most likely causing her pain?
A) Postherpetic neuralgia
B) Migraine headache
C) Complex regional pain syndrome
D) Trigeminal neuralgia
Ans: D
Feedback:
Her symptoms are characteristic of trigeminal neuralgia, caused by damage to the fifth
cranial nerve, which carries impulses of touch, pain, pressure, and temperature to the
brain from the face and jaw.
