new_n_lost
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An elderly nursing home patient has had multiple small strokes. On several occasions she has aspirated food, and neurological examination reveals that her gag reflex is absent. These findings
suggest involvement of the nucleus of which of the following cranial nerves?
A. Facial (VII)
B. Glossopharyngeal (IX)
C. Hypoglossal (XII)
D. Spinal accessory (XI)
E. Vestibulocochlear (VIII)
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| icandoittoo
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B
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| hope4dabest
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B
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| SmokyWaters
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| new_n_lost
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icandoittoo wrote:
B
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| new_n_lost
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The correct answer is B.
Cranial nerve IX is the glossopharyngeal nerve, which has a nucleus in the medulla and is necessary for the gag reflex. The gag reflex is elicited by touching either side of the posterior pharynx with a tongue blade, producing bilateral elevation of the palate and bilateral contraction of the pharyngeal muscles. The afferent of this reflex arc consists of the ipsilateral glossopharyngeal nerve, while the vagus nerve, bilaterally, supplies the efferent limb.
While the glossopharyngeal nerve may seem to be one of the less important cranial nerves, you should remember to test for its function, as a loss of gag reflex can lead to the patient's death secondary to an aspiration pneumonia. This form of pneumonia can be difficult to treat, as it commonly is due to a mixed flora, which may include a variety of anaerobes.
Cranial nerve VII (choice A) is the facial nerve, which supplies motor function to the face, but does not supply the oropharynx.
Cranial nerve XII (choice C) is the hypoglossal nerve, which supplies the tongue. It is not involved in the gag reflex.
Cranial nerve XI (choice D) is the spinal accessory nerve, which supplies the trapezius and sternocleidomastoid.
Cranial nerve VIII (choice E) is the vestibulocochlear nerve, responsible for hearing and equilibrium.
___________________
FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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