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Question 1
Incorrect
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Oculomotor (CN III) palsy with sparing of the pupillary reflex is most likely caused by which of the following:
Your Answer: Brainstem metastases
Correct Answer: Diabetes mellitus
Explanation:Compressive causes of CN III palsy cause early pupillary dilatation because the parasympathetic fibres run peripherally in the nerve and are easily compressed. In diabetes mellitus the lesions are ischaemic rather than compressive and therefore typically affect the central fibres resulting in pupillary sparing.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 2
Incorrect
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A 53-year-old man arrives at the emergency department complaining of visual impairment in his right eye. On examination, you notice that neither his right nor left pupil constricts when you shine a light in his right eye. When you flash a light in his left eye, the pupils of both his left and right eyes constrict. Which of the following nerves is the most likely to be affected:
Your Answer: Oculomotor nerve
Correct Answer: Optic nerve
Explanation:In full optic nerve palsy, the afferent pupillary light reflex is lost. Because the afferent optic nerve does not sense light flashed in the afflicted eye, the ipsilateral direct and contralateral consensual reflexes are gone. However, the contralateral direct and ipsilateral consensual reflexes are intact because the efferent oculomotor nerve is normal.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 3
Incorrect
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A 62 year old man has sustained a penetrating injury to the submandibular triangle. On examination, his tongue is weak and when protruded deviates to the left. Which of the following nerves has most likely been injured:
Your Answer: Right hypoglossal nerve
Correct Answer: Left hypoglossal nerve
Explanation:Damage to the hypoglossal nerve results in weakness of the tongue, with deviation of the tongue towards the weak side on protrusion.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 4
Incorrect
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Regarding the accessory nerve, which of the following statements is INCORRECT:
Your Answer: The accessory nerve innervates the sternocleidomastoid and the trapezius muscle.
Correct Answer: Accessory nerve palsy results in the inability to nod the head.
Explanation:Accessory nerve palsy results in inability to shrug the shoulders and to rotate the head to look at the opposite side to the lesion.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 5
Correct
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A tumour compresses the jugular foramen of a 50-year-old patient. Compression of several nerves in the jugular foramen will result in which of the following complications?
Your Answer: Loss of gag reflex
Explanation:The glossopharyngeal nerve, which is responsible for the afferent pathway of the gag reflex, the vagus nerve, which is responsible for the efferent pathway of the gag reflex, and the spinal accessory nerve all exit the skull through the jugular foramen. These nerves are most frequently affected if the jugular foramen is compressed. As a result, the patient’s gag reflex is impaired. The vestibulocochlear nerve is primarily responsible for hearing. The trigeminal nerve provides sensation in the face. The facial nerve innervates the muscles of face expression (including those responsible for closing the eye). Tongue motions are controlled mostly by the hypoglossal nerve.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 6
Correct
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A patient with diplopia is found to have eye deviation downwards and outwards. The likely nerves that are affected are:
Your Answer: Oculomotor nerve
Explanation:The results of an oculomotor (CN III) nerve palsy are a depressed and abducted (down and out) eye, ptosis, diplopia, and a fixed and dilated pupil.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 7
Correct
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Which of the following clinical features is NOT typical of a facial nerve palsy:
Your Answer: Inability to raise the eyelid
Explanation:Facial nerve palsy can result in inability to close the eye due to paralysis of the orbicularis oculi muscle. Elevation of the eyelid in eye opening is a function of the levator palpebrae superioris muscle and the superior tarsal muscle, innervated by the oculomotor nerve and the sympathetic chain respectively.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 8
Correct
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Which of the following is NOT a typical feature of an abducens nerve palsy:
Your Answer: Inability to look up
Explanation:CN VI palsies result in a convergent squint at rest (eye turned inwards) with inability to abduct the eye because of unopposed action of the rectus medialis. The patient complains of horizontal diplopia when looking towards the affected side. With complete paralysis, the eye cannot abduct past the midline.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 9
Incorrect
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In the emergency department, a 50-year-old female appears with a lack of sensation over the front two-thirds of her tongue. Taste and salivation are both present. The patient might have damage which of her nerves?
Your Answer: Hypoglossal nerve
Correct Answer: Lingual nerve
Explanation:The lingual nerve, a branch of the mandibular nerve, transmits sensation to the anterior two-thirds of the tongue. The chorda tympani, a branch of the facial nerve, transmits taste to the front two-thirds of the tongue as well as secretomotor innervation to the submandibular and sublingual glands. As a result, any damage to the lingual nerve can cause changes in salivary secretion on the affected side, as well as a loss of taste in the anterior two-thirds of the tongue and temporary or permanent sensory changes in the anterior two-thirds of the tongue and the floor of the mouth.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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Question 10
Incorrect
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A 35-year-old lady has suffered a serious brain injury. Her uvula has deviated to the right, according to inspection. Which of the following nerves is likely to be affected?
Your Answer: Right glossopharyngeal nerve
Correct Answer: Left vagus nerve
Explanation:When the vagus nerve is damaged, the soft palate is paralyzed and the uvula is shifted away from the affected side. The vagus nerve innervates the uvulae muscle, which forms the uvula’s core. If only one side is innervated, contraction of the active muscle will draw the uvula towards it.
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This question is part of the following fields:
- Anatomy
- Cranial Nerve Lesions
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