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Question 1
Correct
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A patient presents with loss of pain and temperature sensation in the left leg. He is likely to have a lesion involving:
Your Answer: Right lateral spinothalamic tract
Explanation:The spinothalamic tract is a sensory pathway originating in the spinal cord that transmits information to the thalamus. There are two main parts of the spinothalamic tract: the lateral spinothalamic tract transmits pain and temperature and the anterior spinothalamic tract transmits touch (crude touch). The decussation of this pathway occurs at the level of the spinal cord. Hence, a unilateral lesion of the lateral spinothalamic tract causes contralateral loss of pain and temperature.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 2
Correct
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Production of pain is most likely associated with:
Your Answer: Substance P
Explanation:Substance P is a short-chain polypeptide that functions as a neurotransmitter and as a neuromodulator, and is thus, a neuropeptide. It has been linked with pain regulation, mood disorders, stress, reinforcement, neurogenesis, respiratory rhythm, neurotoxicity, nausea and emesis. It is also a potent vasodilator as it brings about release of nitric oxide from the endothelium. Its release can also cause hypotension.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 3
Correct
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A previously healthy 40-year-old housewife suddenly complains of a headache and loses consciousness. A CT scan reveals subarachnoid haemorrhage. Which of the following is the most probable cause?
Your Answer: Ruptured berry aneurysm
Explanation:Saccular aneurysms, also known as berry aneurysms, appear as a round outpouching and are the most common form of cerebral aneurysm. They are a congenital intracranial defect, and haemorrhage can occur at any age, but is most common between the ages of 40-65 years. A second rupture (rebleeding) sometimes occurs, most often within about 7 days of the first bleed.
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This question is part of the following fields:
- Neurology
- Pathology
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Question 4
Correct
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A lesion involving the suprachiasmatic nucleus of hypothalamus is likely to affect:
Your Answer: Regulation of circadian rhythm
Explanation:The suprachiasmatic nucleus (SCN) in the hypothalamus is responsible for controlling endogenous circadian rhythms and destruction of the SCN leads to a loss of circadian rhythm.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 5
Incorrect
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A 45 year old lady has been diagnosed with Friedreich's ataxia that has affected her medial group of nuclei in the anterior horn of the spinal cord. Which of the following structures will have their muscles affected?
Your Answer: Leg
Correct Answer: Axial muscles
Explanation:The cells in the anterior horn can be arranged in the following three main groups: medial, lateral and central. The medial group of nuclei in the anterior horn of the spinal cord are located along the entire length of the spinal cord and are responsible for the innervation of the axial muscles of the body ( muscles of the head and neck region). Thus this disease will most likely affect the functioning of the muscles of the head and neck.
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This question is part of the following fields:
- Anatomy
- Neurology
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Question 6
Correct
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Which of the following tumours has the best prognosis following surgery?
Your Answer: Schwannoma
Explanation:Schwannomas are histologically benign neoplasms that arise from nerve sheaths, most commonly from sensory nerve roots. They are generally contained within a capsule, and so can be surgically removed without injuring the associated nerve root. They are histologically benign and less than 1% become malignant.
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This question is part of the following fields:
- Neurology
- Pathology
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Question 7
Correct
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Which of the following will show decreased hearing when tested by air conduction but normal hearing when tested by bone conduction?
Your Answer: Fibrosis causing fixation of the ossicles
Explanation:As the cochlea is embedded into bone, the vibrations from the bone are transmitted directly to the fluid in the cochlea. Hence, any damage to the ossicles or tympanic membrane will not show an abnormal result on bone conduction test.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 8
Incorrect
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A sudden loud sound is more likely to result in cochlear damage than a slowly developing loud sound. This is because:
Your Answer: The tympanic membrane becomes flaccid as a sound becomes louder
Correct Answer: There is a latent period before the attenuation reflex can occur
Explanation:On transmission of a loud sound into the central nervous system, an attenuation reflex occurs after a latent period of 40-80 ms. This reflex contracts the two muscles that pull malleus and stapes closer, developing a high degree of rigidity in the entire ossicular chain. This reduces the ossicular conduction of low frequency sounds to the cochlea by 30-40 decibels. In this way, the cochlea is protected from damage due to loud sounds (these are low frequency sounds) when they develop slowly.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 9
Incorrect
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Destruction of the ventromedial nucleus of the hypothalamus will result in:
Your Answer: Loss of appetite
Correct Answer: Loss of satiety
Explanation:The ventromedial nucleus of the hypothalamus is divided into an anterior and a superior part. The anterior part controls the female sexual drive, whereas the superior part is responsible for satiety. Destruction of the superior part of the nucleus will result in overeating, as no signal tells the body that it is satisfied.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 10
Incorrect
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A lesion involving the lateral portion of the dorsal columns at the level of the nape of the neck will most likely affect:
Your Answer:
Correct Answer: Vibratory sensations from the ipsilateral arm
Explanation:At the level mentioned in the question, the lateral portion of dorsal columns comprises of the fasciculus cuneatus. Axons carrying the sensations of touch, vibration and proprioception from the ipsilateral arm enter the spinal cord and ascend in the fasciculus cuneatus, synapsing in the nucleus cuneatus of the caudal medulla. Secondary neurons from this nucleus give rise to internal arcuate fibres, which decussate and ascend to the thalamus as the medial lemniscus. Tertiary neurons from there project to the ipsilateral somatosensory cortex. Thus, any damage to the fasciculus cuneatus will result in a deficit in tactile, proprioceptive and vibratory sensations in the ipsilateral arm, and not the contralateral arm.
Fine motor control of the fingers is mainly carried by the ipsilateral lateral corticospinal tract in the lateral funiculus of the cord. Motor control of the contralateral foot is carried by the ipsilateral corticospinal tract in the lateral funiculus of the cord. Lack of sweating of the face could be produced by interruption of sympathetic innervation. Proprioception from the ipsilateral leg is carried by the fasciculus gracilis in the medial part of the dorsal columns.
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This question is part of the following fields:
- Neurology
- Physiology
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