Question
Identify the type of the fibre marked in the image of internal capsule:
| A. |
Projection fibres
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| B. |
Short association fibres
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| C. |
Long association fibres
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| D. |
Commissural fibres
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Show Answer
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Correct Answer � A
Explanation
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Answer A. Projection fibres
Internal capsule
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Area of white matter in the brain that separates the caudate nucleus and the thalamus from the putamen and the globus pallidus.
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The internal capsule contains both ascending and descending axons.
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It consists of axonal fibres that run between the cerebral cortex and the pyramids of the medulla.
Components
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The internal capsule is V-shaped when cut transversely (horizontally).
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When cut horizontally:
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the bend in the V is called the genu
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Anterior limb of the internal capsule.
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the posterior limb or crus posterius is the part behind the genu, between the thalamus and lenticular nucleus.
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the retrolenticular portion is caudal to the lenticular nucleus and carries optic tracts including the geniculocalcarine radiations.
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the sublenticular portion is beneath the lenticular nucleus and are tracts involved in the auditory pathway from medial geniculate nucleus to the primary auditory cortex (Brodmann Area 41).
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Gross motor strength is impaired with ischemia of the internal capsule.
