Localizing the Intraparietal Lobule Part 2
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I want to give you another tool to localize
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the intraparietal sulcus.
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First, I'd like to draw it in the sagittal projection.
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And then I'll show you this sign that you can use.
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So, here it is as an arcuate shaped structure.
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Remember, you don't see the whole thing
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because it's so convoluted
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and involuted from the surface of the brain.
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It's very deep.
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But if I were to show you exactly where
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that spot was by cross-referencing it,
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it corresponds right to this locus right here.
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Now, we see part of it on this one cut.
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And if I was to take the brain, as we did before,
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and divide it up into 12 o'clock and 6 o'clock,
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then we have at the widest biparietal diameter,
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we've got 9 o'clock and 3 o'clock,
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something like that.
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And then we're going to take this sulcus,
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which goes from 3 o'clock,
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and it usually lands somewhere around here
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at around 5 o'clock.
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And then on the other side,
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this would be 7 o'clock.
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We can actually see it here at 7 o'clock.
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Now, 75% of the time on the left side,
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this intraparietal arcuate-shaped sulcus is continuous.
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In this case, it's a little bit broken in the back.
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On the right side, it's a little more disorganized,
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so it's hard to pick it out from the
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9 o'clock to the 6 o'clock position.
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So, it's a little easier on the left and then you
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extrapolate on the right just to make it work,
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So if I take these lines away, you can see it now.
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There it is right there,
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going from 3 o'clock to approximately 5 o'clock,
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maybe a little bit past 5 o'clock,
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in the posterior aspect of the left parietal region
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of the brain. The intraparietal sulcus,
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the clock face sign for identifying it as the divider
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of the superior and inferior parietal lobule.
Stephen J Pomeranz, MD
Chief Medical Officer, ProScan Imaging. Founder, MRI Online
ProScan Imaging
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