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NBME 20 Answers

nbme20/Block 4/Question#5
Immediately after a cerebral infarction, a ...
Area labeled ‘A’ (Broca’s area)🔍

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https://imgur.com/a/lCFnj1e FA19 P489 Cerebral cortex regions

Could anyone help me on why this couldn't be C (facial portion of the homonculus in the primary motor cortex)? It explicitly mentions motor issues with the face - not just speech. I understand why it would be Broca's - that's what I put originally. But the last sentence mentioning motor disruption caused me to change my answer. Thanks.

jaeyphf  I didn't even think about the motor part during the question, but it might be related to the homonculus (FA 2020 pg 502). Motor and sensory areas of the lower face generally fall towards the lower half of the brain. Answers B/C/D would probably show some hand or arm involvement. +1  

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submitted by xxabi(195),

Broca’s aphasia: expressive (motor aphasia) with agrammatism (pts aware that they don’t make sense) - area A Wernicke’s aphasia: receptive (sensory) aphasia with impaired comprehension (pts lack insight)

breis  Why would B be incorrect? I realize Broca is "technically lower" but A seems too low to be causing weakness of the lower 2/3 of the face? Am I missing something? +  
shaeking  @breis B is incorrect because of the lower 2/3 of the face weakness. B isn't located on the motor cortex but in the premotor cortex, plus it isn't low enough for the lower two thirds of the face. https://thebrain.mcgill.ca/flash/a/a_06/a_06_cr/a_06_cr_mou/a_06_cr_mou.html https://www.sciencenews.org/blog/science-ticker/homunculus-reimagined +1  
cienfuegos  @breis, per UW: "a/w r. hemiparesis (face & UE) bc close to primary motor cortex" +  
almondbreeze  B is close to premotor cortex which is involved in learned or patterned skills & in planning movements. (i.e. two-hand coordination) slide 25/37 :https://www.slideserve.com/hal/the-motor-system-and-its-disorders +  
almondbreeze  B is also close to frontal eye field; eyes look toward the lesion FA pg. 499 +  
frijoles  I incorrectly picked C. When answering this, Broca's "broken speech" was my first thought, but I figured a lesion causing a facial droop would have to involve the motor strip so I prioritized that and chalked up the speech issue to dysarthria (I understand this is more of a "slurred speech" than broken, abrupt speech, but again, I simply misprioritized concepts.). So for the record, Broca area is part of the motor cortex? +  

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