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NBME Answers

free120/Block 3/Question#9

A 72-year-old woman is brought to the emergency ...

Area labeled 'C'

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submitted by benwhite_dotcom(46),

Stroke characterized by left hemiparesis and right CN12 palsy. Crossed findings mean a brainstem lesion. Right (ipsilateral) tongue, left-sided (contralateral) weakness means the exiting right hypoglossal nerve has been affected (within the right medulla). C is the pyramid where the corticospinal tract runs to control muscles (prior to the decussation). This is known as the medial medullary syndrome or Dejerine syndrome.

d_holles  It seems to me that the brain stem problems can all be answered using the Rule of 4s rather than memorizing the actual brain stem histology. +1  

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submitted by canyon_run(0),

I can’t seem to find a similar image online that describes exactly what the other areas are covering. Any help?

benwhite_dotcom  See this image (Fig.6) from https://teachmeanatomy.info/neuro/brainstem/medulla-oblongata/ A and D, for example, would reflect lesions that cause what is called lateral medullary syndrome (Wallenberg syndrome). +  
canyon_run  Thank you! Would E then be the inferior vestibular nucleus based on that linked image? Also, is hypoglossal involved in the stem because of damage to the nerve fibers themselves rather than the nucleus? +  
benwhite_dotcom  I think the level in the teachmeanatomy link is a bit off from the NBME image. I assume the NBME is showing E as the hypoglossal nucleus (https://en.wikipedia.org/wiki/Hypoglossal_nucleus). Yes, it’s the fibers. The nucleus is ventral. +