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NBME 21 Answers

nbme21/Block 1/Question#50

A photograph is shown of a myelin-stained cross ...

Loss of sensation to vibration over both feet

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 +2  upvote downvote
submitted by haliburton(74),

this is a cervical spinal cord section. the cuneate fasciculus is intact (UE) vibration and proprioception, but the white section is the gracile fasciculus (LE) and is damaged. I think the lateral portion that is uneven is just natural/artifact.

arezpr  thorax section +3  
guillo12  How do you know the gracile fasciculus is damage?!?! +1  
cr  which parte of the image its damage?, the pink? or black? +  
usmile1  the pink park yes +1  
d_holles  If you look at https://en.wikipedia.org/wiki/Gracile_fasciculus#/media/File:Spinal_cord_tracts_-_English.svg you can see that the closer to the center = legs, while further away = arms. +1  
hyperfukus  i still don't see where the damage is lol! FML +  
hyperfukus  i finally figured it out lol that was a slow moment i hope im not this slow on step yikes! +  
angelaq11  @hyperfukus I had the same problem at first, marked it and then came back. If you remember, in the spinal cord the white matter and gray matter are "reversed" compared to the brain. That said, if the butterfly shaped region (ie, the gray matter) is colored (in this case) lilac and the rest (ie, white matter) is blackish, the only thing that is actually abnormal, is the region where the dorsal columns are, because it stains just like the normal gray matter. After that, you have to think about which fasciculus is damaged, the gracilis or the cuneatus. The gracilis is medial while the cuneatus is lateral (picture someone with glued legs and open arms). Hope this helped +  




 +0  upvote downvote
submitted by ragacha(1),

PAGE 492 FA 2018 DAMAGE IN DORSAL COLUMN (funtion are: pressure, vibration, fine touch, proprioception) SYNAPSE 1 : N. graciLe ( Lower body, Legs) AND N. cUneatus (Upper body, arms)

nor16  Cuneatus = Cervical, write into columns CG ( fron left to right) Cuneatus, Gracilis (CG) +