NBME12 spoiler - neuro question

[Phloston]

---

Members do not see this ad.

I'm not allowed to post the actual question based on copyright issues, but there's a question with a spinal cord cross-section. They mention that this guy has weakness and atrophy of the intrinsic muscles of the left hand, then they ask you to identify the lesion in the spinal cord.

I knew it was LMN, so that must have been ipsilateral anterior horn, so I selected F, but it was wrong on extended feedback.

On one of the forums somewhere somebody mentions that what looks like the adjacent lateral column is actually the lateral aspect of the anterior horn, and that there's a medial AND lateral component and that this factors in. Apparently F is the medial component and D is the lateral component.

Does anyone know about this concept, or better yet, this question?

 

[ijn]

You can see the actual individual horn cells in G. Notice how they're a different color than the rest of the ventral horn. You can't see any distinct cell bodies in F.

This is a cervical spinal cord section. This isn't a pathology board exam so they probably don't expect you to diagnose based on the picture, but they tell you this is related to a hand problem. You aren't going to see the lateral horn cell bodies until you get to T1.

 

[Phloston]

Thanks, ijn. I didn't even notice that the lateral aspect was darker, quite frankly. Tough question. Thanks.

 

[VisionaryTics]

Thanks, ijn. I didn't even notice that the lateral aspect was darker, quite frankly. Tough question. Thanks.

For anterior horn, cells of more proximal muscle fibers are medial, more distal muscle fibers (hand) are lateral.

 

[thecalccobra]

What a trick question. What's F pointing to exactly?

 

[ijn]

Rexed lamina VIII... mostly motor interneurons